This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------ Lots of user tips to reduce Sherline backlash. Primarily backlash on the mill is discussed, but there is also discussion about this issue for the lathe and also the rotary table and for Taig machines. Solving backlash problems on a Sherline mill or lathe is a common question and users have offered some very thoughtful methods of dealing with it. The majority of backlash questions deal with the mill, probably because the mill has more axes to give a problem. The Sherline lathe (as any lathe) will show measurable backlash, and many solutions or tips provided here for the mill can be directly used or adapted for the lathe. I have added some lathe backlash discussions for the simple reason that solutions there can help some mill problems. Simplistically, here we will define "backlash" as the element of "slop" in the screw mechanisms that move the milling machine table or head. When you crank in one direction, and then reverse direction, there will be a short interval while the handle turns (and the handle's scale reading changes) but the table or head does not yet move. If not corrected for, a cutting position error will result. Backlash is present on every make and model of metal lathe or milling machine or metal shaper; some have more, some have very little. The methods used for the Sherline may give you ideas that can be adapted to Taig lathes and mills and your own situation. If you got to this file directly from my HOME PAGE, return there by using your browser's back button. BUT if you came to this file as the result of a web search engine, see many additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/index.html SAFETY WARNING BEWARE: DO NOT ASSUME that any subject matter or procedure or process is safe or correct or appropriate just because it was mentioned in a news/user group or was included in these files or on this site or on any other web site or was published in a magazine or book or video. Working with metals and machinery and chemicals and electrical equipment is inherently dangerous. Wear safety devices and clothing as appropriate. Remove watches, rings, and jewellery -- and secure or remove loose clothing -- before operating any machine. Read, understand and follow the latest operating procedures and safety instructions provided by the manufacturer of your machine or tool or product. 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(c) Copyright 2003 - 2015 Machining and Metalworking at Home The form of the collected work in this text file (including editing, additions, and notes) is copyrighted and this file is not to be reproduced by any means, including electronic, without written permission except for strictly personal use. ========================================================================== From: "Carol & Jerry Jankura" Subject: Y Slop [sherline] Folks: I've got a model 2000 mill that started out as a manual machine which was then converted to CNC using Sherline's coupler kit and motors. Everything's working well, but I've noticed that I get excessive backlash on Y. (You can move the carriage quite a bit, we're not talking thousandths here.) I can tighten the small nut to eliminate it, but after a while, it comes back. I'm thinking of using something like Locktite, but first thought that I'd ask here to see if there's anything else I should be doing. Carol & Jerry Jankura Strongsville, Ohio ------- Date: Fri, 21 Jun 2002 08:35:42 -0700 From: "Craig Libuse" Subject: Re: Saddle nut > Thanks for the comments, as always, Sherline has excellent support! I > did learn why I couldn't get my old backlash nut an pointer to work. I > had thought I'd removed the slack, but hadn't, so the leadscrew just > backed out of the nut. I'm not sure "what's in the table", but just > running the stepper to "take up the slack" wasn't doing it for me. I'd > almost think there was a sliding nut inside there! Oh well, all's > well now. Alan: Inside the mill saddle is a brass "nut" which is actually round with an internal thread. It is held in place inside the saddle with a set screw. This is the nut against which the antibacklash nut on the outside is tightened to pull backlash out of the leadscrew threads. You can see these nuts in the exploded view as P/N 50200 (X) and 40890 (Y). Makes sure these nuts are held securely with the set screws so they can't move inside the saddle. If you adjust the backlash too tight, the threads on both the nut and the antibacklash nut, which is also brass, wear faster. Eventually they will have to be replaced. CNC use also puts more wear on these components, because the process makes it easier to run the table back and forth more often and at higher speeds than would be possible by hand cranking. You can expect to replace these nuts eventually if you use your machine a lot, especially keep your backlash adjusted fairly tight (.003 or less). By design, the cheapest parts get the wear rather than the steel leadscrew. New X and Y nuts are only $2.00 each. Craig Libuse Sherline Products Inc. ------- Date: Mon, 24 Jun 2002 08:54:06 -0700 From: "Craig Libuse" Subject: Re: HELP!!!! [sherline] June 21, 2002 "santorelli333" wrote: >> I have a(2) problem, the feed on my 5410´s y axis is loose(there is play in the point where the feed-screw is attached to the black disk that holds it(behinde the feed handle)) the result is chatter and poor finish + movement where it apears thet the endmill tries to grab the work-piece and pull it along but the movement is only as big as the give in the feed screw attachement. my second prob is tht the brass bushing that the srew goes throug is worn in its treads(the outer ones that attches the bushing to the mill table, resulting in the backlash adjustment beeing effectively lost) as far as to which threads are worn out the ones in the aluminum (mill-table) seems to be the most likely since brass is stronger than alu... At this point I am thinking "why oh why didn´t I buy a taig-mill" any suggestions to what I can do to the mill to restore it and rid me of such thoughts is desperately sought.....San PS: to pre-empt suggestions about having mistreated the mill....I have seen many an example of sherlines that have the anodizing on the ways almost completely worn off(the anodizing on my ways are 100% and like new) due to religious cleaning and lubrication....and cuts are kept to max 1 mm in alu and 0.2 in iron (using a 10mm carbide end-mill). << Dear San: It sounds like you need a new y-axis nut and antibacklash lock. Fortunately, they are inexpensive and easy to replace. Order P/N 51200 (metric y-axis nut) for $2.00. If you have the older "pointer" style lock, order antibacklash nut P/N 51120 ($.2.00). If you have the newer "star gear" style lock, the part number is 51140. Follow the instructions on page 11 of the instruction manual to remove the backlash. Make sure you pull the saddle fully toward you to take out all space between the handwheel and the thrust before you tighten the handwheel set screw. Try this first before you replace the nuts. By the way, the X-axis nut is held inside the saddle with a set screw. You will have to remove the table to get to it. See the exploded view to understand how it is held in place. Craig Libuse Sherline Prouducts Inc. ------- Date: Tue, 30 Jul 2002 15:05:50 -0700 From: Randy Gordon-Gilmore Subject: Fun with Moglice [A FOLLOW UP TO A RECENT DISCUSSION IN THE SHERLINE GROUP AS TO ELIMINATING LEADSCREW BACKLASH] This weekend I cast Moglice nuts on my Sherline mill leadscrews and my Sherline lathe cross slide screw (due to the way I cast the nuts, I couldn't do the lathe saddle nut at the same time, unfortunately...) I'm extremely happy with the results. The Sherline mill column has a brass nut which kind of floats relative to the head. (The lathe saddle is the same.) The nut is held by a single 10-32 screw, and perched on the points of two setscrews that determine its alignment relative to the head. For the Moglice retrofit, I was not satisfied with this arrangement. Since the Moglice will have next to zero clearance, I wanted a solidly- and repeatably-mounted nut. I measured the distance between the nut mounting surfaces (lateral and fore-and-aft) and the leadscrew centerline. Then I silver-soldered brass shim on both mounting surfaces to bring the nut center in line with the leadscrew center, when it was bolted up tight to the head. I drilled out the nut to leave 1/16" wall, and roughened up the I.D. with a small slotting cutter in my Dremel tool. I turned up centering rings from some Teflon rod to hold the leadscrew tightly and accurately centered in the bore in the column (and thus parallel to the head travel) while I cast the Moglice. For the mill and lathe saddles, I milled out pockets for the Moglice. I used Ron Ginger's idea of using the original brass nuts and "anti-backlash" nuts to contain the Moglice from running out the ends of the bore. The leadscrews run in a clearance hole in the saddle, which is step-drilled to accept the nut, which is just a little cylinder of brass tapped for the leadscrew. I extended the enlarged bore to place the brass nut past the milled-out bore, and filed the flanges off the "anti-backlash" nuts to give the second containment nut. On the lathe, I used a 1/4-20 brass thread insert and turned it to the right O.D. Since the Moglice is described as "fluid", I was imagining how it would flow out any little gap, but was unsatisfied with the idea of using putty in the threads to seal. (By the way, I made the mill saddle recess a little too big, and broke through into the V-way area behind where the gib sits-I did plug that with plumber's putty.) After much thinking during my commute drive, I hit on the idea of using Teflon pipe tape to wind on the threads behind the containment nuts. That worked very well, and no Moglice leaked out at all. The Moglice release spray is wax dissolved in naptha and some other solvents. After degreasing the leadscrews with lacquer thinner and pre-placing the backup nuts, I sprayed two good coats (5-6 seconds per leadscrew) of the wax and let the screws sit overnight. The spray goes on translucent, but dries to a white waxy appearance. I assembled the leadscrews in the saddle bores, and placed the mill head and leadscrew in place on the column. I wound Teflon tape on the column leadscrew in place, and lowered the bored-out nut onto the mass of Teflon. This was enough to seal it. I did all this prep work on Saturday. On Sunday afternoon, I cast the Moglice. The filled component of the Moglice was the consistency of un-homgenized peanut butter-all the solids had settled to the bottom. I pre-mixed it with a Popsicle/craft stick, scraping the sides and bottom of the container well. I then discarded the stick, added the other component and mixed well with a second stick. This way, there would be less of a chance for unmixed resin. The mixed Moglice was about the consistency of honey. I filled the recesses in the mill and lathe saddles and then turned to the column nut. The clearance was so small that I could only apply a fraction of a cubic centimeter (using a small disposable plastic syringe) at a time, and then vibrated it down into the gap by pressing the platen of a palm sander (with the sandpaper removed!) against the nut. I repeated this 4 or 5 times, until the nut seemed full. I went back and vibrated the saddles too. Monday night when I returned from work, I freed the leadscrews. I had read of the difficulties of breaking the leadscrews free initially, and was prepared to use a lot of force. I wrapped layers of brass shim around the leadscrew, and gripped it with a Vise-Grip. To my surprise, the leadscrew broke free easily with relatively little torque (probably not enough to twist the head off a 4-40 screw.) and, after I removed the Teflon tape, the leadscrews all turned freely by hand. I probably was more generous with the release spray than others have been, but I can't feel any play at all by hand. I'm really anticipating reassembling the mill, tramming it in, and measuring the backlash directly. But I have a feeling that it will be well small enough in any case! :-) For the lathe, I could not cast the saddle nut at the same time, because it needs to be solidly bolted to the saddle, and the whole assembly tipped up on end. This conflicted with casting the cross slide nut, so I'll need to buy a second batch of Moglice to do the one nut (well less than a cubic centimeter.) In all, I used possibly a third of the Moglice. The rest, unfortunately, is a hardened mass in the container. If anyone in the area is planning to Moglice anything, let me know and we can share the next batch (as well as the spray release, of which I used a miniscule amount!) The Moglice I used is the 1000 Fluid, which contains Teflon. I'm really looking forward to using the "near-zero-backlash" Sherlines! Photos with captions are in a folder named "Fun with Moglice" in the photos area of the cad_cam_edm_dro Yahoo group. Best regards, Randy ------- Date: Tue, 30 Jul 2002 15:31:27 -0700 From: Alan Marconett KM6VV Subject: Re: Fun with Moglice Hi Randy, Nice work! Don't know if I'm ready to modify my old mill yet, 'tho. I see TWO threaded brass "nuts" per X and Y leadscrew, is that true? I only found one (it came out in the middle of cutting a part, ouch!) on my X axis (17 year old Sears/Sherline mill). The Y hasn't come out by it's self, ...yet. There is ONE setscrew for each (X and Y) axis. The brass "nut" being loose was probably the reason I couldn't keep the star washer "engaged" a few months ago (before U.K. and Squaw Valley trips). Best regards, Alan KM6VV ------- Date: Wed, 31 Jul 2002 13:42:29 -0400 From: "Ron Ginger" Subject: RE: Moglice I did my Sherline with a similar product from Philadelphia Resins. I believe it could be done with any good epoxy resin and either graphite powder or moly power mixed in. The directions say to mix the entire batch at once, but I have used lots of epoxy in boatbuilding, so I carefully measured out the two parts and mixed a small batch. That worked fine for me. My moglice nuts have been on a Sherline for a couple years and they still work fine. ron ginger ------- Date: Wed, 31 Jul 2002 15:43:13 -0400 From: "Van Lupo" Subject: RE: Moglice [WHERE TO BUY?] Well one place is: http://www.moglice.com/ Van ------- Date: Fri, 02 Aug 2002 12:49:27 -0700 From: Randy Gordon-Gilmore Subject: Re: Fun with Moglice At 03:31 PM 7/30/2002 -0700, Alan wrote: >see TWO threaded brass "nuts" per X and Y leadscrew, is that true? The second nut on each axis is the "anti-backlash" nut with the star-shaped flange removed (filed off by hand.) >it's self, ...yet. There is ONE setscrew for each (X and Y) axis. Yes, the recess I machined goes right through the Y setscrew, and the X setscrew is the one on the bottom that I plugged with the cut-down nylon capscrew. >The brass "nut" being loose was probably the reason I couldn't keep the >star washer "engaged" a few months ago (before U.K. and Squaw Valley My nuts kept coming loose too (actually, I'm more often described as having a screw loose!) but were the older style with just a little "pointer" to retain them, instead of the current retainer that is a lot like the safety retainer I've seen for use on externally-wrenching cap screws. Best regards, Randy ------- Date: Fri, 02 Aug 2002 15:02:17 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash, was Fun with Moglice Hi Randy: My "star washer" is on a very short threaded rod. I didn't even recognize yours, which looks like it's as long as the one secured in the middle of the leadscrew hole by the setscrew. The old mill star washer uses a "pointer" to engage it, and is less secure then the newer system that is similar to a pair of small gears (star gears?) that engage. The additional one is secured with a nice allen head cap screw (from descriptions I've studied). I've got a new Deluxe 5400 mill ordered, with a bigger y axis, spindle riser block and the improved anti-backlash hardware. I'm anxious to get it running CNC. Then I'll retire my old mill to manual work, or possibly sell it (list, or ebay). I'm of the opinion that the additional throat will enable me to get the rotary table in the proper position to allow me to cut timing belt pulleys (I've written a program to calculate them), and allow a little bigger work to be handled. Best regards, Alan KM6VV P.S. The mill paid off, I was able to cut some custom aluminum plates for modules we manufacture for our "hand held automotive test computer", which makes me more useful ($$) to the company! ------- Date: Sat, 03 Aug 2002 16:37:44 -0700 From: Randy Gordon-Gilmore Subject: Re: Sherline Mill backlash and Fun with Moglice At 03:02 PM 8/2/02 -0700, Alan Marconett KM6VV wrote: >uses a "pointer" to engage it, and is less secure then the newer system >that is similar to a pair of small gears (star gears?) that engage. The Yes, that's it. My memory was wrong about the new system (and after I mistakenly ordered a pair of the new locks a while back!) I have the mill mostly reassembled. An interesting thing happened--the Z-axis Moglice nut, which has never been off the leadscrew, is very free. The X and Y nuts, which have been sitting off the screws, were tighter when I put the screws back in--not more than hand tight, but a significant drag. The Moglice seems to have maybe a little long-term shrinkage as it continued to cure--I only left it to cure a day before disassembling from the leadscrews. I also had forgotten what a pain it is to reassemble and adjust the gibs, to get the axes shake-free but not binding. By tonight I'll have the stepper motors back on and do some trial back-and-forth jogging with CNC Pro. My workbench situation has been complicated :-) by the fact that I just inherited a Techno-Isel gantry table. X-Y-Z movement is about 20x20x4 inches, with about 4 inches clearance under the gantry. It is an older model (what they call Gantry I) with exposed linear shafting, but it does have ballscrews and is fitted with fabric bellows way covers. The leadscrews are metric, so there are 1270 steps per inch (I don't know yet whether the controller is in full or half step mode though.) It's all made from aluminum extrusions screwed together, and should be a great complement to the Sherline. I will buy a Sherline headstock/motor assembly when I have the extra cash. >P.S. The mill paid off, I was able to cut some custom aluminum plates >for modules we manufacture for our "hand held automotive test computer", >which makes me more useful ($$) to the company! That's great, Alan! So far my equipment has not started to "earn its keep" but I hope that day is not too far off... Best regards, Randy -------- Date: Sun, 04 Aug 2002 14:25:12 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Randy, I'm once again having problems with the 'Z' axis. In working on a casting this weekend, a 1/4" endmill in an endmill holder dug in, continued to cut deeper and deeper until it ruined it. I had it happen more then once, before figuring out that saddle nut was shifting. I've always had a little problem with the 'Z' axis, it never really seems to allow close adjustment when at the bottom of the travel. Sure, I tightened it up again, but I'd really like to better understand it's proper adjustment. When my new mill gets here, I intend to study it, and hopefully a NEW machine in proper adjustment will suggest what's wrong with my 17+ year old Sears/Sherline. I do have a new saddle nut for it, although I'm not so sure that it's something like the leadscrew being out of alignment with the 'Z' ways. I'm hoping the "manual" for the 5400 will give some hints. I have no idea where my old manual might be, or if the Sears version even had the information. There is some on the Sherline website. I am envious! The Techno-Isel gantry table sounds like a great project! I still have the ways and hardware for a 12" x 12" x 3" PCB router table, but I never seen to get back to it. My youngest son was eyeing it, I think he has some more wood projects in mind. SO, I'd better get back to it! Best regards, Alan KM6VV -------- Date: Mon, 5 Aug 2002 06:14:35 -0500 From: "Nance, Tom" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice Alan, I've had that same problem. I'd be cutting along just fine when all of a sudden the z-axis would drop about a 1/32 to 1/16th of an inch. It's a real treat when I'm using a fly cutter! You would think with the weight of the motor and head assembly there would be no way that the thing could fall; it would always be at the "bottom" of the leadscrew thread. I can't tell you how many things I have ruined. Whenever I position the z-axis, I place my hand behind the pulley and haul down on the z-axis to make sure it is "bottomed out". That can't be what the designers had in mind so there's something amiss. I'd sure like to know what is happening. Tom -------- Date: Mon, 05 Aug 2002 12:55:43 -0000 From: "kevin_sedota" Subject: Re: Sherline Mill backlash and Fun with Moglice I have the same basic problem. I've fiddled with it a bit but have never found anything loose or anything that I could explain it. I have about .011 play in my Z axis from where I set the reading to where the tool will pull down to. I just include this measurement in anything I cut where the exact depth is important. ------- Date: Mon, 5 Aug 2002 09:05:42 -0400 From: "Carol & Jerry Jankura" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice Hi, Alan, Randy, Tom: When I bought my model 2000 mill, I found a similar problem, although not to the extent of 0.030 -> 0.060. One problem that I found was that the link between the saddle nut and the saddle of the Z axis actually moved left->right a little bit before the saddle moved up or down. It turns out that, I believe, the gib on the Z-Axis was too tight. I found this out when, after damaging the original gib by running the "free" end into a piece being milled, I had to replace and readjust it. After that adjustment, things worked a lot better. Also, if you're working with a manual mill, I'd suggest that you make sure that axis lock is engaged before making any final cuts. (I know it's tempting not to engage it for many of the roughing cuts, and that's ok as long as the "slop" does not move you past the "finish" surface) Another thing to be careful of is the "play" caused by using the Z handwheel as a surface that holds position. When you move over to CNC, Sherline provides a new leadscrew and leadscrew mount that provides a preloaded backlash free means of fastening the leadscrew to the axis. There's several photos and drawings in the files section of one person's way of building a preloaded Z axis for the manual mill. This might also be a worthwhile project. Jerry ------- Date: Mon, 05 Aug 2002 10:55:20 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry, It was making a cut along the long 3.5" X axis, and by the time it got to the right, it had dropped about 1/8". This is without any shift of the stepper. The cutting was in a critical area, a 1/8" thick flange. :-< It had been cutting fine before, but I think the tough raw edges of the casting might have aggravated it. It took me some time to figure out what was happening, by that time, the casting was "in the dust bin" (British casting). I have had that happen before, but not this severe. I had just nicely finished the other (bottom) side of the casting. I was through the "skin" of the casting, although I did notice a spot on one corner that "made more racket" when it cut, so I'm thinking it was a tough spot. I can get a replacement for the casting, but the real problem is curing the problem! I intend to carefully observe my new mill when it comes, and see if it could be that the 'Z' axis leadscrew is off axis, and is being pulled to one side at the bottom of the travel. Any thoughts appreciated. Alan KM6VV (wrecked my whole day) ------- Date: Mon, 5 Aug 2002 13:56:26 EDT From: joeb759x~xxaol.com Subject: Re: Re: Sherline Mill backlash and Fun with Moglice Hi Allen, I read your thread with interest as I also have had Z axis troubles. My 5400 mill is one year old with very little wear, if any. When I adjust the depth of cut on the Z axis and then lock the saddle nut while holding the handwheel to prevent it from turning, the depth of cut increases up to .010 at times. I don't know what to do to correct this problem as it varies from one setting to the next. I first noticed the problem after measuring my part. Then I placed a D.T.I. inthe spindle and you can see the increase in depth when I lock the nut. I would not even think of trying to make a cut with a mill cutter without the saddle being locked. I did it once but not twice! Wish I could have been of more help but as you can see I need a little of that also. Cheers, JoeB ------- Date: Mon, 05 Aug 2002 11:20:40 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Tom, Yes, That's what I think I'm seeing. It sure is infuriating! This hasn't happened for a while, but then, I've been using 3/32" endmills, not this 2 flue 1/4" endmill. As the 'Z' depth was set by the stepper (which is much bigger now), I DON'T put my hand behind to test the 'Z' axis (like I did WAY before I got the CNC). Too bad Craig's not available to reply! I could use a little advice right now! Alan KM6VV -------- Date: Mon, 05 Aug 2002 11:35:50 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry, A "wiggle"! Yes, I thought I saw that on last week's project just before it got down to the part, but couldn't see anything to cause it. And I was "spot on" for the parts made (well, except the one that the X axis "nut" got loose on). So your observed left->right movement might be an indication. I don't see the gib as being too tight (more like too loose?), In my case, but a worn saddle nut, or miss aligned Z leadscrew as being the cause. The stepper on the Z axis takes care of the handwheel "play", and I put a new leadscrew on the old Sears/Sherline mill when I made the conversion a few years ago. I never did like (or understand) the Z axis adjustment(s). Alan KM6VV ------- Date: Mon, 5 Aug 2002 12:44:17 -0600 From: "Jim Hall" Subject: Re: Re: Sherline Mill backlash and Fun with Moglice Allen, I'm very interested in this thread since I also have Z axis problems although not nearly as severe as what you have experienced. My 5400 Mill is only about a month old. When using the fly cutter, I have found that sometimes a downward Z axis change of a few mils would result in no actual Z axis movement (fly cutter wouldn't remove any material). I might do this two or three times with no Z axis movement. Then on the third or fourth time, the fly cutter would take a big cut. I was locking the Z axis each time. Measurement with a DTI showed that sometimes, after adjusting the Z axis, pushing down on the spindle assembly would cause an additional downward movement of 4 or 5 mils. Since the above experience, I have been putting downward pressure (with my hand) on the spindle assembly as I adjust the Z axis downward. This has reduced (maybe eliminated) the problem. However, I don't understand why the weight of the motor isn't enough to eliminate the problem in the first place. Maybe it's because the weight of the motor isn't directly in line with the Z axis lead screw and therefore applies a torque to it. I'll be interested to hear if anyone has ideas for possible causes or solutions to the problem. Jim -------- Date: Mon, 5 Aug 2002 11:52:17 -0700 From: "Dave Hylands" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice I expect that adding a counterbalance to the Z-Axis and/or moving the motor to the rear would help. I found some example mods to a Sherline Mill here: Shorter Version of link: Dave Hylands Vancouver, BC, Canada http://www.davehylands.com/ ------- Date: Mon, 05 Aug 2002 12:03:02 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Joe, Well after remembering what I saw on mine after Jerry mentioned his observations, and from what you're saying, I'd speculate that the saddle nut (the big square block riding on the Z axis) is tilting when you tighten the Z axis lock. I wish I had a Z axis lock! And I'm thinking that when my new mill gets here (it should have one), that possibly I can rig it so that I can run some CNC with it locked, and then do a "tool change" to allow me to loosen it for Z moves. Just an idea, I haven't worked out the details yet. The first thing to do is get zeroed in on Z axis adjustments! On my old mill, there are three points of contact with the saddle nut. One in the center is a 10-32 or so screw, and the other two (were) setscrews. These three points of contact are SUPPOSED to keep the nut running true to the leadscrew, without any unnecessary play. In my case, It SEEMS to be pulling the leadscrew over (at the bottom) if I set it up at the top, and so runs too loose. I don't know, I'm still trying to get it back into useable adjustment! Alan KM6VV P.S. Anybody know where a good description of this adjustment is? I've not been successful on several attempts to find it in the "adjustments" section. Cheers! -------- Date: Mon, 5 Aug 2002 12:07:36 -0700 From: gleex~xxica.com Subject: Re: Re: Sherline Mill backlash For what its worth, my Sherline has two long springs on it which apply a constant downard pressure to the spindle. This was done as part of the CNC retrofit that Bill Griffin did to my machine. Perhaps Bill can shed some light on why he did this. Eric ------- Date: Mon, 05 Aug 2002 12:58:37 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jim, Sounds like many of us have these problems! My motor (180 oz/in) on a Sherline CNC mount IS directly over the leadscrew, so I don't see why either. Jerry's "wiggle" observation suggests to me that possibly the saddle nut is getting "cocked" on the leadscrew, and thus takes a "nudge" (my rough casting?) to get it dislodged. I don't know! Ok Craig, we need you! Come back from vacation real soon! Alan KM6VV ------- Date: Mon, 5 Aug 2002 16:03:33 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash and Fun with Moglice Just as another point of reference. I have an approximately 1 year old Model 5000-CNC that has been used almost everyday for 5+ hours per day. I have NEVER had th problem that you are referring to. And I would be highly sensitive to this problem since I carve very small this in titanium with tiny cutters. An extra 0.005" on the cut will shatter my endmills. Am I just lucky and should I be worried about an upcoming event? Also, I hav never adjusted a single thing on the z-axis since I have been using it. Z-axis backlash is not a concern of mine since I am always downfeeding into the part, so I have never adjusted this axis. On the other hand, I adjust the x-axis backlash everyday before I start. Daniel J. Statman, Statman Designs www.statmandesigns.com ------- Date: Mon, 5 Aug 2002 17:15:32 -0400 From: "Carol & Jerry Jankura" Subject: RE: Re: Sherline Mill backlash Alan: I believe that Sherline's instructions are to move the saddle nut as close to the handwheel as possible, and then adjust the two set screws and hex cap screw so that there's "easy" motion when you turn the handwheel. Jerry |P.S. Anybody know where a good description of this adjustment is? I've |not been successful on several attempts to find it in the "adjustments" |section. ------- Date: Mon, 05 Aug 2002 15:36:56 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry: No, it's not excessive backlash, poor clamping, or the leadscrew turning. I'm using a 1/4" endmill in an endmill holder. The saddle nut "jumps" somehow! I'm still investigating. The 4017 part doc's describe a saddle nut adjustment. Might help, although I am of the opinion that the leadscrew's possible mis-alignment to the Z ways is part of the problem. Alan KM6VV ------- Date: Mon, 05 Aug 2002 16:12:03 -0700 From: Randy Gordon-Gilmore Subject: Z nut, was Re: Sherline Mill backlash The Z-axis nut is "held" to the carriage in a push-pull arrangement. The capscrew in the center is in tension, flanked by the two setscrews which are in compression. The Sherline instruction sheet is not very clear on the subject, but you can (and must) adjust both the lateral position of the nut, and its tilt or parallelism to the Z ways. When adjusted correctly, the Z-axis leadscrew should be positioned right down the center of the bore in the column, and running the saddle up and down its length won't push it off to one side or the other. By moving both setscrews together, you adjust the lateral position of the nut. By moving one in and one out (in minute but equal amounts) you adjust the "tilt" of the nut without disturbing its lateral position, and thus can make its axis parallel with the leadscrew's axis (that is what the instructions hint at by "minimum amount of drag") The center capscrew is mainly to lock down the adjustment provided by the two setscrews, but you can't tighten it too much or you just embed the setscrew points into the brass nut. The whole thing is pretty much a matter of balance and feel. The Sherline instructions say to move the saddle up close to the handwheel end of the leadscrew, but it is almost better to place it towards the free end, so it is easier to judge how closely the nut is holding the leadscrew centered in its bore (and then run it up towards the handwheel to confirm the adjustment.) On my mill and lathe (made years apart) there is a difference in distance from the nut mounting surface on the saddle to the column center of about .015" Thus the need for the adjustment for a "universal" replacement part. For my Moglice retrofit, I wanted a solid attachment of the nut to the saddle, and that is why I brazed shim material onto the nut so that the capscrew would hold it solidly to the saddle while having the bore centered on the leadscrew (which I held in place in the column with centering rings while I cast the Moglice) I had to put a shim on both the clamping surface, and the surface at right angeles to it, so the nut is solidly in the corner in the saddle. I don't think that this adjustment could account for your 1/8", Alan. There is not that much sideways play in the clearance hole for the capscrew, even if it was just left slack... The only time I have encountered a problem remotely similar to yours, is when I was milling with a 3/32" shank endmill and didn't tighten the collet enough. My cut was over 1/8" deeeper by the end of the cut than the beginning, purely from the endmill shifting in the collet! Best regards, Randy ------- Date: Mon, 05 Aug 2002 16:24:07 -0700 From: Randy Gordon-Gilmore Subject: Re: Sherline Mill backlash and Fun with Moglice 8/5/2002, Alan wrote: >Yeah, a counterbalance is a good thing, in fact, I have one of Randy's >old ones, except I can't mount it without limiting my spindle options. My counterbalance is only an extension of Alvaro Fogassa's motor relocation: http://groups.yahoo.com/group/sherline/files/sherline%20z%20axis.JPG He pointed out very correctly that having the motor weight centered on the ways would reduce friction (especially stick-slip "stiction") But surrouning the column with the spindle drive belt does keep you from being able to tilt the head too (not a problem for me, since I've been tweaking my mill as a single-minded CNC machine.) Best regards, Randy ------- Date: Mon, 05 Aug 2002 16:37:10 -0700 From: mark Subject: Z-axis backlash / unexpected movements 1. Take out ALL your gibs and take the rough spots off them with a nice, sharp file. Because they are a relatively soft composite material, they are compressible. If only 10 percent of the area of a gib surface is touching its corresponding way surface, it will be 10 times as compressible at a given pressure. Then, you will be able to adjust the gibs with far less "grab" for a given level of tightness. This isn't my idea, but it sure made an improvement in my mill. 2. Make sure the headstock and key are tight. Ditto for all the screws holding the ways to the mill column, mill column to base, etc. 3. IF, and only if, you have adjusted the z-axis leadscrew "tracking" with the two setscrews adjacent the lock screw on the z-nut, you can then adjust Z-backlash. In my opinion, it would pay to buy those radial needle roller bearings and washers for all handwheels, not just for the CNC version. This allows you to have lower friction between the handwheel and that silly 1-inch dia disk against which it bears, so that you can push the handwheel against it just a little bit more forcefully, and gain another thou or so in backlash reduction. I got mine down to a "few" thou. Shouldn't be 10 thou or above - but won't likely be 2 thou either. 4. The trick of putting a sawcut half way up the z-nut, then squeezing (or forcing apart) the two portions, is a great idea- not mine either. This has the effect of two opposing nuts, putting a portion of the leadscrew in either tension or compression, and one *should* be able to get down to a couple thou backlash without too great a friction penalty. 5. I discovered that high quality clock oil on the leadscrews makes quite a difference - a few inches/minute in a less-than-optimum-powered CNC situation. /mark ------- Date: Mon, 05 Aug 2002 16:47:38 -0700 From: Alan Marconett KM6VV Subject: Re: Z nut, was Re: Sherline Mill backlash Hi Randy, That's a pretty good explanation of the Z leadscrew and saddle nut! I AM of the opinion that there IS something going on that I'm not aware of! I'm not using a collet, I'm using the endmill holder (tight on the spindle's threads), but perhaps the endmill was "walked" down in the holder while I was cutting. It's a possibility. It could be a combination of the saddle nut getting loosened up by a little vibration (the rough casting), combined with the endmill walking (it didn't do it on the first side). I'll try to examine this whole thing some more as soon as I get time. I DO want to improve the adjustment of the saddle nut, 'tho. I can't afford to mess up another casting! Best regards, Alan KM6VV ------- Date: Mon, 5 Aug 2002 17:13:59 -0700 From: "Marcus & Eva" Subject: Re: Re: Sherline Mill backlash and Fun with Moglice Hi Alan: Are you SURE the Z axis is moving down??? One of the big problems that used to drive milling machine operators crazy (before carbide insert tooling was widely used to hog away material) was cutters slowly crawling out of the collets. Happens more with heavier cuts because the right hand spiral of the flutes exerts a large downward force on the cutter. I've seen guys milling pockets in injection mold bases and finding out that the pocket was 1/8" deeper at the end of the cut than it was at the beginning. Much cursing happened during those times, accompanied by scrapping thousands of dollars worth of blocks, or putting in underlay plates. An easy way to check is to mark the cutter with a felt pen when you start. Mark the column and the head too. You'll soon find out which bit moved when it wasn't supposed to. If it's the head that's dropping then, most likely, the Z axis slide is too tight. Check the gib and check the freedom of the z axis slide over its full travel by disconnecting the leadscrew from the nut and sliding the head up and down freehand. It should have the same drag top to bottom. If it doesn't, it's either burred somewhere or it's not parallel. Burs are easy to find and fix. Non parallelism requires replacing the ways. Cheers Marcus ------- Date: Mon, 05 Aug 2002 18:00:41 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Marcus, Yeah, I'm starting to suspect the endmill "walking" down in the endmill holder, after reading all the great posts we've had today. And your example of the castings (molds) certainly fits in. This IS a new two flue endmill, and a new endmill holder, and a new material (cast iron) for me to cut. Oh well! I'm still *LEARNING* (painfully $$). I did see some irregular behavior in the Z axis, so I'm inclined to think the Z axis leadscrew IS out of parallel, :<( too. And you say the only thing to do is replace the Z ways? OUCH! As the Sherline stepper motor mounts mount at a limited plate on the top of the Z ways, I'm wondering if it's possible to "true" up this mounting surface? I believe the problem existed way back in the late 80's when I was building robot parts (manually). I haven't confirmed that the lead screw IS out of alignment, but I suspect it is. :<( Cheers, Alan KM6VV ------- Date: Tue, 06 Aug 2002 00:20:14 -0000 From: "tollgrade" Subject: Z AXIS endmill problem. When using a endmill in a collar make sure you use the top of the flat surface on the end mill when tighten up the 10/32 setscrew. If you use any other part of the flat surface and the setscrew loosen up the end mill will slip down cutting more than you want. Caused me problems till I figured it out. Larry M. ------- Date: Mon, 5 Aug 2002 21:23:07 -0400 From: "Carol & Jerry Jankura" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice >I've seen guys milling pockets in injection mold bases and finding out >that the pocket was 1/8" deeper at the end of the cut than it was at >the beginning. Good Question. Alan - how do you mount your mills in the holder? With the lower end of the flat pushed against the set screw or the high end? If it's the lower end (closest to the workpiece), there's probably 1/8 inch of play to let the mill drop down. I think Randy's got the solution to your problem. Generally, I mount my mills so that they're pulled down as far as they'll go before I tighten the set screw. Jerry ------- Date: Mon, 05 Aug 2002 18:53:44 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry, At the low end. Is that wrong? I think it was Larry that was commenting on this, although I didn't quite get it (and perhaps still don't). WHERE are you clamping? I'd always thought you "backed up" the a bit or endmill against the shoulder, so to speak. It doesn't go IN any further that way (I'm cutting on the end). I hadn't thought of it PULLING OUT before. What is the 1/8" of play to let the endmill drop down? I'll check tonight to see if the endmill has shifted from where I clamped it. I've only had endmills push up (into) a collet before (only other time I've used my 3/8" endmill holder is for the Starret edge finder). This endmill should have been cutting on it's end, only a shallow cut (.005+), unless once it got started cutting on the side (or the tough edges of the casting), it continued deeper? And I didn't think there was anything to "learn" about an endmill holder. The saddle nut and leadscrew, and "all the usual suspects" will be examined thoroughly. Alan KM6VV ------- Date: Tue, 06 Aug 2002 02:01:59 -0000 From: "tauscnc" Subject: Re: Z-axis backlash / unexpected movements Hey Mark and Randy, great posts (still reading them all). From what I recall, Rich was the first one I read that sawed the Z axis saddle and then moved them apart to decrease the backlash. I tried this but was unable to and ended up breaking the saddle nut in half :-0. I later came up with my own way and have found that it's working well. It is also fully adjustable like Rich's. http://www.cuttingedgecnc.com/machinemods.htm (please go to the bottom). later tauseef ------- Date: Tue, 06 Aug 2002 02:29:30 -0000 From: "tauscnc" Subject: Re: Sherline Mill backlash Hey Alan, I just remembered, I am using a shim (broken piece of single edge razor blade, hey it works:) right at the base of the stepper motor mount to tilt it so its 90 degrees to the z axis. I orginally bought a manuel 5410 and converted it to CNC later. I would find no matter what I did, the saddle would stick at the top or bottom depending where I tightened it (it was smoothest in the middle of the leadscrew). I soon found (no saddle nut installed) when I tightend the stepper motor mount it would tilt causing the end of the leadscrew to be off by as much as 1/2 cm! After trying out some shims I got it to tighten down where I could not notice any leadscrew movement (you could file the end of the Z way to make it parrallel). Now its very nice. I also found this to be true on the Y axis and filed the end of the base just a bit (the X axis seems fine). tauseef ------- Date: Tue, 06 Aug 2002 02:35:35 -0000 From: "tauscnc" Subject: Mounting an endmill Hey guys, some very interesting information! I think I get it but want to be sure (and yes alan I'm with you, I didn't think there was much that I had to learn about endmill holders :-). I thought you wanted the endmill to be sticking out of the holder the least amount you could. When I use the 3/8" holder I put in the endmill, push it up as far as it will go, and then tighten the setscrew in the flat. Now I see, if I do this, when I am milling the endmill is *Pulled Out* in stead of being pushed in (makes sense) as it grabs on the material. Is this the right way? how about on Collets? Should i just put the endmill in as far as it will go and then tighten? thanks tauseef ------- Date: Tue, 6 Aug 2002 01:14:19 -0400 From: "Carol & Jerry Jankura" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice |At the low end. Is that wrong? I think it was Larry that was |commenting on this, although I didn't quite get it (and perhaps still |don't). WHERE are you clamping? I'd always thought you "backed up" the |a bit or endmill against the shoulder, so to speak. Hi, Alan: Generally, I pull the end mill down, so it's riding on the top edge of the flat. BTW, I checked my Z leadscrew. It was difficult to measure using a caliper, so I used the sheets in a pad of paper. The right hand side (as you look at the leadscrew from the back of the mill) of the leadscrew measures 0.116 inches from the RH edge of the circular groove that contains the leadscrew. This is true whether the saddle nut is at the top or bottom of the screw, indicating that the leadscrew is parallel to the way. The paper is nominally 0.0035 thick, so I'd guess that the tolerance on the measurement is 0.007 or so. |And I didn't think there was anything to "learn" about an endmill |holder... Amazing what we all have to learn, isn't it. I think that's one of the best things about this list - everyone knows something more than everyone else, at least on one question, so we continue to learn from one another. |The saddle nut and leadscrew, and "all the usual suspects" will be |examined thoroughly. I'll be interested in hearing your results. Jerry ------- Date: Tue, 6 Aug 2002 09:18:08 -0700 From: "Marcus & Eva" Subject: Re: Re: Sherline Mill backlash and Fun with Moglice >And you say the only thing to do is replace the Z ways? OUCH! Hi Alan: What I was referring to is worn WAYS, not leadscrew misalignment. What you need to do is isolate the possible sources of problems one by one. The easiest place to start is to disconnect the Z axis leadscrew, either from the nut, or from the top of the ways. Then you can check the Z axis movement for smoothness. Drop the Z axis down as low as you can, and snug up the Gib until you can just smoothly slide the head. (I use the bottom of the Z axis for reference, because it's most likely to be worn from having chips slapped against it all its working life.) Now try to run the head all the way up just by pushing on it. If it won't go evenly, you have enough column wear that you can't adjust the gib to a position that's tight enough to prevent rattle at the loose places and sticking with unpredictable movement at the tight places. If all checks out at this step, then you can move on to the next step with confidence. While you're here, by the way, check that the cross hole in the gib is nice and snug on the locking wire, and that the setscrew holding the wire is nice and snug. (A loose gib will act as a wedge, and jam the slide occasionally.) The next step is to assess sources of unwanted movement in the leadscrew and nut assembly. The normal condition is that the weight of the head holds the nut down against the screw and is restrained from dropping by the screw. Of course, the nut is supposed to be a rigidly connected part of the head. If it's not, you will get an effect similar to that which you'd have with a worn nut...ie excessive backlash. Looseness in the mounting of the nut to the head is NOT likely to make the head stick and drop,(unless the gibs are too tight too) but it will make the whole head bounce around when a moderately heavy cut is attempted without locking the head to the Z axis ways. The next thing to check is the amount of looseness in the mounting of the leadscrew to the Z axis ways. Looseness here will also manifest as excessive backlash and will have the same consequences as a loose nut or a worn nut. The head will hop around under heavy cuts if it's not locked. The next thing to check is whether the leadscrew and nut are axially aligned. The easy and really only relevant way to do this is to run the head all the way up with the nut loosened slightly (so that it can find its own alignment. When you've reached the top of the stroke, snug down the nut. If the assembly runs hard, the nut is in the wrong place and is trying to bend the screw, or else the screw is canted relative to the ways and needs to be realigned by filing the top of the ways and deburring the mounting surfaces. I'd be very surprised if the screw is out of axial alignment, because the operation to make the seat is easy to do accurately, so it's difficult to imagine how the factory could screw it up. Misalignment of the screw is easy to see and the criterion for precision is not too high. Typically, the screw will wiggle a bit, side to side at the free end, and this is perfectly normal. The best way to fix nut misalignment, is to pot the nut in something like JB Weld. Open out the nut mounting holes a bit, so that there is no chance of the mounting screws hitting the sidewalls of the nut, and pulling it out of alignment. Clean and degrease the mating surfaces of nut and mounting seat on the head. Lube the mounting screws with grease. Slap on the JB Weld and assemble the nut to the head with the head at the TOP of its stroke, and the leadscrew securely in its proper position. DON"T reef down on the mounting screws...you want the nut to self align to its best position. Once the JB Weld is hard, you can tighten down the screws. Alan, these are really the only things that I can think of that could contribute to the problems you and others have experienced. One last thing to watch though...If your head runs very free on the ways and you are taking heavy interrupted cuts (such as using a flycutter) you can rattle the head down just from the harmonics shaking the screw and rotating it. So with a manual mill you really should lock the Z axis when you're taking a heavy bite. With a stepper driven rig, the motor will hold the screw immobile until you command a move. Hope all this helps Cheers Marcus ------- Date: Tue, 06 Aug 2002 10:20:30 -0700 From: Randy Gordon-Gilmore Subject: RE: Z-axis backlash / unexpected movements 8/6/2002, Kevin P. Martin wrote: >Someday I want to replace it with a nut mounting that attaches >to both sides of the saddle and adjusts using the usual >sloppy-clearance-hole method. It will take some care to arrange, since you need to adjust both side-to-side and front-to-back as well as the parallelism of the bore to the column axis. All are subject to tolerance stackup of the assembly. The cantilevered mounting is plenty stiff enough, if you can get solid metal-to-metal contact between the nut and saddle. An alternative to what I did might be to adjust the current nut, then smear in some JB weld or similar as bedding compound behind the nut. Best regards, Randy ------- Date: Tue, 06 Aug 2002 12:24:06 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry, Well, I did some detective work last night, and found a few things: With out touching things, I got .035 on the left side top of the lead- screw, and perhaps .055 at the bottom. It was visibly not in alignment. With the leadscrew pulled out, I could observe quite a bit of slop in the saddle nut on the threads, so I figure it's shot (and I had already purchased a new one when I got the backlash stuff for the X axis a few months ago). I couldn't tell if the endmill had pulled out, but it had no flat. It could have contributed to the problem. Not a good situation, I'll add a flat. The top end of the Z ways where the Sherline CNC motor mount bolts on is not really a finished surface. It has wide tool marks. The "original" Z axis handwheel drive round body mounts by one countersunk screw from the back, and there is no contact with the top end of the ways, just the round body contacts the ways. With new saddle nut installed on the Z axis leadscrew (no slop now!), I noticed that I could move the motor mount around a little, and thus I found a "sweet spot" where the Z leadscrew was parallel (by dial caliper). I also found that I could run the saddle nut up tight against the Z carriage, and keep the leadscrew parallel to the ways. I basically aligned it "backwards", that is, I matched the top position of the motor mount to agree with the bottom (parallel)! The saddle nut is not in the center (is this a problem?), but it runs up and down smoothly. I might experiment with it more. Do the new mills that are "CNC ready" (as far as the holes for the motor mounts) have this top end of the Z ways finished? I haven't cut any parts with it yet, but it's better then I've ever seen it before! (musta learned something.) I don't see how clamping at the top of the endmill's flat is any better, unless the flat is tapered (must be a reason)? I should think having the minimum length of the endmill extended from the holder would be best, same as for a collet. Thanks guys! Alan KM6VV ------- Date: Tue, 6 Aug 2002 16:25:11 -0400 From: "Kevin P. Martin" Subject: RE: Re: Sherline Mill backlash and Fun with Moglice Alan Marconett KM6VV [KM6VVx~xxarrl.net] wrote: >The top end of the Z ways where the Sherline CNC motor mount bolts on is >not really a finished surface. It has wide tool marks. I ran into this installing my CNC retrofit. No matter how I adjusted the saddle nut, there were tight spots in the motion. I did not notice the cause of this until a few weeks later when I was investigating why my Z leadscrew had snapped next to its bearing. The top end of the Z ways was rough and out of square--it looked like a bandsaw or cutoff-saw cut. The angled bearing meant the screw was flexing continually, effectively acting as its own universal joint! Metal fatigue quickly set in. I explained the problem to Craig, got a free replacement leadscrew, and milled the end of the ways square on my lathe. I seem to recall him saying that earlier production did not have the machined end on the Z ways since it was not originally a reference surface for mounting other parts. Kevin Martin ------- Date: Tue, 06 Aug 2002 13:35:28 -0700 From: Randy Gordon-Gilmore Subject: RE: Re: Sherline Mill backlash and Fun with Moglice 8/6/2002, Kevin P. Martin wrote: >I seem to recall him saying that earlier production did not have the >machined end on the Z ways since it was not originally a reference >surface for mounting other parts. Yes, on both the manual mill and lathe the leadscrew is mounted to a flanged sleeve that registers in the bore in the column/bed. (So does the drill jig for the stepper mounts for that matter, which is why I take the "default" position of the leadscrew to be centered in the bore...) I guess I was lucky--both my mill and brass-bed lathe had good square ends on them, and it never occured to me that it might have been otherwise. It would be good for Sherline to mention this possibility in their CNC conversion instructions. Best regards, Randy ------- Date: Tue, 06 Aug 2002 14:42:45 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Marcus, Thanks for all your thoughtful and considered answers! Luckily, I don't think my ways are worn, although I DID find a worn saddle nut. And as I posted earlier, I also did determine that my Z axis leadscrew was out a little, and was able to bring it in. I didn't really start at the ways and gib's, so I might just go over it all again. They seem to be moving nicely with the stepper at this time, although with the weight of the spindle and stepper, I couldn't get a good feel for how "easy" it would glide. Much easier to feel it in the X or Y axis. I DO see considerable improvement after replacing the saddle nut and adjusting, hopefully this will work better! Cheers, Alan KM6VV ------- Date: Tue, 06 Aug 2002 15:26:24 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Jerry, Couldn't the endmill still move down? Although it might get free of the setscrew. That could cause some problems! Is there some reason that the endmill no longer can move downward if clamped at the top? That's what I don't get. I'm all for keeping it from going DOWN! I'm almost wondering if the flat on the endmill shouldn't also be a bit of a V grove, such that the setscrew prevents movement along the axis as well as preventing any rotation. Alan KM6VV ------- Date: Tue, 06 Aug 2002 15:42:35 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash and Fun with Moglice Hi Kevin, That supports my suspicions! And yes, it DOES look like a cutoff-saw cut. I think I got around it this time. I did not notice it when I originally mounted the Sherline motor mounts. And trial fitting my old Z axis leadscrew while doing my "detective work" this time demonstrated that the manual handwheel drive didn't use that surface for contact (it didn't touch it). It didn't need to. I suppose it would be appropriate to go back and mill or file it off, but I believe I've got it working now. Thanks for the comments. Alan KM6VV ------- Date: Tue, 06 Aug 2002 17:53:34 -0700 From: Alan Marconett KM6VV Subject: Re: Z-axis backlash / unexpected movements Hi Randy, OK, 40910 (which I can't find on the exploded view) is called the Saddle, and I did find a "saddle gib", so it follows that what I might have called the "Z axis carriage" in my ignorance is properly called the saddle (and it probably corresponds on the lathe). I did remember to call the part I replaced a "saddle nut" (probably because I ordered one last month). I was just anticipating the possibility of more parts in the newer model! Best regards, Alan KM6VV ------- Date: Wed, 07 Aug 2002 03:00:16 -0000 From: "luisguillermo98" Subject: Re: Sherline Mill backlash and Fun with Moglice This is what I do: I loosen the gibs a little bit and keep the saddle lubricated so the motor can do its job with the weight. After that I have not had any problem at all. Also you can put some extra weight directly on the spindle to keep the spindle on the bottom of the backlash. ------- Date: Wed, 7 Aug 2002 15:44:07 EDT From: joeb759x~xxaol.com Subject: Re: Re: Sherline Mill backlash Alan, I think that the problem has to do with the backlash between threads in the Z axis. As you dial in a setting for depth the axis screw is pulling the head down. When you stop the downward travel you still have the backlash area between the threads giving play in the downward direction. Hence when you begin to cut without locking the axis nut the head will drop that amount. Most often it will also drop when you lock the saddle nut also. I have found that by dialing in a greater cut (.015 instead of what I want .010) then backing up on the setting to the .010 needed does eliminate this problem. I'm still fooling with it, seeing how it goes. Joe B ------- Date: Wed, 7 Aug 2002 16:45:32 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash absolutely correct! When dropping down to the depth you are moving the headstock with the bottom of the threads since the threads of the leadscrew are pushing downward. The backlash is the difference between the location of the bottom of the threads and the top of the threads relative to the saddle nut. As you cut the weight of the headstock will randomly shake itself as low as it can go, to the top of the threads. So what to do, measure the backlash and drop the cutter to the desired point and then back up the handwheel the amount of the backlash, then lock the saddle. Let me know how this works. Daniel J. Statman Statman Designs www.statmandesigns.com ------- Date: Wed, 07 Aug 2002 14:36:38 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Joe, As I mentioned in yesterday's post(s), basically I found a worn saddle nut, and misalignment of the Z axis leadscrew. And I'm sure the endmill in the endmill holder contributed to the "digging in" I experienced. I'm setting the Z depth by the CNC's control, and typically over the part. So as I plunge down, I can't very well go deeper, and then back it up. If I've started the Z axis above the part, and then moved down, then I HAVE "ran out" the backlash. The top surface of the part is "touched off" in Z, and the backlash is thus "ran out" in the downward direction. What I understand you to describe would seem to invite backlash or contain backlash. I've always heard that you remove the backlash by moving IN THE DIRECTION of the cut first (start far enough back so that upon getting where you want to be, the backlash is out). I cannot lock the saddle nut, as all axis are under CNC control. The Stepper motor holding torque and weight should hold it there. And what if one is doing a compound move? Then the Z axis may very well be following a contour, and obviously cannot be locked. Both my X and Y locks are REMOVED from my old Sears/Sherline mill (the old gal never had a Z lock). Hopefully my replacement of a worn out saddle nut, and the realignment of the Z axis leadscrew (now that I understand it a little better) will eliminate THIS problem from my milling. It should be noted that for most users unfamiliar with Sherline's endmill holder (as was I) that the endmills CAN pull themselves down INTO the work. I haven't heard, is this also a problem with collets? The 3/8" and larger endmills with Weldon "flats" apparently need to have the setscrew set against the UPPER taper on the end of the flat (I just learned this, thanks guys!), not just anywhere. I checked in my garage this morning, and sure enough, on a 3/8" endmill for the RF-31, there is a Weldon flat on it! I have no idea where I clamped it down in the R8 endmill holder for the RF-31. And I've been MISTAKEN, I've only used a 1/4" endmill holder (my brand new one) on the Sherline! Seems the only duty the 3/8" endmill holder has had on the Sherline mill is to hold the Starrett edge finder! So although I've been saying (from a failing memory) that I clamped on the flat of the endmill, actually I had really used a 1/4" endmill, which HAS NO FLATS, let alone a nice Weldon flat! Sorry about the false report. Perhaps I can grind a Weldon flat on the 1/4" endmill? OTHERWISE, I'm a bit puzzled, because the endmill holders are made very accurate, and as soon as I clamp down on a round shaft with a setscrew, I'll never get it out again! Yesterday I posted Sherline's list of new endmill holders for smaller size endmills, but I see a problem, HOW DO YOU CLAMP the endmills, Center drills, etc. into them? The edgefingder is fine, it doesn't really need to be "CLAMPED" in tightly. Thanks for the comments, do let us know what you work out Joe. Alan KM6VV ------- Date: Wed, 07 Aug 2002 15:04:27 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Jerry, Yes, that would probably have been better. I have used collets up 'till now, and thought I was going to have a superior setup by using the endmill holder. Might have been, if I'd used an endmill with the Weldon flat on it. I have had collets get loose during machining, because I didn't tighten them up enough (and severe vibration can loosen them too). Alan KM6VV ------- Date: Wed, 7 Aug 2002 15:36:32 -0700 From: "Dave Hylands" Subject: RE: Re: Sherline Mill backlash > What I understand you to describe would seem to invite backlash or > contain backlash. I've always heard that you remove the backlash by > moving IN THE DIRECTION of the cut first (start far enough > back so that upon getting where you want to be, the backlash is out). This would normally be true, and works well in a horizontal plane. Normally, on a lathe, there's nothing that will try to pull the tool bit into the part, rather the forces are pushing the toolbit away from the part. However, on the Z axis on the mill you have two forces working against you: 1 - Gravity. Since you're pushing the axis down, if everything is tightened up, it's possible that the saddle will be at the "top" of the backlash, rather than at the "bottom". Once you start milling and vibration sets in, gravity helps to let the saddle settle into the "bottom" of the backlash. 2 - End mills will try to pull themselves into the part. I was using a 1/4" endmill the other night, and had not tightened the set screw with the endmill all the way down. I happened to be looking at the endmill at just the right moment and actually watched the endmill suck itself deeper into the part. Sure enough, when I stopped and checked the endmill, the set- screw had loosened a bit and the endmill was down as far as it could go. Fortunatly, I still had lots of metal to eat away and it wasn't cause for a scrapped part. So, I'd speculate that if the gibs are too tight, then the head won't fall to it's lowest position naturally (due to gravity) and vibration may cause it to drop further once milling has started. If the gibs are loose enough, then the head should always ride at the "bottom" of the backlash. I don't know if this will cause other problems or not. You should be able to tell if this is the case by checking to see how much force is required when you change directions on the Z-axis handwheel. Get a feel for how much force is required on the handwheel when moving the head upwards. Then move the head downwards (should require less force). Then change to moving upwards again. Does it immediately require the same amount of force as when moving the head upwards? Or is there a couple thou where it's really easy to turn? If it's the latter, then gravity can pull the head down that extra couple of thou when the mill is operating. Dave Hylands Vancouver, BC, Canada http://www.davehylands.com/ ------- Date: Wed, 7 Aug 2002 20:27:33 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash Alan, I really think you are overlooking the obvious cause of the Z-axis dropping 0.005-0.010" during a milling cut. It is the backlash. You are not considering the pull of gravity and the potential pull of the endmill into the material. This type of DOWNWARD motion backlash is not "taken up" by your downward move. A downward move takes up the UPWARD backlash. If you think about the v-shaped space of a thread when you move downward you are rubbing the top of the "v" against the threads of the saddle nut. Therefore with gravity acting downward it is possible for the z-axis to shift to the bottom of the "v" by the amount of your backlash. All of your misalignment of the saddle nut and leadscrew may contribute to other problems, specifically accuracy of your moves if not moving perfectly parallel to the Z-axis ways. But why would any of it cause the headstock to drop. If you were the one see 1/8" drop then check your endmill before and after the move and see if the same distance is sticking out. If you drop 0.005-0.010" then it is backlash. Tightening of the gib may prevent the drop. Or backing the stepper out by the backlash amount right before you cut will also do it. It seems counter-intuitive, but this must be what everybody is seeing. Dan ------- Date: Wed, 07 Aug 2002 17:51:21 -0700 From: Dave Martindale Subject: Re: Digest Number 839 >What I understand you to describe would seem to invite backlash or >contain backlash. I've always heard that you remove the backlash by >moving IN THE DIRECTION of the cut first (start far enough back so that >upon getting where you want to be, the backlash is out). It's more complex than that. The advice you quote is the right way to avoid backlash on the cross slide of a lathe, where the toolbit will "push back" against the leadscrew once cutting begins. It's also correct for "conventional" milling, where the cutting forces push the table back against whatever leadscrew (X or Y) is providing the feed. But it doesn't work in a "climb milling" situation, where the cutting forces tend to *pull* the work into the cutter without the help of the leadscrew. If you have .010 backlash in the leadscrew providing the feed, then the cutter can move the work .010 all at once as the leadscrew goes from pushing the work to holding it back. With the Z axis, you're probably not actively feeding in Z while cutting. But the cutting forces from a normal right-hand spiral end mill want to pull the end mill down into the work, and gravity wants to pull the headstock and motor down too. So if you lower the Z axis and then stop, you've probably pushed the head down with the leadscrew and it can drop further by the amount of any backlash present. That's the problem. One fix that someone suggested is to overshoot in lowering the head and then bring it back up enough to ensure that the leadscrew is lifting the head, and so is prepared to resist downward forces. This doesn't work if there's no place where you can let the endmill drop too far before raising it. Another was to lower to the desired position, then crank backwards just enough to remove the play, but not enough to lift the head. This is probably not practical for CNC where the computer has no torque "feel" from the Z axis drive. Another was to use large springs (strong enough to overcome jib friction) to pull the head downwards at all times, so the leadscrew is always providing a "lifting" force on the head, even when it is being lowered. This method would work even if the Z axis is being driven during machining to follow a contour. The final option is ballscrews and nuts that have no backlash. Dave ------- Date: Wed, 7 Aug 2002 18:11:56 -0700 (PDT) From: Nhut Le Subject: Re: Digest Number 839 I agree that all the discussed factors contribute to the problem at hand, but no one (or I may have missed it) has brought up the role of the Z-axis handwheel. If this isn't kept in check, this could account for the .010 drop in the Z-axis. I've noticed over time that the little setscrew holding the handwheel to the leadscrew will slip and causes the leadscrew to drop lower, introducing even more backlash. Sherline acknowledges this and has instructions to fix the problem: http://www.sherline.com/Zaxisfix.pdf Nhut ------- Date: Wed, 07 Aug 2002 18:21:21 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Dan, Dave, Thanks again for the explanations. I hadn't been able to visualize gravity as being able to force a cutter further into the work then the stepper. So you both are saying that the 2 or 3 pounds of gravity will essentially add onto the cutting forces, which must be several hundred pounds, and move the cutter further into the work then the stepper does? Hard for me to visualize. But then, I've only thought of backlash while in the horizontal plane (as someone pointed out). Probably from my first lesson on an old South Bend lathe. "Always approach the work piece from a distance far enough away to run out the backlash". Or words to that effect. Hopefully I can improve over this last endmill example by using an endmill with a Weldon flat (3/8"), or going back to the collets. Should I also go back to 4 flue endmills for steel (cast iron)? Seems I just read that today in Sherline's "Vertical Milling Machine Operation". I THINK I've greatly improved the Z axis setup, and of course I've replaced the worn saddle nut. Dave's and Marcus' examples of checks to make for a manual mill may persuade me to remove the stepper, lay the mill on it's side, and experiment more with the gibs (I thought of putting it on it's side, as then gravity is out of the equation). The head dropped probably 1/8", and I don't belive there was that much backlash in Z at the time. Your .005" - .010" I could accept. Have I done enough? Will these steps prevent this from happening again? I really don't want to trash any more work like this! I'm tempted to "load up" the Z axis by increasing the gib tension, and somehow add another nut to limit the leadscrew backlash to the point of causing more friction on the saddle nut, to prevent gravity and vibration from doing as you describe. Best regards, Alan KM6VV ------- Date: Wed, 07 Aug 2002 18:33:06 -0700 From: Alan Marconett KM6VV Subject: Re: Z backlash Hi Dave, Yeah, I'm learning that it's a little more complex then my simplistic quote. I just responded to Dan and Dave H.' fine emails which are in agreement with yours. I believe it was Joe that was describing "coming from below" to get the leadscrew loaded up correctly, although I don't see how to do that with CNC. I am considering adding a second nut, and spring loading it to try to force out any backlash. The "climb milling" example is a good one. I HADN'T EVEN thought of it that way. You mention strong enough springs to override gib friction, why not just INCREASE the gib friction, to prevent it from falling? NO? Best regards, Alan KM6VV ------- Date: Wed, 07 Aug 2002 18:38:10 -0700 From: Alan Marconett KM6VV Subject: Re: Z backlash Hi Nhut, The Z handwheel is not a problem in my case, the handwheel is down in a drawer. ;>) I experienced the 1/8" drop while under CNC control. But your point is well taken. I think when I had a similar problem in manual operation (much before this CNC conversion, and I CERTAINLY didn't understand it then), I used my hand to tension the head, as someone has suggested. Alan KM6VV ------- Date: Wed, 7 Aug 2002 21:32:42 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash August 07, 2002 "Alan Marconett KM6VV" wrote: > So you both are saying that the 2 or 3 pounds of gravity will > essentially add onto the cutting forces, which must be several hundred > pounds, and move the cutter further into the work then the stepper > does? Hard for me to visualize. Alan, why would there be several hundred pounds of cutting force? Imagine if you have the milling headstock positioned over the work piece with a spinning endmill. If you could hold the headstock perfectly straight in your hands and lower it onto the work piece, and stabilize it from moving sideways at all (this is what the z-axis ways are doing. the force of gravity alone on a spinning cutter will tend to drop it into the workpiece and drill a hole with the endmill. once you have spun the cutter several revolutions all of the material is gone from under the cutter and it can drop again due to gravity. Only when it hits a physical stop will it stop dropping, this physical stop is the top surface of each leadscrew thread. Remember also that the side loads do not contribute to any of this since we are only concerned with the vertical vector component. The only things contributing to this vertical component are gravity, the leadscrew forces, and the potential for the cutter to grab the work in certain types of milling and certain materials. It is also a simple matter to program a backlash reducing upward z-axis move in a cnc program. With TurboCNC which has backlash compensation you just have to give a move 0.000250" above your bottom point. This will take up the backlash and not move your stepper (if you set the backlash compensation to be 0.000250" under the actual value), or you could probably live with the 0.000250" error. This is the amount of movement from a single step of a 1.8 degree motor with a 20 TPI leadscrew. Dan ------- Date: Wed, 07 Aug 2002 18:47:31 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Dan, You're right of course! If there is no downward cutting force (the Z axis is not moving), then it all starts to make sense! And of course the forces at right angles can't be added in either. The Z axis is free to float, and this explains why gravity is enough. I think I've finally got it! However I "fell" a lot further then .00025" (or is it .000125", as I halfstep? Microstep drivers?), that I don't have a problem with (I probably wouldn't even know it)! But 1/8"? That's a killer! Are you saying just to a move up by .00025 AFTER moving down to remove this backlash? Alan KM6VV (I've gotta add backlash comp. to my code...) ------- Date: Wed, 7 Aug 2002 21:45:26 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash If you tell the controller to move up the equivalent of 1 step, whatever that amount is (I think it is 1/4 of 0.001" since there are 400 steps per revolution when half-stepping) then the controller ACTUALLY moves the programmed backlash amount PLUS 0.00025". This will remove your backlash and only slightly alter your height, if at all. OTOH, if you set the backlash compensation to be 0.00025" less than the actual amount then it will be dead-on when it moves up the COMPENSATED 0.000250" Of course, you can't really measure anything this closely anyway. Dan ------- Date: Wed, 7 Aug 2002 18:50:58 -0700 From: "Dave Hylands" Subject: RE: Re: Sherline Mill backlash Hi Alan, I think that if you move up after moving down, you still run the risk of the cutter going too deep at the point that the Z-axis is being lowered. If you've measured the amount of backlash ahead of time, you should be able to stop that much short of the actual dimension, and let the backlash take out the rest of the way (I'm speaking from a purely theoretical standpoint, since I don't have my CNC working yet). I don't think that the amount of backlash is related to how for the leadscrew moves with a single step. It has more to do with wear and how well threads mesh together. Dave Hylands (who is also intensely interested in this particular topic) ------- Date: Wed, 7 Aug 2002 21:48:45 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash I forgot to mention, as I found out yesterday when I stripped my saddle nut. It is very possible for there to be 1/8" of backlash in a badly worn saddle nut and leadscrew. Especially on the z-axis where there is no anti-backlash nut. I use one of my manual Sherline lathes for rough cutting only and it has at least 0.075" backlash. I just do not care at all. When the leadscrew stops moving things I will replace it, and still not care. Leadscrews and saddle nuts are dirt cheap. Dan ------- Date: Wed, 7 Aug 2002 21:55:25 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash Dave, I understand that you are not running CNC, so I thought I would explain how it works a little more clearly. When you tell the machine to move down 0.050" into the part, it will move EXACTLY 0.050". If you have backlash compensation (and it is set to 0.010") then you tell the controller to move up 0.00025", the machine will move 0.0102500". This is the compensated backlash amount plus the amount of the move. If you measure the backlash and it is 0.00875" then the compensation will move that exact amount every time the direction of movement changes. So if you set the compensation on the z-axis slightly smaller than the amount of backlash you have when you command the upward move, nothing changes with the cutter and workpiece, but the backlash is removed. And it all happens in a fraction of a second with perfect accuracy and repeatability assuming your machine is set-up correctly. if however, you are doing some complex 3-D shape that required the upward movement of the cutter as it was cutting then you would need the exact backlash amount to be input. And, realistically if you need precision 3-D contours, then you aren't using a Sherline. Dan ------- Date: Wed, 7 Aug 2002 21:58:02 -0400 From: "Dan Statman" Subject: Re: Re: Sherline Mill backlash Download TurboCNC and give it a try. Or, if you are always milling down to the workpiece then you do not need automatic compensation, just program an upward z-move equal to your measured backlash right after the downward z-move, simple solution. You can even do a replace function in a word processor on your g-code files to take care of this automatically, or write a simple macro. Dan ------- Date: Wed, 07 Aug 2002 19:14:41 -0700 From: Alan Marconett KM6VV Subject: Re: Sherline Mill backlash Hi Dave, Dan, I wonder how I EVER got anything cut right in Z before! If the head doesn't drop because of gravity, then cutting down in Z shouldn't involve any backlash, as you are always cutting in the same direction. I know there IS gravity and endmills DO get pulled into the work. Perhaps if I take light enough cuts, so as not to wake up gravity, I'll have less "Z axis drop" to worry about. And I DID find a very worn saddle nut. I really think we should work on a backlash nut for Z, now that I realize we don't have one! Yeah, I like Dan's lathe example. Lotsa backlash, but who cares! You automatically remove it when you back off a tool, move it, and then travel back into the work. No worries! But then, putting CNC on a lathe still seems foreign to me, as it is difficult to predict where the cutting tip will be. I did learn that they use "standard" cutting tips, and they set them up with microscopes. I don't think I'm ready to CNC my 5" lathe yet. And I'm more inclined to agree with backlash having "more to do with wear and how well threads mesh together", otherwise we'd all have .000125 backlash! Alan KM6VV ------- Date: Wed, 7 Aug 2002 19:12:14 -0700 From: "Dave Hylands" Subject: RE: Re: Sherline Mill backlash Hi Dan, That makes sense - i.e. that every time the direction changes then the compensation would kick in. But that still doesn't factor in gravity. I would expect the backlash compensation algorithim to be slightly different for the Z axis than it is for the X or Y axis. For example, if you move the z-Axis down and stop moving (not change directions) you still need to compensate for backlash. So, a move in the downward direction followed by a stop should be considered a "change of direction". Dave Hylands ------- Date: Wed, 7 Aug 2002 19:20:35 -0700 From: "Marcus & Eva" Subject: Re: Re: Sherline Mill backlash Hi Dave: You've nailed all the important points perfectly. On a bedmill (Head moves up and down) the smoothness of the Z axis motion over the whole Z axis travel is important to allow the head to sit at all times on the bottom of the backlash. Worn ways will make the head stick in places and rattle in other places. With regard to endmill holders and plain collets for gripping endmills, cutters will pull out of either system. That's why the Brits developed the Autolock collet system that's used with threaded shank cutters. It's effective to prevent pullout but it's a royal pain in the ass to use, mainly because you can't clamp anything else and you can't control the depth to which you clamp a cutter. The only ways to get around the pullout phenomenon is to either use a positive clamp system like the Weldon flats on plain shank cutters as described already, or use the Clarkson or Dormer Autolock setup. For my own use, I do all my hogging with insert carbide tooling. The spiral angle on these cutters is so low that they generate little downforce and can be clamped with confidence in a plain collet even for hogging. The other thing I do is to avoid massively deep cuts. I find, (particularly with CNC) that I get a better job faster with shallower cuts at higher speeds. I rarely take more than 0.075" per pass in steel even with my Haas that has 7 1/2 ponies to make it go, and I find that my cutters stand up better, the machine doesn't hammer and howl, and the job is more accurate. I take full advantage of the spindle speed I have and crank the feedrates right up. I'm using small ER20 spring collets in CAT 40 holders, and I don't need to squeeze the piss out of them to clamp the cutters. I know lots of jockeys who beat the stuffing out of the machine spindles and collet chuck nuts with big lead hammers and then try to bury an endmill one diameter deep into the job. The tools get wrecked, the job looks like it was chewed out by a beaver, and the cutters still suck out of the collets and end up either snapped off or driven right through the stock and into the table. With just a little bit of finesse, none of this is necessary. Cheers Marcus ------- Date: Wed, 07 Aug 2002 19:24:15 -0700 From: Alan Marconett KM6VV Subject: Re: backlash > There is a gentleman here that has fixed this very concern. >He has a web site that gives us a "How to do it", only thing is, >I cannot remember who it was, Hi Smitty, That would probably be Tauseef, I think I was just looking at his Sherline tip a few days ago. I couldn't reach his website a few minutes ago with the URL I'd bookmarked. Seems like something to look into. My old Sears/Sherline mill didn't have one. I'm assuming my new one will. Tauseef had a plate such that the lock could be pinned in "halfway" position as you describe. I'd like to add spring tension of some sort. Too bad it's a LEFT HAND internal thread on the nut and lock! Alan KM6VV ------- Date: Thu, 08 Aug 2002 03:06:09 -0000 From: "tollgrade" Subject: Z Axis adjustment procedures for CNC machines The follow list is documents from SHERLINE for adjusting the Z axis. http://www.sherline.com/6700inst.htm also the ASSEMBLY AND INSTRUCTION GUIDE for the gib adjustment. For Tauseef modification goto http://www.cuttingedgecnc.com/machinemods.htm for his idea which remove the end play in the saddle nut by adding the Z-axis locking lever which is not equipped with CNC machines. Larry M ------- Date: Thu, 08 Aug 2002 03:31:04 -0000 From: "tauscnc" Subject: Re: Z Axis adjustment procedures for CNC machines Hey guys, man, lots of stuff on backlash. There are 2 ways that I know of to control Z backlash, Rich's and mine. Rich's can be found in the files section or: http://groups.yahoo.com/group/sherline/files/Rich%20D%27s% 20Views/SaddleNutSplit.jpg mine again: http://www.cuttingedgecnc.com/machinemods.htm The saddle locking level is not included with cnc but is only like $8 or so. The material is simple to drill through and even simpler to tap. Just make sure you put it on upside down, so that little hole where the ball would fit faces UP. This way you should be able to tighten down on it fully within the Z way. It's quick, easy and cheap. Mostly its adjustable and I have found it to work out quite well on my mill. As for the page not loading, wonder if the server I use was down or something? ummmmmm Either way, Z axis needs a backlash control and sherline should start thinking about this. later tauseef ------- Date: Wed, 07 Aug 2002 22:13:27 -0700 From: Randy Gordon-Gilmore Subject: Mogliced Sherline backlash report Tonight I had a chance to measure the backlash on my Mogliced Sherline mill. I have a Starrett Last Word 15-0-15 indicator, which I held in the spindle using the 3/32" collet. I'm using CNC Pro, which has fast, slow, and incremental jog. I set incremental jog to .010" First I turned the point horizontal and slow jogged the Z down until the contact point (sphere) touched the table by about .005" for preload, and zeroed the dial. I switched to incremental jog and jogged down a commanded .010" The dial then read .010". I jogged up one increment, and the dial read .001" So the Z backlash is .001" I jogged up and down one increment, and the dial read .000" (i.e. showing .001" backlash again in the other direction, canceling the original backlash accumulation.) I repeated this several times to verify that this was a repeatable reading. So the Z backlash is .001" I did the same for Y, getting .001" backlash. On X, the backlash is .0025" I'm very happy with the .001" Y and Z backlash, and pretty happy with the .0025" X. I'm assuming that I was more generous with the release spray than Ron Ginger was, who reported less than a thou backlash on his machine. CNC Pro has backlash "compensation" so I will enter these numbers in the program before I start using the mill again. Once I get some kind of ability to mount the indicator to the gantry's Z axis, I will do the measurements there. It is scary fast--300ipm rapids with CNC Pro on my 466MHz Celeron. I was unwilling to go faster, and will probably "keep" rapids to 100ipm. That machine will get a Sherline head assembly when I can afford it (i.e. the machines transition from "hobby" to "earning their keep" :-) For Dee and company at Devitt, photos of my Mogliceing are at: http://photos.groups.yahoo.com/group/cad_cam_edm_dro under "Fun with Moglice" Best regards, Randy ------- Date: Thu, 8 Aug 2002 07:40:37 -0400 From: "Ron Ginger" Subject: Backlash is BAD! All this long discussion of Z axis backlash and compensation just re-inforces my view that backlash is bad and must be eliminated, not compensated for in software. In the suggestion of doing a Z-axis 1 step up to get the backlash compensation neglects the small amount of time it takes for the comp move to occur. When you send the mill down to its desired position it may immediately grab and pull down to the limit of the backlash. Your next move up will then pull the tool back up, but you have already made the divot in your work, so its too late. In a manual case on a mill as small as a Sherline one can press down on the head while turning the crank and feel the backlash. Backlash must be eliminated. There is no other way to get good work. A spring loaded backlash device may work IF the spring load is great enough to cover all loads. Thats a big IF and it adds a lot of wear. ron ginger ------- Date: Thu, 08 Aug 2002 08:34:11 -0400 From: "Dan Statman" Subject: Re: Backlash is BAD! Ron, Sure you want to eliminate as much backlash as possible, but that is not always possible or economically feasible. Plenty of very high quality parts have been made with machines containing backlash. In your example it certainly is possible for the tool to grab or the headstock to settle in the 1/4 second between z-axis moves to take up the backlash. But in practice it most likely will not happen, and it is certainly a heck of a lot easier and cheaper to write some code for backlash compensation (or download TurboCNC and try it out)and see if this cures your problems. Sometimes perfect solutions for every posssible range of conditions are not required, and quality parts can be made immediately with the current state of a machine if you compensate for its limitations. It could take hundreds of dollars and weeks of time to remove the backlash, and it still won't be perfect. As always, this is just one man's opinion. Dan. ------- Date: Thu, 8 Aug 2002 07:10:15 -0700 From: "Yasmiin" Subject: RE: Backlash is BAD! Perhaps I am missing something but all machines have back lash, even the best ball screws have it. Compensation for back lash exists in all CNC machine tool controls. This is usually a configuration parameter and the inclusion of compensation requires nothing but the entry of a parameter. Of course most machine tools are using some sort of absolute positioning ( glass scales / DRO ) also. Therefore, I don't understand the drive for elimination of back lash. The back lash in the lead screws of my Wade 94 ( Super Slide ) is .005. Wade has told me that redoing the lead screws would have no real benefit and cost more than its worth. I mention Wade because it advertises tolerances and repeatability in millionths. Yes this is a manual machine but I still don't see the issue. It should be possible to move the lead screw to compensate for backlash without moving the slide. If you can't then perhaps the problem exists in the adjustment of the slides? Yasmiin ------- Date: Thu, 8 Aug 2002 08:34:27 -0700 From: "Marcus & Eva" Subject: Re: Backlash is BAD! Hi All: I think a fundamental point has been overlooked in our discussion of how to deal with backlash in Z on a bedmill. The critical "must haves" in a system that has backlash, is sufficient headstock weight to keep the head down as far as the screw will allow. This can be exacerbated or helped by the condition of the Z axis ways. We have all been assuming that the normal condition is that the screw actually DRIVES the head down, and that the head would sit passively in position wherever it was placed in Z, even if the screw was missing. I don't believe this to be the most desirable condition with respect to the backlash. As I see it, the way to improve the repeatability of the Z axis most reliably is to INCREASE the weight acting on the Z axis screw and REDUCE the friction between the ways and the head. This is how all large bedmills (mills with moving heads) operate. The ratio between the head mass and the coefficient of friction is very high on these machines so the mass of the head holds the cutter in the cut. (They are HEAVY and have relatively LOW friction). On these machines, the screw merely acts like an adjustable shelf that the head sits on. On a teeny machine like the Sherline, we have less of this advantage to help us. So, the way to improve performance with respect to Z axis repeatability is to reduce the coefficient of friction between head and ways. The best ways I can think of to do this are as follows: First, pay very close attention to the condition of the ways in Z and improve them with lapping or grinding if needed. Second, consider applying a low friction material like Moglice or Turcite to all the sliding surfaces. Third, keep the gib adjustments appropriate and the Z axis ways well lubed at all times. Fourth, as Alan has done, tune the leadscrew position so it doesn't contribute to stick-slip of the head. In addition, you can improve the Z axis performance by ADDING weight to the head. It should be properly balanced to reduce the cantilevered load on the ways that the wildly off-balance stock head produces. The extra weight can be easily compensated by beefing up the stepper. If the nut notices the difference, a longer nut more securely mounted is in order, perhaps accompanied by diamond lapping the screw to make it smooth enough not to chew up the nut so fast. Pressure lube in the screw and on the ways is good too and not difficult to rig up. All of the ingenious mechanisms to reduce the weight on the head with counterforce springs etc, are counterproductive unless the backlash can be reduced to negligible amounts and maintained that way indefinitely. Only a preloaded ballscrew has a hope of meeting these conditions. So, my advice to all who are wrestling with this problem: Pay close attention to the condition of your ways and make them the best they can be. Remove any weight reducing devices you may have on your Z axis and consider adding counterbalancing weight instead. Cheers Marcus ------- Date: Fri, 09 Aug 2002 08:38:25 +1000 From: "Charlie Lear" Subject: RE: Re: Backlash is BAD! ball screws Moglice, turcite, counterbalances, shifting the motor, ballscrews... I totally agree that we should do everything we can to make sure the sliding friction is reduced to a minimum. For the vast majority of us that will be oiling the ways and adjusting the gib (after taking off the gib's high spots by using very fine emery paper and a flat surface). I have never - touch wood - had the head drop on me during a cut. You take the backlash and stick/slip out by deliberately advancing the head further down than it needs to go, then bringing it back UP to the starting position for the cut. For me that normally means a full turn of the feedscrew with my other hand resting on the headstock, then bring it back on the dial to where it should be. (My mill doesn't have the lock nut, so I have to carefully watch the z axis doesn't start creeping during a cut. Any sign of it and I just hold the handwheel in place.) I don't see why it would be any different for CNC, except that it would be easier. Down 0.100, up 0.090 instead of down 0.010. Cheers Charlie Lear, Melbourne, Australia clearx~xxsteammachine.com Hutt Valley Model Engineer Soc. http://steammachine.com/hvmes Eastern Bays Little Blue Penguin Foundation: same site /penguins ------- Date: Thu, 8 Aug 2002 17:08:49 -0700 From: "Marcus" Subject: Re: Backlash is BAD! Hi Randy; You are correct when you suggest that balancing and lowering the loads on the leadscrew will preserve the screw and the nut. >From this perspective, unloading the head is beneficial. However, from the perspective of accuracy in Z, your method is disadvantageous unless you can substantially eliminate Z axis backlash. I spoke purely from the position of how larger bedmills achieve this, and pointed out that the weight of the head is helpful. (In fact, many of these mills use counterweights too, but they do so because some of these heads are outrageously heavy; far more than is needed to hold the head down. The counterweights preserve the screw and also keep the head from sagging.) When you are fully dependent on the lack of backlash to hold your position, you need to maintain it at a higher level of precision than when you make your system backlash independent. .001" is pretty darn good for a non preloaded system, and if you can maintain it over a long period of time, then your solution will be adequate for the vast majority of applications, and has the added benefit of being able to contour in Z for 3D milling. In an ideal world, we'd all have zero backlash systems...my solution is worth considering for those of us who want to improve the accuracy of their mill in Z without having to rely on the condition of the screw so much. I do have a comment regarding those who wrote in, advising backlash compensating upward moves. This is OK if you are hand writing a bit of code now and again, but it'll quickly drive you nuts if you have to do any reasonable amount of programming. None of the post processors I'm aware of, make provision for this, and of course, the move across the backlash needs to be commanded, so it needs an extra line of code for every Z negative move. Since the backlash varies in almost all instances along the length of the screw, it's not an intrinsically reliable method, and, as others have pointed out, it does not permit plunging onto a part very well. You will find that holding Z levels within 0.001 or even 0.002 will be hit or miss with this method. I don't recommend it. Cheers Marcus ------- Date: Thu, 8 Aug 2002 19:41:37 -0700 From: "Marcus & Eva" Subject: Re: Backlash is BAD! Hi Randy: I think a lube fitting right in the center of the nut would be your best bet. I haven't had a Sherline mill for a while now so I can't remember whether there's room for a Zerk type fitting. A plain hole will work too, but does not allow you to pressurize the lube when you pump it in. I'd go with a blind ended slot parallel to the long axis and stopping short a minimum of one turn before each end of the nut. Intersect the cross hole with this (of course) and if you've got the space, put on a Zerk. I like Vactra waylube (I've also got tons of it so it gets used by default, but it works very well too!) With regard to mosquitos and elephants...you are absolutely correct. When I still had my Sherline I recognized the backlash issue immediately (I was doing 3D contouring). My solution was to lap the ways till they were dead nuts parallel. I spent about half a day using a simple split copper lap and 1000 grit Clover compound. I lubed the screw and ways with nothing more than a squirtcan. I didn't add any weight to the head. I ran my programs so all roughing was done with waterline passes, and I constrained the toolpaths for finishing so they'd always start at Z0 and go down. I'd then rapid up, return to the start point of the last pass, stepover, and cut downward in Z again. I was (and still am) using Mastercam and Featuremill to do my programming...both these programs allow good toolpath control. No gouges, nice finishes (for a flimsy stepper rig). This was all in Delrin though...no steel!!! I have no idea of the longevity of my setup though...I got a "real" CNC machine about a month later in a repo sale, and the Sherline was sold to a gentleman who has never cut a part with it (but loves it anyway!!!) Cheers Marcus ------- Date: Sat, 10 Aug 2002 08:21:42 -0400 From: "Ron Ginger" Subject: RE: Moglice Question When I first heard of Moglice I arranged for the sales engnieer of the US supplier to speak at our model engineering club. He came with a slide show of some amazing and HUGE machines repaied with moglice. In fact its the huge machines they want to fix, where the repair cost by other means would be unreasonable. One example was a ball screw abuot 2" dia. The nut shell was bored out and cast with moglice onto the screw. He said in one case some mistake was made and they tried to press out the cured Moglice which took tons of pressure to do. So, I would not be afraid to try it on a big machine, but get the manual and look at some of the repairs to see about proper shape and forming. In the case you describe a small moglice kit (about US$40) would be a cheap experiment. If it failed you could always cut off the moglice and you would be back to where you started and not out much money. ron ginger ------- Date: Sat, 10 Aug 2002 09:20:51 -0700 From: "Yasmiin" Subject: RE: RE: Moglice Question Well I checked out the manual and it looks like it will do the trick. http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/moglice.zip (Thanks Randy) The scraping seems doable as they are talking about 10-12 points per square inch rather than the 40+ that some of the old time books talk about. I do have a set of carbide tipped scrapers. They talk about 50-60% full contact so one is really just putting some dips in a flat surface and I know how to make a flat surface. The under cuts seem to solve my fear of the Moglice peeling and at the same time don't do anything that makes other solutions impossible at a later time. The use of a flat bar as an outside form seems to be their method for filling the hole. So now all I have to do is get the energy and nerve to do it. Yasmiin ------- Date: Sat, 10 Aug 2002 09:52:47 -0700 From: Randy Gordon-Gilmore Subject: RE: Backlash BAD! Balance GOOD! At 06:33 AM 8/10/02 -0400, Jerry wrote: >I'd think that the headstock is already balanced, so your weight ought to >be spindle motor + controller, right? You are right that the spindle-motor-controller weight is what you want to balance laterally, but fore-and-aft you want to balance the whole thing over the ways. The whole head assembly is cantilevered forward from the ways, and gives a wedging effect. The overhung weight produces a moment or torque, so that the bottom of the head is pressing back against the ways while the top of the head is pulling forward on the ways. You want it balanced so that if there was some clearance between the head and the column it would fall straight down rather than tipping forward. Best regards, Randy ------- Date: Sun, 11 Aug 2002 07:08:53 -0000 From: "tauscnc" Subject: Re: Backlash is BAD! ball screws [sherline] Tom Nance wrote: >> Holy smokes, guys! Come on, does anyone besides myself think we have completely gone over the edge on this thread? Look, the Sherline mill is a sweet little machine. But let's face it, it's a *little* machine. It has its limitations and its idiosynchracies but most folks learn what they are, accept them, work around them, and get over it. If you think you need .0001 accuracy, go buy a $10,000 mill. I actually think a great deal of the charm of the Sherline machines is the fact that they don't have all the bells and whistles and the precise accuracy of the giants. It makes one have to think a little harder and plan the cuts a little better. I think that's all part of the fun. Now, I admit, I don't make chips for a living as it sounds like some of you do. If I did I might feel differently about it. I make stuff for the enjoyment of making them. Sure, I've ruined pieces on the mill because of the problems with the z-axis and I wish I didn't have to go thru the pain, but I think that's all part of the game. If there was a simple fix (as I believe we'll learn from Craig when he returns), then I'm all for it. But I think it's crazy to attempt to change the mill into something it was never intended to be. Years ago, I bought the DRO Sherline offers. Before I bought it, I looked thru the instructions on their web site and read Joe Martin's feelings about the DRO. He basically said (paraphasing) "if you think you just HAVE to have this thing, I'll be happy to sell it to you, but you'll really be happier using the hand wheels." Well, I figured he was just an idiot, and bought the thing anyway. I mean, after all, what does HE know about the mill? I used the DRO about three months and then gave it away to a guy that felt he just "had to have it" to do anything good. I'm sure in a few months he'll learn and will pass it on to someone else. I think the same sort of thing applies with this thread. Yes, changing the saddle nuts, and redesigning the axis, and adding springs and weights may improve the performance of the mill, but it is also violating the very nature and spirit of a great little machine. Leave the sweet, little thing alone. Recognize its nature and celebrate it. Its not a Bridgeport, don't try to make it one. I need 3 yards of topsoil for my yard. Should I get my cutting torch out and modify my Toyota Camry so I can haul the dirt, or should I get a pickup? We're beginning to sound like Tim "the Toolman" Taylor. There are more posts on dicking with the mill than there are on actually *using* the mill for productive work. Okay, rant over. Now let's hear some really good flaming from you guys. Tom Nance Corpus Christi TX << Hey Tom: Well since you asked :):) I could not disagree more :):)! The type of people that generally buy these machines are the ones that have some internal buring desire since childhood to build, take apart, modify, experiment, and make what they have better in some custom way. What is the purpose of buying this stuff at much $$$ when we could more then likly buy almost the same part somewhere for a few bucks? Now come on, you enjoy taking things apart and seeing how you can make it just "a little better." Yeah, maybe we go overboard sometimes and should step back to see where we are coming from but "customizing" what we have is the name of the game. Its fun to try and figure out how to make something better or work more efficienty in a simplier way. If we just accept everything for the way it is, life would be boring. As for the topsoil, I say you get a BMW M5, you'll look cooler and get around faster :) j/k taus ------- Date: Sun, 11 Aug 2002 11:02:35 -0400 From: "Carol & Jerry Jankura" Subject: RE: Equipment mods, was Re: Backlash is BAD! ball screws Hi, taus: I agree with everything you've written, but would also add that those of us who add CNC to the mix are often involved more in writing and improving the program that runs the machine than we are in actually making parts. What's nice about this equipment is that it is so versatile that all of us can use the same tools (toys????) to achieve our needs, so there's a large enough market to make producing them worthwhile. Aside to Craig - Yes, I've noticed your hat at the N.A.M.E.S. show that reads "Tools, Not Toys" but still consider all of the metalcutting items I have (as well as my ShopSmith, tilting arbor table saw, surface planer, etc....) to be toys. As in "the only difference between the men and the boys is the cost of their toys." ------- Date: Sun, 11 Aug 2002 15:18:30 -0700 From: Randy Gordon-Gilmore Subject: Re: Re: Backlash is BAD! ball screws Scott wrote: >Maybe if Sherline see's that their is enough demand, they will >redesign the machine so ball screws can be added. Also beefing >up the frame so it is more ridged. Sherline (and Mr. Clisby, who originally designed the basic lathe) have really done a fantastic job of making a versatile machine that is well-balanced design wise--no part is much better or much worse than it needs to be, to work in harmony with all the other pieces. People have asked occasionally if this part or that part can be expanded or beefed up or "improved", but the whole thing is in proportion as it is. Folks like myself are just taking the basic machine and specializing it for our own individual purposes. I'd hate for Sherline to make a change that would improve one specific aspect of the machine, but detract from its general versatility. Best regards, Randy (now where are those superconducting magnetic levitating bearings I was going to try fitting to the spindle?!?) :-) -------- Date: Mon, 12 Aug 2002 13:14:25 -0400 From: "Van Lupo" Subject: RE: Re: Backlash is BAD! ball screws Marshall, It was I who suggested that the ball screw could be located along side the slide. I figured that the weight of the motor would balance out the thrust of the screw, besides if you think about it the current factory solution applies the thrust to the side of the saddle. It just happens that the screw is located in the middle of the slide. I am not sure how this would balance anything in the current design. So perhaps placing the ball screw along side the slide and mounting the ball nut in approximately the same location as is the current saddle nut attaches to the saddle you would end up with all the same loads. Only change is the leverage point of the lead screw bearing is now located offset to the end of the slide. Van ------- Date: Mon, 12 Aug 2002 16:37:43 -0400 From: Tom Bank Subject: Endmill Flats -- Catching up on my group digests... Fascinating discussion on the various means by which we can screw up a prized work piece, especially the business of setting the endmill in the holder so it won't (I have a hunch that "can't" is too strong a word) drop down and take more of a bite than desired. It has happened to me, and I am pleased to learn what happened and how to avoid it in the future. Actually, my experience with endmill drop goes back to my first attempt to mill -- a bronze casting that had a lump of excess material that had to be removed. I had a Sears drill press and (believe it or not) a Palmgren X-Y rotary table I picked up from Sears for $150.00 new on sale. I bought an endmill, stuck it in the drill press, locked the casting to the rotary table, and started milling. Sure enough, I soon had a hole through the casting. Fortunately I had put a block of wood under the casting, so the table wasn't ruined. I then went on to buy a Sherline lathe and the Z-column. Found it wasn't big enough in the table. Bought a Delta bench top drill base and column and welded up an elaborate means to put the Sherline Z-column on it (using the rotary table again). Found that it the column would rotate around the vertical pipe of the basic setup, which could be fixed by putting a screw through both the Z-column holder and the Delta column, but I didn't get that far. Instead, I bought a Sherline mill. Like everybody else, I love it. I will say that for those who need a slightly larger mill, that approach might be the answer. I still have the thing and could take pictures if there is interest in the idea. Now, the obvious first mistake I made was to try to mill with a drill press, although there was originally an endmill holder that Sears sold, but I could not find one when I needed it. As the many notes on this list pointed out, the bite of the endmill sucks the bit right out of the holder, and when it is chucked into a three jaw drill chuck there is even less to hold it in place. I guess it has the same effect on a drill, but there you want it to go down, not hold its vertical position and move sideways. It should follow that any sized endmill holder will experience the same problem, regardless of endmill diameter, and that one set screw will have less of a grip on the endmill than a three jaw chuck, making a flat in the side of the endmill a practical necessity. However, the Weldon flat on the 3/8" and up endmills is excessively large on our small equipment. Maybe we should be grinding a very short flat or even a V-groove in the side of our 1/4" and smaller shanked endmills. I have had the problem of endmill movement as have others. I didn't understand it at the time, but that had to be what happened, because I was holding the Z-axis handwheel (before I got the new Z-axis lock nut) and I know it didn't move. I had also dropped down and come back up to eliminate backlash. I think sometime this week I will go downstairs, set up a jig, and cut nice, neat V-grooves in all my little endmills. Regards, and sorry for the long post, Tom Bank ------- Date: Mon, 12 Aug 2002 19:16:22 -0400 From: "Ron Ginger" Subject: RE: Backlash is BAD! ball screws >While at this point in time I have no interest in putting ball screws on >my Sherline, someone previously mentioned hanging one off the side of >the Z axis. My thought is that this would create problems becaust of >the thrust not being centered in the middle of the axis. The most common add-on to a Bridgeport mill Z axis is a ball screw off to the side driving the quill through the stub that was meant for the depth stop. So, off center is not impossible. It does require a rigid mount and some careful work, but it will work fine. ron ginger ------- Date: Fri, 16 Aug 2002 11:55:09 -0700 From: Randy Gordon-Gilmore Subject: Re: Questions for Randy At 09:59 AM 8/14/2002 -0400, John wrote: >Now that you have had your counter balance modification and the spindle >motor relocated for several months, have these changes lived up to your >desires / expectations? Are you getting the performance improvements you >expected when you designed these changes? By the way, what length belt do >you use and where did you get it? I'm really happy with the way the Z axis performs. Admittedly, I only did the Moglice retrofit recently and haven't done any contouring since then, but the Z motion has been very smooth and responsive to small increments in Z since I did the prior changes. I can run the Z axis as fast as either X or Y in rapids (but am keeping all three to 20ipm) With the leadscrew nut disconnected I can raise and lower the head with two fingers. The belt is a 6mmx500mm Ametric brand (Made in Germany) that I bought through the local bearing supplier (Applied Engineering Technologies in Fairfield CA). I took in the Sherline belt and told them I wanted the same cross section and about 20" long. Ametric is the brand they carry, but I'm sure it is a standard cross-section. Best regards, Randy ------- Date: Tue, 20 Aug 2002 08:53:12 -0700 From: "Craig Libuse" Subject: Re: Re: Sherline Mill backlash and Fun with Moglice > The top end of the Z ways where the Sherline CNC motor mount bolts on is > not really a finished surface. It has wide tool marks. Alan, This is an old message from August 6th, but I just got back from vacation. All Z-axis columns, both CNC and manual, are now flattened on the top end with a pass of an end mill. Previously only the CNC-ready machines had this additional operation performed, but so many machines are now being converted we decided to do it to all the columns in case a manual one is converted in the future. Craig Libuse Sherline ------- Date: Wed, 21 Aug 2002 18:28:57 -0700 From: Alan Marconett KM6VV Subject: Old "Last Word" Universal Test Indicator (Starrett), CNC backlash Hi to the lists, I've been playing around with adding backlash to a controller program I've been writing, and I THINK it's working! What's not working is my antique "Last Word" indicator (possibly). I have it's 1/16" mount in a collet in the spindle, and the ball on the end of the mount allows the body of the indicator to still shift around a little. Nothing seems to tighten up on the little ball swivel, even if I apply considerable force. The "fingered cap nut" that holds against the ball doesn't seem to hold (threads look fine). Or maybe it's not supposed to? I could understand a little "safety" in allowing it to move if pushed too far. Perhaps it's just too old (yeah, I could use a new one...). I'm also curious how closely the .001" divisions on the indicator should agree with movement? I THINK I've got the pressure square on, that is, the indicator body is perpendicular to the body of the indicator. I could understand if I was at an angle, but I shouldn't be. I don't have any doc's on the indicator, as it was quite old when I bought it used. I do have another "plunger" indicator that is also old and second (third) hand, but it works sluggish, like the oil has dried up in it. I've had it open, but everything looks clean. I suppose it could be in the "spindle" part of it, but I don't think I'm going to take it apart... I'm not sure how "corrected" backlash should look. Oh yeah, I know what backlash looks like, you go one direction for a while, then when you reverse, it takes nn steps before the axis starts to move back. Then the axis moves for each step that is issued to it. Fine. But what happens (what is observable) with backlash correction? At the change in direction, the controller "provides" the steps need to get the axis moving again. Not sure what this looks like on the hardware. I suppose the axis "delays" while the backlash is taken up, then moves the required distance. If I turn backlash off, I "loose" distance compared to when it is enabled (when moving back and forth between two points, my test case). So I believe it is working. However I don't have a good way to "know", because I don't read the full .010" move I commanded on the indicator. Do I need a setup with two indicators, spaced a specified distance apart? would that help? This backlash now has me captivated, since I ran into the "casting problem" a week or two ago. Alan KM6VV P.S. Oh yes, the new boxbed casting and some "sundries" (taps and dies, and some steam pipe) came in from Stuart. £86+, more then the cost of the 10V steam engine! ------- Date: Mon, 9 Sep 2002 21:24:53 -0400 From: "Carol & Jerry Jankura" Subject: Z-Axis Preload Nut Folks: Yesterday, I decided to do a little manual milling with my CNC Sherline Model 2000. While moving the Z-Axis by turning the handwheel mounted on the rear motor shaft, I noted what appeared to be excessive backlash. On investigating, I found that the preload nut was quite loose. This was not how I had set up the machine, so my questions: 1. Any ideas what caused the preload nut to unscrew? 2. Any ideas short of loctite or something similar to prevent this from happening? Carol & Jerry Jankura Strongsville, Ohio ------- Date: Mon, 09 Sep 2002 18:35:15 -0700 From: Alan Marconett KM6VV Subject: Re: Z-Axis Preload Nut Hi Jerry, I believe Sherline DOES Loctite the Z axis preload nut, and the coupler into the bearings. Alan KM6VV ------- Date: Sun, 17 Nov 2002 22:38:27 -0000 From: "smittys8002000" Subject: Positive "Z" axis stop I have read in the past that some have had trouble with the Z axis "Falling" or creeping down from a set point. I too had the same problem, and finally decided to fix it. It is a crude fix, but I no longer have any trouble with the Z axis. All I did was install a 3/4" 90 DEG bar with a 1/4 20 threaded rod through the bar. I made it long enough to be able to adjust it for different heights. I bolted it to the top of the 2 bolts that hold the mill column to the base block. I will post a picture of it later tonight. Smitty ------- [NOTE TO FILE: There is a series of pictures and instructions on the Yahoo Sherline group site in the photos section that shows a clever set of clamps/mods to deal with backlash on all 3 mill axes. Simple and relatively bulletproof. Could apply equally well to Taig lathes and mills as well as Sherline lathes and mills and similar small machines by other makers.] ------- Date: Wed, 20 Nov 2002 12:35:54 -0800 From: Dave Martindale Subject: Locking Z-axis [FROM THE TAIG GROUP] It seems to me that the Z axis is a different case than X and Y. All three axes have some mechanical backlash, but only Z has gravity acting on it. Suppose you are milling in the X direction. The X axis is feeding the cutter into the work, so you took up all the backlash in that direction before the cutter reached the work. If you are doing conventional milling, cutting forces are pushing the work against the direction of feed, so the backlash will remain taken up. (If you're climb milling, the cutter could pull the work into the cutter by suddenly moving the table to the other end of the X backlash, which is why climb milling is a potential problem). The Y axis isn't doing anything during this, but you had to initially feed the cutter into the work in Y, and this took up the backlash in Y. Nothing is going to change this during cutting. But in Z, things aren't so clear. If the last head motion you made was to raise the head, the backlash will automatically be taken up in the downwards direction, so the head can't lower any further, and gravity will hold it there. If the last head motion was downwards, the head will be at the top of the range of backlash if the sliding friction is greater than gravity, and at the bottom if gravity was stronger. If the head is still at the top end of backlash when the cutter contacts the work, cutting forces and gravity can suddenly overpower friction and pull the head down by the amount of the backlash. This can make a mess. To avoid this, you either need to always lower the head too far and then raise it back to where you want (can be a problem when cutting pockets), or supply enough downward force (extra weight, springs) that the head is always at the bottom of the backlash, or lock the head. The above assumes that cutting forces tend to pull the tool down. If you have a left-hand spiral tool, cutting forces would provide up force on the tool, which is the opposite problem. Dave ------- Date: Thu, 21 Nov 2002 03:35:57 -0000 From: "Robin S." Subject: Re: Locking Z axis [taigtools] "jumbo75007" wrote: > Thanks Nick for your info. > Thank you Dave for your explanation about the direction > of backlash/last movement vs unintended movement of the > axes during machining. I understand about backlash, but I did not > connect it to the walking of the axes. This may be old hat to some, > but this is very enlighting to me! This also explains why I > have not had a problem with the y axis walking on me. > BTW, until I have a much better handle on machining, > I will continue to lock the Z axis. Backlash is not the only cause of wandering slides. If you're running the tool reasonably hard, the vibration of the flutes impacting the work will creep the screws along. On a side note, one must also be aware of the cutter moving around. If something isn't right (or even if it is) a cutter can slide around in a collet and move (normally) up into the collet. This is especially true when plunging. It's very important to have the drawbar tight and there should never be any oil on the shank or collet when the cutter is installed (not to mention oil can and certainly does hold particles of grit and swarf which can mess up the clamping). I noticed Dave mentioned climb milling as being a potential problem. It can be a _serious_ problem. If you're machining a gummy material like aluminum, the cutter can grab the work and pull slide (due to backlash). This can result in the park coming out of the vice and possibly being flung at the operator. The only time it's alright to conventional mill on a manual machine is when you're reversing feed to get a better surface finish (usually necessary on aluminum) without changing the axial/radial depth of cut. Regards, Robin ------- Date: Tue, 24 Dec 2002 23:46:40 -0000 From: "santorelli333 " Subject: Ballbearing trust-plates replacement!!!!!!!!!!!!!!!!! Since my moglice just arrived from Germany (the teflon type) I am planing to improve my Sherline where it needs it the most and replace the feed (brass) nuts and to mount the feed-screws for X & Y axis in omega-housed ball-bearings The x axis bearing will be mounted upside down on a mounting plate attached to the table using T-nuts(bolts actually) and the y axis will be mounted on a piece of alu bolted to the front of the mill (have to drill and tap holes) The additional bonus of the bearings combined with the moglice is that I will gain close to an inch of Y travel and a more than that in the X axis Does anybody here now about anybody who has done the ball-bearing part before (hardships success problems links to site etc.)? San ------- Date: Tue, 24 Dec 2002 17:39:01 -0800 From: "Scott A. Stephens" Subject: Re: Ballbearing trust-plates replacement!!!!!!!!!!!!!!!!! There are pictures in the CAD_CAM_EDM photo section of it being done. You can find out who the author is and write him about it. ------- Date: Sat, 29 Mar 2003 13:07:16 -0000 From: "oodnadata" Subject: z-axis backlash I've been attempting to adjust the Z axis backlash on my mill and the best I've managed is .005-.007 ". Has anyone been able to get better results without any modifications ? TIA ------- Date: Sat, 29 Mar 2003 15:23:22 -0000 From: "cxavier2002" Subject: Re: z-axis backlash Mill Z-axis modification posted on 07/20/2000 by alenz I just finished the modifications 2 days ago and seems to work well after some adjustment of the screw nut. You can look it up at "posted files" in this group. Cheers, Xavier ------- Date: Wed, 30 Apr 2003 10:06:12 -0500 From: "Nance, Tom" Subject: RE: Lost steps in Z axis From: smitty8002000 [SmittysSpeedWorksx~xxattbi.com] >>>Got my CNC mill working, have been enjoying making parts again. But I do seem to be losing steps in "Z" when drilling. I have slowed that axis down, almost to a crawl, but still miss a few steps. I am drilling Titanium. I have 250 oz steppers on all 3 axis, should I get a larger spetter for the Z axis? Thanks for any advice you may offer, Smitty <<< Hi Smitty, What could be happening is an effect of backlash. Consider this scenario: When the mill is in the raised position, the head is resting on the "bottom" of the screw threads. It remains there as it is lowered riding on the bottom of the threads. The weight of the head keeps it pushed down against the threads. Then the drill bit makes contact with the work and the situation changes. The bit may be reluctant to enter the work so the screw keeps turning but the head doesn't move. When the screw turns enough for the "top" of the threads to make contact with the nut, then the bit is driven into the work. But during that time when the screw is taking up the slack (or backlash) between the nut and the screw, it appears that you are dropping steps. You really aren't it's just a weird form of backlash that needs to be taken into account. Tom Nance ------- Date: Wed, 30 Apr 2003 12:32:25 -0700 From: "smitty" Subject: Re: Lost steps in Z axis Tom, I thought of that as well, but I am also milling slots into these shafts that I am making, and Z will always return to 0.00. But once the drilling is done, Z is no longer at zero. Smitty ------- Date: Thu, 01 May 2003 05:03:06 -0000 From: "smitty8002000" Subject: Lost steps in Z Since the sherline CNC mounts come with a new leadscrew, is the Z axis leadscrew the same pitch as the other screws? I was running more parts today, and noticed the the Z axis would not come up to the correct spot after each peck drill, it would go past the zero mark each time, and compound the error with each pass. Once the cycle is finished, the error in resetting "Z" to zero is the same distance from part to part. So that brought me to thinking that the "Z" axis has a different pitch then the other two. Can someone shed some light on this? Smitty ------- Date: Wed, 30 Apr 2003 22:10:10 -0700 From: "Dave Hylands" Subject: RE: Lost steps in Z Hi Smitty, My mill has CNC mounts and the Z axis is the same as the others. Even if it were different, If you move it forward N revolutions and then move it backward N revolutions, it should wind up in the same spot (minus the backlash). I'd also check your stepper motor couplers. If the sets screws aren't tight, there could be slippage there, Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Thu, 1 May 2003 09:24:30 -0700 From: "Carol & Jerry Jankura" Subject: RE: Lost steps in Z Sherline uses the same leadscrew pitch for both their CNC and non CNC versions. Note that while you replaced the leadscrew, you did NOT replace the saddle nut. The difference between the two leadscrews is in the end that the motor mounts to. The CNC version uses a set of preloaded bearings to minimize the backlash. Carol & Jerry Jankura Strongsville, Ohio ------- Date: Thu, 1 May 2003 22:41:22 +0200 From: "Isak Levinson" Subject: Re: Lost steps in Z axis Which program are you using? I had the same problem with EMC. It took me a while to figure out that some lines in the ini files caused it. -------- Date: Thu, 1 May 2003 21:32:32 -0400 From: "Marshall Pharoah" Subject: RE: Lost steps in Z When it moves down to peck, does the stepper slip, ie. Not enough torque? This could also provide the symptoms you see. Marshall ------- Date: Thu, 01 May 2003 18:56:36 -0700 From: Alan Marconett KM6VV Subject: Re: Lost steps in Z Hi Smitty, Marshall, Just another thought, if the drill is clogging up, and you are at max depth of the drill bit, you can loose steps due to the excessive pressure required in these circumstances. I had it happen! Fix was to use a longer bit. A dull or miss sharpened bit might do similar. Alan KM6VV ------- Date: Thu, 01 May 2003 20:13:10 -0700 From: "todd smith" Subject: RE: Lost steps in Z Actually, the Z axis was missing steps when in rapid retract. So I just slowed the whole axis down, and all is normal now. Thanks to those who helped out! Smitty ------- From: "Al Lenz" Date: Wed Sep 3, 2003 1:53 pm Subject: RE: [sherline] Al Lenz Mill Z axis mod > I saw in the files section Al's very neat looking Z Axis mod. > My 5400 mill is about to get the CNC treatment (I bought the > Sherline CNC conversion kit so now I'm committed!). > My question is, will the CNC conversion kit still fit if I > do the Al Lenz mod first? Has anybody done both? > Perhaps Al is listening and he can advise? -Tim Tim: You don't need it. The Sherline stepper mounts come with a pair of preloaded bearings in all three axis. In fact the existing z-axis lead screw and upper mount gets replaced in its entirety. BTW their bearing configuration is surprisingly similar to mine. Al ------- From: "Charles Hixon" Date: Wed Sep 3, 2003 2:53 pm Subject: Re: Al Lenz Mill Z axis mod Based on the nature of Tim's question and Al's photos, I was confused as to what Al actually modified. I thought Al addressed the z saddle nut backlash whereas Al's response indicates this is a leadscrew preload bearing assembly. So, to add to Al's response Tim: you will still be fighting a 0.010" or more backlash at the saddle nut with an NC mill conversion. So far, I've found two folks who address this: Rich Dean and Tauseef Tahir. Sooner or later you will be considering their backlash modifications. Charles Hixon ------- From: "JERRY G" Date: Wed Sep 3, 2003 7:20 pm Subject: Re: [sherline] Re: Al Lenz Mill Z axis mod Is it possible to program in the .010" backlash to counteract the loss? Regards, Jerry G ------- From: "John Guenther" Date: Wed Sep 3, 2003 8:17 pm Subject: RE: [sherline] Re: Al Lenz Mill Z axis mod Yes, but it seems better to me to find the source and fix it. I believe if you adjust your mill according to the Sherline directions you will not have more than .003 backlash. Try making sure your mill is properly adjusted and lubed and I am sure you will be happy. I have .003 or less on all axes on my 5400 mill and that works fine for me. John Guenther Sterling, Virginia 'Ye Olde Pen Maker' ------- From: "JERRY G" Date: Thu Sep 4, 2003 1:13 am Subject: Re: [sherline] Re: Al Lenz Mill Z axis mod John, I am with you. I have taken up on the counternut for the lead screws and have very little backlash. And I go past and come back to take up the backlash anyway. Regards, Jerry G Fresh Meadows, New York "Ye Olde Toolmaker" :) ------- From: "Carol & Jerry Jankura" Date: Wed Sep 3, 2003 10:50 pm Subject: RE: [sherline] Re: Al Lenz Mill Z axis mod > Is it possible to program in the .010" backlash to counteract the > loss? Regards, Jerry G Hi, Jerry: TurboCNC, and many others, allow you to program a value for backlash for each of your axes. Whenever you change direction of a given axis, the motor will first rotate some calculated number of steps to account for this backlash. So, YES, several G-Code interpreters allow you to account for backlash. However, that's not the end of the story. Backlash in your system is caused by "slop" somewhere in your mechanics. Accounting for backlash in your software doesn't eliminate it, it only attempts to put the leadscrew so it starts moving the carriage (or whatever) when it starts making a controlled move. Your tool, however, is free to push or pull the carriage for anything between zero and the actual backlash. So it's possible that the machine can still put the cutter at a place other than where you'd want it. Jerry J ------- From: "timxdunn" Date: Fri Sep 5, 2003 12:34 pm Subject: Re: Al Lenz Mill Z axis mod Thanks to everyone for the responses to my original question. It seems that with the CNC conversion I do not need to makes Al's modification (one project off the list). I was encouraged to hear that the Z Axis backlash can be adjusted to 0.003, my experience so far is that I have about 0.01 to 0.015. Now that I have completed my "taper breaker" that allows me to get tools out of the mill spindle without the aid of a mallet maybe I can adjust the backlash and have it stay good. Tim ------- Date: Thu, 04 Sep 2003 14:48:32 -0000 From: "Charles Hixon" Subject: Re: Al Lenz Mill Z axis mod Jerry, it depends on what you're doing. I notice one responder who claims minimal z-backlash from the saddle screw - and that is possible if (A) the weight of the motor/spindle assembly is great enough to counter the downward milling force (such as downward with a center cutting end mill), and (B) you maintain a vertical spindle orientation. You can *sometimes* program backlash out by (1) readjusting the supplied parameters in the controller software or (2) manually coding - which is straightforward when you are using incremental positioning, or a combination of (1) and (2) You will be less successful in programming backlash when your mill pulls into the work, such as when you are (I) plunging with a center- cutting end mill subject to (A) not being true and (B) being true, and (II) climb milling when the spindle is horizontal. Charles Hixon ------- From: "JERRY G" Date: Thu Sep 4, 2003 12:46 am Subject: Re: [sherline] Re: Al Lenz Mill Z axis mod Jerry, This might bother some people but I think I will stay with the DRO. I'm from the old school because I am old . :) I'll use the way I always accounted for backlash by moving past the right place and then reversing the leadscrew to take it up. Worked for me for fifty years. ! Regards, Jerry G (Glickstein) P.S. I still miss the Bridgeport. ------- Date: Thu, 4 Sep 2003 10:46:53 -0500 From: "Nance, Tom" Subject: Backlash Hi Guys, I don't know squat about CNC nor as much as I should know about a lot of other things. Unfortunately for you guys, I also do not posess the ability to know when lack of knowledge is generally a good condition to keep one's mouth shut. So here are my thoughts. I don't know if it is really a good idea to go to the trouble to program backlash into the drive parameters. I mean, first of all, how do you know that you have the right value? It is a very difficult thing to measure accurately and reliably. And secondly, it's going to change on you without notice. So it seems it is a dicey proposition to start with, and yet it is so easy to avoid backlash in the first place. Offhand, I would say the solution is the design of toolpaths that negate the effects of backlash. I don't know what the backlash on my mill is and I really don't worry about it. I mill very precise parts everyday and never think twice about whether the mill head is really where I think it is. I have no doubt that most experienced machinists feel the same way. If you follow three simple rules, you will never have to give backlash another thought. 1). Your machine has backlash. Get over it but don't let it bite you. 2) Never reverse the direction of an axis an odd number of times. 3) Make your first movement after finding a reference point (edge, hole, etc) in the same direction of the last movement when approaching the reference. Now after saying all that, I will admit that z-axis backlash is a different kind of critter that is most difficult to deal with as Charles points out below. Standard rules do not apply. There are other problems in the z-axis as well. It just makes my day when I act like an idiot and take too big of a cut on work that isn't as well clamped in the vise as I think it is and the work is pulled upward in the vise. On the other hand, it is quite satisfying to me to know that I have not quite reached the upper limit of the kind of colorful phraseology that is required at moments such as those. Tom Nance Corpus Christi, TX ------- Date: Thu, 4 Sep 2003 12:22:16 -0400 From: "Statman Designs, LLC" Subject: Re: Backlash Hi Tom: You are absolutely correct in your assessment, provided you only cut straight line paths, or first order relationships in the X and Y axes. If, on the other hand you are milling a second order functional relationship between the X and Y axis (a parabolic shaped curve), you will invariably encounter a local maximum or minimum in the curve and one axis will have to reverse direction. I have my backlash on my Sherline mills set for a tight 0.001-0.0015", and I use the backlash compensation in TurboCNC. It is simple to measure with a DTI and some test cuts. The DTI will get you in the ballpark, but the cutting load also affects the backlash. I then set the machine to mill a simple sine wave. If the backlash is set too high in the compensation you will see a small step change at the local maxima and minima of the curves. Lower the backlash value and run the sine wave again. This takes only a few trials and you can find the largest value that gives no step on reversal. You can then rotate your sine wave 90 degrees and do the other axis. This works for the X and Y axes, but not the z-axis. All of my milling is 2 1/2 dimensional, so I can always approach the cutting depth from the same direction and backlash compensation is not as critical. I just measure it with a DTI and use the value directly. Daniel J. Statman, Statman Designs www.statmandesigns.com dan.statmanx~xxrennlist.com ------- Date: Thu, 04 Sep 2003 19:47:41 -0000 From: "alenz2002" Subject: Re: Backlash Hi Dan: Could you elaborate on how you handle the Z-axis backlash? Specifically when using tiny cutters and a series of very light cuts. The direction of feed is by necessity from top to bottom. Therein lies the problem with backlash compensation, (you don't want to over travel and then back up). Two methods come to mind, both have faults. One is to set the Z nice and loose to minimize friction, thus letting the weight of the head always keep the cutter at the bottom of the lash. The problem is that now and again it can momentarily hang up and then drop in the middle of the cut. Perhaps a rigorous routine maintenance program could overcome this? Of course this won't work at all for the fellows that have counterbalanced the Z, but that's another subject. Second method would be to tighten up the Z hoping that the cutter will stay at the top of the lash. This might work for the micro size cutters, but a `normal size' will surely grab and pull itself down into the work. Remember guys, we are talking CNC and can't lock the axis. Or is there a third (and correct) method that I'm totally missing? Thanks, Al ------- Date: Thu, 4 Sep 2003 16:16:50 -0400 From: "Statman Designs, LLC" Subject: Re: Re: Backlash I have no problems with the cutter grabbing and pulling into the work piece. I set the gibs for moderate friction, so that the head does not have a tendency to fall to the bottom of the lash after a downward move. Tiny cutters are the only ones that I use 0.010" - 0.040". I also repeat the last milling step with the same final z-value, so if it has settled a bit, then the carved channels will meet correctly when it comes around the cylinder. Remember, my stuff is artistic so exact absolute values are meaningless to me, as long as the carvings are consistent. For my control program I am using TurboCNC which has backlash compensation. It works by taking up the designated backlash when a reversal of direction is called for in a particular axis. This, obviously, is not the way it needs to work on the z-axis. What needs to happen is that when you arrive at your final depth, it should take up the backlash so that the head is sitting on the bottom of the lash zone. Without re- programming TurboCNC (which can be done since it is open source for $20), it is possible to fool the machine into doing this. For my machine with a 20 TPI leadscrew and 200 step/rev motors and 1/8 step microstepping, each step will travel 1/32000 of an inch, or 0.00003125. After you command a move to the proper Z-axis depth, you can command a move to go up by 1 microstep of 0.00003125". This value will not cause a significant movement of the milling head, but it will cause the backlash compensation routine to remove the set amount of backlash. Again, this is only useful for 2 1/2 dimensional milling and cannot be used for 3-D contour milling. For 3-D work you must remove the backlash and not do a software compensation. Daniel J. Statman, Statman Designs www.statmandesigns.com dan.statmanx~xxrennlist.com ------- Date: Thu, 4 Sep 2003 17:46:03 -0400 From: "JERRY G" Subject: Re: Backlash From: Scott A. Stephens Subject: Re: [sherline] Backlash < Advantage with steppers is with the feed back you will not miss a step. Sounds to me like something Fred Astaire would have dug. :) Regards, Jerry G ------- Date: Sun, 29 Feb 2004 17:11:44 -0800 (PST) From: Henry Flymo Subject: Re: Re: unwanted, abrupt Z movement that isn't backlash, but what is it? > After I have lowered the head by turning the Z crank and have come > to a stop, I find that I can get another 0.010" or so of abrupt, > vertical, downward, but unwanted, movement if I just press down on > the head with my thumb or palm of my hand. This can easily happen > inadvertently. However, if I raise the head and then I try pushing > down on the head there is no abrupt, residual downward movement. In > both cases there is always some backlash in the screw itself, of > about 0.006". The abrupt unwanted downward movement occcurs only if > I press down on the head after I have make a downward movement of the > head using the Z-screw. The movement is a sudden jolt downward. What you have is normal for your mill. To fix the problem you'll have to get the CNC upgrade including the nut,lever and ajustment kit from sherline. Or always do the left hand adjustment of the hand wheel to compensate like us old fart's did. I recomend the kit. I have CNC and can't do without it. Check the screws holding the saddle nut to the saddle (and all those in between if you have a 2000). These were loose on my lathe (similar construction) and yielded errors like those you are finding. Tony G ------- Date: Mon, 01 Mar 2004 00:21:17 -0000 From: "rustyturley" Subject: Re: unwanted, abrupt Z movement that isn't backlash, but what is it? In my case, it was the saddle nut on the vertical lead screw of the 5400 mill. I had lived with this and finally got tired of it, so I began tightening the large cap screw and felt it was loose. I rotated the hand wheel alternately to raise then lower the spindle as I slowly tightened the large cap screw. After that, it's been solid and dependable. Rusty Turley ------- NOTE TO FILE: Or the problem is one already discussed above in 2003. ------- Date: Fri, 23 Apr 2004 11:20:46 -0000 From: "Michael" Subject: Backlash adjustment problem Hi all, new to machining equipment so have a stupid question. Just recieved my Sherline lathe/mill package and am having trouble getting rid of backlash on the X-axis (the one that goes left/right) on the mill. I have the model 2000 8 direction mill. There is about a half wheel turn of backlash. I've adjusted the star shaped backlash adjustment all over the place and all I succeed in doing is making the crank wheel stiffer to turn with the same amount of backlash. Any input greatly appreciated. Cheers, Mike ------- Date: Fri, 23 Apr 2004 11:59:52 -0000 From: "c_holm10017" Subject: Re: Backlash adjustment problem Michael, Have you checked the set screw on the hand wheel to see if it has loosened on the shaft? If loose, it will allow rotation that looks like backlash. Chris ------- Date: Fri, 23 Apr 2004 09:51:23 -0400 From: "Jerry Glickstein" Subject: Re: Backlash adjustment problem Mike, that is a lot of backlash, about .025" in a half turn. Make sure the gib is adjusted properly. Loosen the set screw at the rear of the table, push the gib in until the table moves smoothly with no shake or lost motion. Tighten the setscrew. Now, turn the crankwheel to the left to counter the star shaped nut. Loosen the lock for the star shaped nut. Turn it clockwise until you can line up a notch for the locking finger. Take up as much play as you can. You can reduce the backlash down to about .003" if the threaded members are not too worn. Do you know what backlash is? It is always good to know what you are doing and fighting. :) Regards, Jerry G (Glickstein) ------- Date: Fri, 23 Apr 2004 13:52:03 -0000 From: "Michael" Subject: Re: Backlash adjustment problem HI Chris, I had a look at your suggestion but everything is secure. When I turn the hand wheel the threaded rod turns straight away, even if I apply some resistance to the rod. Cheers, Mike ------- Date: Fri, 23 Apr 2004 09:18:28 -0500 From: "Phil Krol" Subject: Re: Re: Backlash adjustment problem Gibs are not for backlash adjustment but rather to adjust for wear on the ways. Those of you with older machines should consider replacing the bronze saddle nut. I found that mine had an unacceptable amount of play but didn't notice it because the wear is so gradual. In milling operations, the installation of a DRO allows for programming actual backlash for all axis so movement in any direction is always the actual reading. The backlash compensation is already allowed for. Phil Krol ------- Date: Fri, 23 Apr 2004 14:26:23 -0000 From: "Michael" Subject: Re: Backlash adjustment problem I had another good look at the equipment and stripped it down and re- assembled everything. I think the hand crank was not in as close as it will go towards the cross-slide and I think that is where the problem was. I've got the backlash down to less than a quarter of a turn of the wheel and will set up now with the DRO etc to work out how much it really is but this amount seems about the same as all the other hand wheels so I'm happy. Thanks for all your suggestions chappies. Cheers, Mike ------- Date: Fri, 23 Apr 2004 11:16:49 -0400 From: "Jerry Glickstein" Subject: Re: Re: Backlash adjustment problem Michael, for future reference, backlash is the actual play between two mating threads, usually a screw and a nut. Regards, Jerry G (Glickstein) P.S. The saddle nut is made of bronze for wear resistance and low cost replacement/maintenance ------- Date: Fri, 23 Apr 2004 17:30:01 -0000 From: "David Wagoner" Subject: Re: Backlash adjustment problem Hi Mike, A quarter of a turn of the handle is still WAY too much for a new machine. My 2000 mill and 4400 lathe were at about 2 to 3 thousands when I first got them. I have modified mine to get less then half a thousands on all of my lathe and mill axes. You seem to be seeing 12 or so. Although backlash is normal in almost any machine, excessive backlash or movment of an axis indicates that something is not assembled correctly and could pose a hazard to you (cutter digging in and snapping etc). You may try grabbing the axis in question and push and pull it. There should not be ANY noticable movement. If there is, than the handwheel may still not be pushed far enough up. Try standing on the handwheel side of the axis and firmly pull the axis toward you. While you have pressure on the screw and handwheel collar (black ring) loosen the handwheel and push it the other direction up against the same collar (black ring). If this does not help, the lead screw could be loose with relation to the saddle nut. Make sure that the saddle nut is tight against the saddle. If not, I can give you instructions to tighten it but it will take longer (it also involves somewhat of a feel to make sure that it is tight AND moving freely). Finally, the "star wheel" may be grossly out of adjustment. These are on the mill (I added them to my lathe also). The star wheel should be screwed just snug enough in to take up any slack that the lead screw and carriage nut may have. But, not too snug to keep the screw from freely turning (another feel thing). I'm sure that I missed something but this covers most of the problems I have encountered in taking the machines apart and putting them together again. Always Be Safe David Q. R. Wagoner ------- Date: Sat, 24 Apr 2004 18:14:53 -0000 From: "David Wagoner" Subject: Re: Backlash adjustment problem > Just a quick one, the more snugly I tighten the "star wheel" the > harder is is for me to turn the crank wheel. which is suggesting to > me that there must be some more slack elsewhere. I have to try your > suggestion to make sure the cranking wheel is in the proper position. > I removed the threaded rod and hand wheel from the bed and rethreaded > it onto the machine without the bed and had a go at pushing/pulling > the threaded rod and there was absoutely no play so I think there is > no slack in the rod or threads buried in the mill. > Hope this explanation makes sense. Mike, Then that does seem to imply that the screw was not fully against the black collar when you adjusted it the first time. As for the star wheel, it is supposed to help take up any wear that has occured in the brass nut inside the mill. After you get the screw and handwheel snug, as I described, then carefully tighten the star wheel until you just feel a very small amount of drag on the screw (Again this is a feel thing that each person is different on). This indicates that the nut inside the mill and the star wheel are forcing the screw against each other to remove any "slop". Then set the "pointer" into the star to hold the star nut in place and tighten it down. Be careful on this also as tightening down the "pointer" can move the star nut on you. The result is that, if done correctly, the table should begin to move in both directions with only the smallest backlash (1-3). Finally, you may want to search back through the older messages as there have been many discussions on how to adjust out the "slop" on the other axis. Best Regards David Q. R. Wagoner ------- Date: Wed, 13 Oct 2004 19:50:55 -0700 From: zephyrusx~xxrickadee.net Subject: Moglice! Some of you are on more than one of the groups to which I'm addressing this (I know I am) and I apologize in advance when you receive more than one copy of this email. I will start by saying that I have retrofitted a Sherline lathe and milling machine using the product but I have no financial interest in Moglice or any of its distributors. Today I got a call from Dee at Devitt Machinery ( http://www.moglice.com ) who wanted to let me know that they have developed a Moglice kit for the hobbyist and small machine rebuilder. It is a direct result of the interest shown by us hobbyists. The kit will retail for US$49.50 and will consist of a 50g of Moglice FL/P, a syringe with which to apply the Moglice, 30ml of liquid separator, 30ml of liquid cleaner, clay with which to make a containment dam (if necessary) and MSDS sheets for all the chemicals. Devitt has had to buy a run of small containers from Germany in which to package the Moglice, and they will be arriving in the next week or so. Apparently that is the pacing item for releasing the kit, and initially they are producing 100 kits. The future of the small kit will depend on how initial sales go. It sounds like a great deal to me. Dee also said that the January/February 2004 issue of "Home Shop Machinist" contained an article called "Repair backlash with Moglice", and Devitt is working on getting permission to reprint the article to go along with the kit. I haven't seen the article, but Dee said it is very well written. Details on the Moglice products are at Devitt Machinery's website, as is their contact information. If any of you are on other small machine email lists, please feel free to forward this message. Best regards, Randy Gordon-Gilmore ProtoTrains Rio Vista, CA, USA http://www.prototrains.com ------- Date: Thu, 14 Oct 2004 09:24:24 -0400 From: "Ron Ginger" Subject: Re: Moglice I did my Sherline, a Grizzley mini-mill and a Prazi mill with moglice. I sold the grizzley mill soon after I got it working- it was such a noisy and crude machine it offended me to have it in the shop. My Sherline has had modest use, but I am using the Prazi now quite regularly. The Moglice has worked fine. I think its an excellent solution for low backlash nuts. I did have some squeeling out of the Prazi screws so I sprayed on some Starret M1 oil. I intend to ask Devit about the proper lube for moglice nuts, but the oil stopped the squeel. I have posted here and have info on my web site about these machines. http://plsntcov.8m.com ron ginger ------- Date: Fri, 15 Oct 2004 10:28:08 -0400 From: "Ron Ginger" Subject: Re:Moglice (or cheaper substitute) From: "Gordon Couger" >I wonder how much stronger Moglice is than epoxy filled with >graphite and bronze or some other metal and lubricant and metal >filler like molybdenum and cast iron or aluminum? >Most epoxies all start with similar resins and I am sure that the >research that they have in their product is quite extensive. For >high heat and heavy loads I would not hesitate to spend the money. >But for light duty use that most of us put on our machines I wonder >if something a lot less expensive would not work as well. I did this. I used the West brand epoxy - which I use for boatbuilding and buy by the gallon. I mixed in graphite powder because I had a can of it on hand, but molybdenum might be better. (Unrelated to this I used the same West/graphite mixture as the glue on the teak cockpit sole of my steamboat. It has survived several years of oil, ash, soot, seawater, sunshine and every other misuse and still looks like the day it was built) I don't recall now whether it was the early Sherline or the Grizzly that I used this mix on, but it has worked just as well for me as the real moglice. I did use the real moglice on the Prazi. My suggestion is to try it- it will cost almost nothing to try, even if you have to go buy a small continer of epoxy, and if it fails you can always drill it out and try again. The only bad problem is not using a good parting agent and getting the leadscrew stuck in the epoxy. That would ruin your day! The Sherline saddle design makes this a very simple job. I used the brass nut and the brass star nut that are in the Sherline to hold the screw in place. I injected the epoxy through the hole normally used by the set screw to hold the brass nut in the center of the saddle. When it had cured I removed the brass nuts. The nice part is if it fails you can just drill out the epoxy and put everything back together in the original way. ron ginger ------- Date: Sat, 16 Oct 2004 09:46:40 -0400 From: "Ron Ginger" Subject: Re: Backlash- was Moglice >I do not use CNC other than the rotary table. The main reason >for this is that it is still not practical for the type of work that >I wish to do. I am not a CNC expert by any means, However it is my >understanding that most if not all programs compensate for backlash. > It is also my understanding that repeatability is more important >than normal backlash with this type of system. If this is the case >I will be happy to demonstrate in my basement that a loose machine >(within limits) with normal backlash will be far more repeatable >than a tight machine. ( Excluding ball screw equipped machines) >If I were to use CNC it is my understanding that the most >efficient accurate system is the closed loop system. I have also >been told that normal backlash with this system is not a problem. >Jerry Kieffer With the right control and software CNC is usefull for ALL work. Some think of it only as a production tool where you are making hundreds of parts. But there are many one-off parts I can make with CNC that would either be impossible or very time consuming by hand. It offers a whole new way of making parts when you can make complex profiles consisting of arc, line segments, filets, etc all in one smooth pass. The most important characteristic is parts where both axis are being moved at the same time -- circles are obvious, but eliptic paths, angles, tapers, etc are all common and simple CNC operations. I doubt either of the Jerrys make many parts by hand when turning both handwheels at once :-) It is these operations that make backlash a problem. Altough software tries to compensate for backlash it is my view that this is useless -- while the program backs up one axis to make the compensation the tool digs a little divot into your work. I will simply state that for CNC operations where both axes move at once backlash must be eliminated, not compensated in software. With backlash you must program parts just like on a manual machine -- always moving only one axis at a time, and defeats the whole usefulness of CNC. The closed loop issue is the single most 'religious' argument in the CNC world. There are thousands (maybe millions) of machines doing parts with simple open loop (step motor) systems. If they are designed correctly and run within their load limits they will NEVER loose steps. Most of the adherents of closed loop are electronic (software) guys who are discovering CNC and can not accept that mechanical things can be designed to work reliabliy without electronic oversight. Closed loop control has no affect on backlash -- if the machine has backlash you will at best make divots in your parts and at worst the backlash will let the table slip, the tool will dig in and break the tool, work, and/or the machine. CNC is a good thing for model makers! ron ginger (I guess I should admit that my model making has been reduced by my machine making as I have learned CNC and got my machines running. But I am now at a point where I can draw a part and just go run the machine to make it. At least on the mill, I haven't started on my lathe yet.) ------- Date: Sat, 16 Oct 2004 11:20:33 -0400 From: "Jerry G" Subject: Re: Re: Backlash- was Moglice Ron, when CNC came in, I was going out, so to speak. But, I have always contended the real advantage of CNC is to program for what you call "one-off parts". The flexibility is the key. Figure out the tool path and off you go. Cool! As far as moving both handwheels at once, many years ago, I had a job to make precise height type (Snap Gages). The upright had to be engraved with lettering and numerals. To identify the tool. I had no pantograph, no stamping machine. So, I went to the book keeping department, borrowed a printing calculator, laid out and figured all the lines needed for the letters and numbers. A forerunner of CNC? :) In the milling machine, a Cincinnati Toolmaster, I set up the uprights. One at a time. With an engraving point of my own making, I "carved" out the letter and numbers. Using both X and Y handwheels at once. When the man hours were totaled up, the Chief engineer called me to his office. He thought he "had me on the carpet". However, when he found out the whole story, by consulting with the purchasing department and seeing quotes to "farm out" the work and then compared it to our cost, not only did he congratulate me on a job well done, but bought me a vernier caliper that I still have! P.S.I filled in the engraving with meltable black and red wax. Very sharp looking! Regards, Jerry G (Glickstein) P.P.S. That job was done in 1962. ------- Date: Sat, 16 Oct 2004 19:15:24 -0000 From: "n2562001" Subject: Re: Backlash- was Moglice Ron, first I will admit that I am not a expert on CNC, So I have to rely on what I am told by those considered experts in the field who I know. There is of course no doubt that without CNC a commercial venture would never survive. While working for a public Utility for the last 35 years part of my responsibility was machine shops since noone else had machine tool experience. Because of this relationship I have excess to the top programers and CNC operators in this area. My comment stating that I do not use CNC because it is not practical for what I do for the most part comes from them. Because time is short in life I am always looking for a faster more efficient way of doing things. If you can design a part within the capabilities of your program and machine there is no doubt CNC may have advanages even for a one off item. However when building a scale model to SCALE you do not have that luxury. I can give many many examples of this on my 1/8 th scale tractor but not to bore everyone I will give only one that kind of stands out. One challenging part was the one piece cast iron carburetor body. The body was constructed of five rather simple machined parts, silver soldered together. No time could have been saved machining any one of these parts on CNC unless you needed more than one of each. From that point the part was bead blasted to remove any excess silver solder and give a one piece cast appearance to the part. At that point the part was measured to make sure all portions were in scale and a small amount of final machining was completed. Total time spent on this part was about four hours. Wondering wether I would have been better off machining it by CNC, took it to one of top shops in the area (who needed a favor)and asked what it would take to do the job. Several days later I was told that it would take several hours to program and seven tool changes, two of witch would need to be specially ground. However they would only be able to do about 85% of the job and had no solution for the other 15%. Other than to say why bother with it. The 15% would not make a difference in the operation however I am not will to take that short cut when building to scale. As soon as someone can demonstrate an advantage for using CNC for what I wish to do I will use it. I feel my opinion is no better than what I can demonstrate, and expect no less from others. Please nail me at a model show and show me I am wrong. I am always willing to learn even though I am bull headed. Jerry Kieffer ------- Date: Sat, 16 Oct 2004 20:22:44 -0000 From: "montanaaardvark" Subject: Re: Backlash / CNC I think it was Jerry G. who said one of my favorite lines, in fact one of the best lines I've seen anywhere (on these machine forums): "Your machine has backlash. Get over it." Hope I remembered that right. Bob W4ATM ------- Date: Sat, 16 Oct 2004 16:58:21 -0400 From: "Jerry G" Subject: Re: Re: Backlash / CNC Bob, I don't know if I was the author of that line. I know I did say that "Backlash is a fact of life." One time, I was taking a test for Machinist for the City of New York. We had to go down to one of the power plants and make a test piece. We were given semi-prepared pieces (by Machinists helpers) that was a round piece of bar stock, faced and centerdrilled on both ends. Stamped with my application number. We also got a drawing. We were assigned a lathe and a milling machine to use. I think the test was about two and a half hours long. The part had a taper, a keyway , and a threaded end to be machined on it. I won't go into the details, indeed it was in 1954 when I took that test, so some of the details are sort of fuzzy in what's left of my mind. I discovered the toolbit furnished had been ground by a Neanderthal. Negative clearances all around. I had to fly to a nearby floor grinder to square that away! But, I do remember setting up for the taper attachment and watching in horror as the carriage moved and the cross slide did not! I yanked the cross slide handle and cranked it rapidly back to clear the piece with the toolbit. Talk about backlash!!! Those two machines had to be the oldest, most worn out in existence...... What an experience.....:) Regards, Jerry G (Glickstein) ------- excessive backlash [sherline] Posted by: "quamit51" timx~xxjolenet.com Date: Thu Dec 21, 2006 8:00 am ((PST)) I have a Sherline mill I converted to cnc with sherline parts. I have excessive backlash(.010 to .015)I have tried to adjust the brass star wheel on the table but do not want to put excessive pressure on it. The book says .003 to .005 is the optimum. What am I doing wrong? Regards Tim ------- Re: excessive backlash Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Thu Dec 21, 2006 8:21 am ((PST)) Hi Tim: The "brass star wheel" is really a counternut. Check all the connections i.e. handwheel set screws, etc. How much mileage is on the lead screw nut? Later, Jerry G (Glickstein) ------- Re: excessive backlash Posted by: "Carol & Jerry Jankura" jerry.jankurax~xxstratos.net Date: Thu Dec 21, 2006 11:27 am ((PST)) Hi, Tim & Jerry G.: Check that the preload nut hasn't come loose. The preload nut is located directly outside of the conic motor mount. Jerry J. ------- Re: excessive backlash Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Thu Dec 21, 2006 12:49 pm ((PST)) Hi Jerry J, Duh! are you talking CNC? What is a "conic motor mount"? I don't know beans about CNC....... Had a bad experience once with it.... (Story available upon request). Hi to Carol... Later, Jerry G ------- Re: excessive backlash Posted by: "Carol & Jerry Jankura" jerry.jankurax~xxstratos.net Date: Thu Dec 21, 2006 1:29 pm ((PST)) Hi, Jerry G: Yes, I'm talking CNC - he started with a Sherline mill and used Sherline parts to convert it to CNC. If you use Sherline's parts, the motor mount looks like a cone with the pointy end cut off and a motor mount on the other end. On the short end (where the pointy part of the cone would normally be), Sherline uses two preloaded bearings to "decouple" the motor from the mill. One end of those bearings is within the cone and has the coupler that the motor shaft mounts to. The other end has the leadscrew and a preload nut. You've got to adjust this nut properly. If it's not adjusted properly, you'll see an increase in backlash which those "star" nuts will not compensate for. Jerry J. Best to you and Henny as you light another candle. ------- Re: excessive backlash Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Thu Dec 21, 2006 1:42 pm ((PST)) Hi Jerry J. Thanks for enlightening (A little Chanukah joke there) me. I have seen photos of the motor as you describe it... Best Regards, Henny and Jerry ------- Re: excessive backlash Posted by: "Alan Wright" alanx~xxyahoo.com Date: Thu Dec 21, 2006 3:32 pm ((PST)) I also had backlash problems after a while on my CNC'ed 5400. The backlash nut could not be adjusted to better than .007-.009, and would not stay there. For a while I was updating backlash comp in Mach3 before every session (at least). This was really annoying due to the difficulty of reaching the x-axis nut. About the time I was fed up with this, the A2Z kit to upgrade to no- backlash screws became available. It is expensive, but a very nice upgrade. Now I get the same performance on my Sherline as on my larger Wabeco mill (which has ballscrews). The backlash is low enough (under .001) to not bother with backlash compensation any more. disclaimer: no connection to A2Z CNC or Kerk Motion. Alan ------- Re: excessive backlash Posted by: "minitool41" minitool41x~xxyahoo.com Date: Fri Dec 22, 2006 10:35 am ((PST)) John Maki wrote: > > Alan, Can you provide additional information on the A2Z kit? I > > looked at their web site and didn't spot an upgrade to reduce > > backlash. Thanks, John Maki "Alan Wright" wrote: > If you go to this link and scroll to the bottom, > wou'll see what I ordered: > http://tinyurl.com/y59ecr Thanks Alan (and all others that replied). I have now found the information, and it looks pretty good. Alan, was this a complex upgrade? How long did it take? Any suggestions regarding the change beyond the instructions provided by A2Z? How long have you been running the new screws? John Maki ------- Re: excessive backlash Posted by: "Alan Wright" alanx~xxyahoo.com Date: Fri Dec 22, 2006 11:31 am ((PST)) I haven't been running the new screws long enough to have much opinion other than that they do get rid of the backlash. The upgrade was rather simple (just remove the existing tables, saddle and screws and mount the new ones) other than one thing: the gibs will not fit the same way as before, since the saddle is changed. So you can expect to either shim the gib if too small, or file down the gib if too large. I had the latter case, but I also made a couple of longer versions of the bent wires that are used to hold the gibs in position (so I did not have to file off quite as much). Alternatively you can also drill new holes for the existing wires, but that seemed harder to me than making longer ones. I filed one gib so much that the geometry changed, but it seems to work so I may or may not try that one again with a new gib. One other thing I should note: since the new saddle is considerably higher than the old one (to make room for fatter screws), and since I was frequently using the full height of the Z-column already, I've found that I need to upgrade to the taller column. Luckily that upgrade is on sale this month so I have it on order. The only other thing that I can think of to mention is that since the new screws move the table 5x as much per turn as the old, it is much quicker to move the table around by hand. So this upgrade is only suitable for CNC, but I don't use the mill manually any more and this speeds up getting things set up. Alan [later message] jerry.jankura wrote: > Could you tell us "what's in the box" in terms of all of the items Let's see if I can remember... there was the saddle, the two lead screws, the lead screw nuts/tensioners, and a couple of motor mounting adapters and a few screws. That's all I recall. The diameter of the screws looks odd. I just put a caliper on one and got .443". Doesn't seem to be a normal size in inch or metric. Here is a copy of the instructions: http://www.swcp.com/~rawright/PrecisionLeadscrewInstructions.pdf Alan ------- Re: excessive backlash Posted by: "The Tabletop Machine Shop" Date: Fri Dec 22, 2006 2:50 pm ((PST)) That's all there is in the kit. The screws are 7/16" in diameter, acme thread, 4TPI (working on getting metric versions). Regards, Peter The Tabletop Machine Shop http://www.TabletopMachineShop.com/ ------- Re: excessive backlash Posted by: "Dave Hylands" dhylandsx~xxgmail.com Date: Thu Dec 21, 2006 9:55 pm ((PST)) Hi Tim: Another place to check is the setscrews which tighten up against the flats on the shafts of the steppers. As they loosen off, the backlash will get worse and worse. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Minor mod, good result [sherline] Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Thu Jan 25, 2007 6:04 am ((PST)) Hello group, Yesterday, after a long, heavy milling run, I noticed my Y axis backlash had increased to about .010". Turned out the Y axis nut had loosened inside the saddle. Decided this was a good time to do my more or less semi-annual complete tear-down, lube, adjust and re-build. Much has been written in earlier threads on various schemes to reduce backlash to the absolute minimum. I've never felt the need to implement any of these, have had no problem keeping backlash under an acceptable .002" with the stock equipment. But, since the axis nut was pretty badly scored, I decided to make new ones. I made them 3/4 inch long vs the stock 3/8 (never did understand why Sherline made them so short) on the theory that longer nuts might have more engagement and less lash. Results were very satisfactory. Both axes run smooth with minimal friction their entire lengths, and backlash is barely measurable with a .001" resolution indicator. This without any help from the backlash nuts. Might be interesting to try making them even longer. (May need gun taps.) I also recall that some have advocated making them from nylon, or Delrin. Note to new hands: you'll need a left-handed 1/4 - 20 tap for the Y Axis, right hand for the X. DC ------- Re: Minor mod, good result Posted by: "Phil Mattison" mattison20x~xxcox.net Date: Thu Jan 25, 2007 7:05 am ((PST)) Hmmm... the same thing happened to me a while back and I tried the same upgrade, but in my case the longer nut produced a lot more friction. But maybe I just tightened the set screw too much. The thin walls of the nut allow it to deform easily and clamp down on the screw. I didn't notice the deformation effect until after I had shortened the nut to the original length, and didn't want to bother making yet another one. I don't much like having the nut deep in the center of the slide. I think it may have expanded some as it wore out because I had a heck of a time getting the damaged one out. I've been thinking about making a new one that mounts on the outside of the slide. Since I'm getting ready to do an overhaul on the mill soon anyway, maybe I'll try it. Might be worth the investment in a left-hand 1/4-20 tap. Phil Mattison http://www.ohmikron.com/ Motors::Drivers::Controllers::Software ------- Re: Minor mod, good result Posted by: "Jerry Jankura" toolzngluex~xxsbcglobal.net Date: Thu Jan 25, 2007 7:42 am ((PST)) David Clark wrote: > ....But, since the axis nut > was pretty badly scored, I decided to make new ones. I made them 3/4 > inch long vs the stock 3/8 (never did understand why Sherline made > them so short) on the theory that longer nuts might have more > engagement and less lash. Results were very satisfactory. Thanks for the information and your results. Please keep us abreast of how the backlash changes as the new nuts wear in. If low backlash continues to hold, you've found an easily implementable fix to the problem. Jerry Jankura Strongsville, Ohio ------- Re: Minor mod, good result Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Thu Jan 25, 2007 8:11 am ((PST)) Hi Phil: Why don't you make your own 1/4"-20 left hand tap? Regards, Jerry ------- Re: Minor mod, good result Posted by: "Bad Brad" atkinonx~xxhotmail.com Date: Thu Jan 25, 2007 3:58 pm ((PST)) David, WOW! I am very impressed that you were able get 0.002" backlash and still be able to use the machine and maintain that amount. I use my mill manually and have never had that little amount of backlash. My mill is 14 years old and has a fair number of hours on it. I will have to try the longer nut thing too. Thanks for the info. FBA ------- Re: Minor mod, good result Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Thu Jan 25, 2007 4:28 pm ((PST)) Hi Brad: If your mill's been used regularly for 14 years, I'd consider replacing the lead screws, axis nuts, and backlash nuts for good measure. Shouldn't cost that much. On a machine of this type I'd regard all of those parts, and the gibs, as consumables. Replace maybe every few 1000 hours machining time depending on how hard you drive your mill. (I figure I run mine on average 10 hours a week, and rarely push it.) Don't want to start another long discussion on backlash, I think we've flogged that horse pretty hard over the past year or so (see the archives). But, for what it's worth, I'd regard .002" backlash on a Sherline as reasonable and acceptable. Any more than that I'd want to do something about. I'm very interested to hear other's views on machine usage and preventive maintainance. DC ------- Re: Minor mod, good result Posted by: "Bad Brad" atkinonx~xxhotmail.com Date: Sun Jan 28, 2007 9:24 pm ((PST)) At the height of my milling activity the mill probably got 20-30 hours per week of use. Even new ('93) I found backlash to be about 0.005" or greater. I have known how to compensate properly and have never had any issues. I have replaced the nuts a few times. Right now I have a very limited amount of time I can devote to machining, I'm raising a Family, and the wear on the screws is something I can deal with. FBA ------- More mods [sherline] Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Fri Jan 26, 2007 11:25 am ((PST)) Hi Group: I dislike interrupting work on projects to modify the equipment, but, now that I'm on a roll, I'm going to try a bunch of stuff I've been thinking about for a while. First is an idea I had a while back during a discussion of whether to mount the mill on a plywood base. Please see photo at [run two lines together as one address]: http://tech.ph.groups.yahoo.com/group/sherline/photos/vi ew/9022?b=13&m=f&o=0 I'm really happy with the way this came out. Seems to me a more clean and open appearance. But the big benefit is that getting the mill up 1+1/8" makes it much easier to access the X axis backlash nut. I can also tip the whole thing back onto the swing arm to get to the X lead screw. More to come. DC ------- NOTE TO FILE: As this "More mods" thread starts with its usefulness in setting backlash, it was left here, but further messages were put into the Sherline Mods General file. ------- Re: Question about Sherline DRO and backlash [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sun Feb 10, 2008 4:52 am ((PST)) "Ray Zdan" wrote: > I hope someone can answer what may seem like a simple question,but I am > still new to machining and need a little help. I have just installed > the Sherline DRO to my Sherline mill and everything went fine except > where it says in the instructions that to set backlash compensation for > each axis that you use a dial indicator to determine how far the > handwheel on each axis rotates before the table starts to move. > My question is how do you do this? Where do you place the indicator > to find this out etc. etc.? I hope that anyone who has installed the > DRO to their machine can help me out. Thanks,------Ray Zdan Good morning Ray: You can place the indicator anywhere that will show table movement. The exact setup will depend somewhat on what type of indicator and mounting hardware you have. Look at the illustrations on this page: http://www.sherline.com/millalin.htm Here the indicator is used to check the alignment of the axes. To check backlash, the setup is the same, but move the axis that is perpendicular to the indicator's lever. For example; to check Y axis backlash, setup the indicator as shown in figure 3 on the above page. Turn the Y axis handwheel to zero the indicator, then zero your DRO. Next, turn the handwheel in the opposite direction and note the amount the DRO changes before the indicator shows any movement. That amount is the backlash. A dial test indicator (DTI) in a universal holder is one of the most important tools in the box. It's used to check backlash, alignment of the axes, alignment of work, and many other tasks. Correct use of the DTI can be difficult to describe in words alone. If you or other members are still unclear on anything, let me know and I'll post some photos. DC ------- Re: Question about Sherline DRO and backlash Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sun Feb 10, 2008 5:34 pm ((PST)) Ray Zdan wrote: > Yes, my indicator is as pictured. A Starrett Last Word with a universal holder ------Ray Z OK, I've posted a file at: http://tech.groups.yahoo.com/group/sherline/files/D.C.Clark/ Sorry about the size. It was a challenge to get both the indicator and handwheel markings in focus at the same time and produce a document with sufficient resolution to read them. Hope this helps some. What it really comes down to is just this: Wiggle the hand wheel back and forth while you watch the indicator. You'll see that the change in the indicator reading lags the movement of the handwheel whenever you reverse direction. That's backlash. After a while you'll get such a feel that you can pretty much tell what your backlash is just by wiggling the handwheel. If you have a CNC machine, jog the axis in .001" increments several times in each direction. Again notice that the indicator lags behind when you change direction. BTW, I don't use backlash compensation; never saw one I really trusted. Coming from the Dark Ages before all these electronic marvels, it's just second nature to me to run out the backlash whenever I make a move. Besides, you should be able to keep your mill adjusted so that backlash is no greater than .002" anyway. This can be safely ignored in most cases. When greater precision is needed to assure correct fit and function, techniques such as match drilling or line boring and the use of assembly fixtures are preferred. DC ------- Re: Question about Sherline DRO and backlash - clarification Posted by: "Alan Haisley" alanhyx~xxroadrunner.com Date: Sun Feb 10, 2008 6:49 pm ((PST)) Ray, One of Dave's important points: "BTW, I don't use backlash compensation; never saw one I really trusted. Coming from the Dark Ages before all these electronic marvels, it's just second nature to me to run out the backlash whenever I make a move." Where he says to "run out the backlash." What this means is to make sure you advance the dial in the same direction each time. If, for example, you first lined up the X axis moving from left to right you want to move from left to right for each following point. If you need to move the opposite direction, move until you are sure that you have gone further than the backlash amount and then come back in your original direction. Alan ------- Clunk [sherline] Posted by: "stupidcaps" leepbyrnex~xxnetscape.net Date: Sat May 17, 2008 8:43 am ((PDT)) Guys, I bought a used 5000, and everything seems to work well-and be solid. Except for the z-axis, when the z has sat (even for a few seconds), and I adjust the hand wheel down, the entire head unit clunks, and falls about 2 thousandths. I have re-adjusted the hand wheel itself, and it has no slop. When smooth cranking, this does not happen at any point on the screw. I am wondering if its possible the thrust bearings are shot, or what this could be. the mill does have the new lever lock for the Z- and it shows no wear. I am stumped... Any ideas? Thank you! ------- Re: Clunk Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sat May 17, 2008 9:05 am ((PDT)) For starters, Check out the nut for the Z axis. Are the screws secured? Is there play when static? I am not in my Model Shop right now... Get back to you later.... Jerry G (Glickstein) ------- Re: Clunk Posted by: "borisb232" j3mr2x~xxborisbrooks.com Date: Sat May 17, 2008 11:34 am ((PDT)) If it's only falling 2 thousandths I'd say this is normal and your Z axis backlash is pretty good. It appears the weight of the head can't overcome the Z axis static friction so the head sticks until the backlash is taken up. Then it unsticks and drops through the 2 thousandths backlash. Sliding friction is always less than static friction so once the head is moving the head weight can overcome the sliding friction and everything moves smoothly. Jim Rickenbacker ------- Re: Clunk Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Sat May 17, 2008 2:06 pm ((PDT)) Stu: It probably is just that your Z axis gib is a little tight. Come to think of it, that may be my problem too. It's that black plastic looking thing on the side of the block that actually slides up and down the steel Z axis piece, the one with the wire "L" sticking into it and the up and down block The block has a set screw that holds the wire at a set point. Loosen the set screw and back the gib off (up) slightly. See if that helps. The game is to loosen the gib up enough that the mill head rides up and down smoothly without loosening it to the point where the block on which the head rides will rock sideways. Regards, Tom Bank P.S.: Off to the shop to see if it works for me! ------- Re: Clunk Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Sat May 17, 2008 2:17 pm ((PDT)) I ASSUMED WRONG!!! The gib is mounted on the other side and to loosen it you nudge it down, not up!!! Sorry, Tom Bank ------- Re: Clunk Posted by: "Alan Haisley" alanhyx~xxroadrunner.com Date: Sun May 18, 2008 8:49 am ((PDT)) Once the lubrication on my z axis dries or wears enough, I have similar problems. My gib is still factory set and does't seem to be an issue in this regard. ------- Re: Clunk Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Thu May 29, 2008 6:03 pm ((PDT)) Being old does have its problems, and yes, memory is one of the big ones. I have continued to think of the "clunk" problem; the gib adjustment didn't cure it for me; so I have come up with three more comments that may help, which have been covered in the past, but for the sake of leepbyrnex~xxnetscape.net, who initiated this discussion back a couple weeks ago, and for any other newer members who have come by the situation, here goes : The reason for the problem with the mill head dropping a couple thou or more after it has been raised and lowered on the Z axis is that the Sherline mill's head was originally designed for the lathe (obviously). This has its good points and its bad points. The biggest bad point is that the motor, which is quite heavy in relation to the rest of the milling head, is mounted over on the right side. This causes a twisting force on the Z axis slide. That's what causes the head to hang up. In effect, it exaggerates the backlash which is found on any other mill or lathe axis by holding the head in the raised position, but when your end mill bites into the work, that overcomes the braking force of the off center weight and draws the head down, taking up the backlash during your cut, and possibly ruining the work piece. [Side note: This downward pull is quite strong and, as has been commented on before, it will also pull on the end mill itself. For that reason when you put an end mill in the 3/8 inch holder you tighten the set screw in the notch; but before you tighten it up securely pull it down so the set screw rests at the top of the notch. Otherwise, the endmill may pull itself down in the holder -- again during the cut -- and ruin your work piece.] Back to the original problem. What can you do about it? The reason I thought about this again is that I was milling last night, had the same problem, and instinctively reached up behind the spinning pulley wheel with my left hand as I turned the Z axis handwheel with my right. Each time I lowered the mill head, I put one finger on the left top corner of the Z axis slide, pressed down enough that it dropped with the screw as I turned the wheel, and then proceeded to mill away. If you are milling a pocket that's the only way to handle the problem, short of taking drastic measures. If you are cutting across from one end, you can take up the backlash by dropping below the level of your cut and then raising the head back up to absorb the backlash. As for the drastic measures, there is a way to "fix" your mill so that the twisting force goes away. If you look through our group's pictures I think you will find several sets depicting modifications that move the motor from its left side location to center it behind the Z axis column. I don't have access to the pictures right now. I have to buy a new computer (mine is eleven years old and the browser on it hasn't been updated by Netscape for the last eight years -- I have to go over to my son's place to see Yahoo! group pictures). I believe that one of the mods depicted was by Tauseef some years ago. The mod obviously requires a longer belt as well as a custom (home) made motor bracket. Any modification to the lathe or mill of that nature will have its benefits and its drawbacks. The drawback in this case is that with that mod in place you can't rotate the milling head on the Z axis. You CAN rotate the Z axis itself, if you have that accessory, but you can't turn the head 90 degrees to do horizontal milling. I bought the horizontal milling accessory, which is expensive, so that's why I haven't done the mod described. Hope this helps (more than my former posts), Tom Bank ------- NOTE TO FILE: There is a tip from Jerry Kieffer about manually removing Z axis backlash in the "Sherline Mill Quirks or Tips" file here. It is included in his message Re: What milling machine [sherline] May 29, 2008. ------- Re: Clunk Posted by: "alenz2002" alenzx~xxbellsouth.net Date: Sun Jun 1, 2008 2:44 am ((PDT)) Tom: In addition to all the good advice that has been offered, I might suggest that removing all possible Z-axis backlash will also prevent the clunk. And will make your mill SO much more plesant to use. I have added two files, 'Z-axiz Bearing Mod' and 'Z-axis Saddle Nut Mod' to the Files section. One is a preloaded bearing and the other is a Delrin insert saddle nut. I would urge anyone to consider these upgrades. Al PS I noticed that the bearing mod file is a duplicate (more or less) of one dated back in 2000 which for some reason I am unable to edit. I think it was moved from another list by a moderator? They are the same except this new one has the drawing saved as a JPG. ------- NOTE TO FILE: The following conversation starts with the subject "Slipping handwheel?" and continues under subject "/metal/Backlash_Adjustment_on_Sherline_Tools.htm". And after the dust settles you will see that it really wasn't what we conventionally think of as a backlash problem. But, this was a great discussion that teaches a good deal about lathe adjustment. [And here you are reading the major messages involved in fairly logical order but stripped of many(!) dozen redundant quotings and requotings. I think my head hurts now ;-] ------- Slipping handwheel? [sherline] Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sat Aug 30, 2008 1:23 pm ((PDT)) All of a sudden, I don't feel at all confident with the handwheel on the lead screw of the lathe bed. It seems normal backlash has moved on up to 1-1/2 turns! Literally, if I have a tool against the face of a workpiece, and rack back one entire turn with the handwheel, it doesn't seem to move. Only about another half turn gets me any feeling of resistance. How do I check this? How do I fix this? ------- Re: Slipping handwheel? Posted by: "Craig Earls" enderw88x~xxgmail.com Date: Sat Aug 30, 2008 3:27 pm ((PDT)) It sounds like you need to set the backlash. Rotate the leadscrew counterclockwise (top of the handwheel coming towards you" until you know the cross slide is moving to the right. Loosen the handwheel set screw and push the hand wheel firmly into the lathe bed, then tighten up the set screw. This should remove most of the backlash. Craig http://enderw88.wordpress.com ------- [sherline -- a continuation of the "Slipping handwheel?" discussion above] Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sat Aug 30, 2008 1:53 pm ((PDT)) Backlash Adjustment on Sherline Tools Charles Fox: Scroll down to "Handwheel Adjustment"... Follow the instructions..... You do not have backlash! ( well, maybe a little; also ) Jerry G (Glickstein) ADJUSTING BACKLASH ON SHERLINE HANDWHEELS What is backlash? Backlash is the amount the handwheel can turn before the slide starts to move when changing directions. This is a fact of life on any machine tool, and on machines of this type it should be about .003" to .005" (.08mm to .12mm). As the leadscrew is rotated, one surface of the thread pushes on the saddle nut to move the saddle. As the direction of rotation is reversed, the thread must move a certain distance in the opposite direction before it contacts the other side of the saddle nut thread and begins moving the saddle in the other direction. Obviously, eliminating backlash would require both sides of the thread to be contacting the nut at the same time. This would cause excessive friction (wear) and make the handwheel very difficult to turn. On more expensive machines, "ball lead screws" are used. They use a series of ball bearings running in a track to drive the carriage; however, they are very expensive to manufacture and one leadscrew could cost more than an entire Sherline machine, so they are not used on small machines. Therefore, backlash is not considered a "fault" with a machine tool but rather is simply a factor that must be kept properly adjusted and accommodated for in your use of the machine. TAKING BACKLASH INTO ACCOUNT WHEN USING YOUR MILL Backlash must be allowed for by feeding in one direction only. Example: You are turning a bar to .600" diameter. The bar now measures .622" which requires a cut of .011" to bring it to a finished diameter of .600". If the user inadvertently turns the handwheel .012" instead of .011", he couldn't reverse the handwheel just .001" to correct the error. The handwheel would have to be reversed for an amount greater than the backlash in the feed screws before resetting the handwheel to its proper position. ADJUSTING FOR EXCESSIVE BACKLASH MILL X and Y axes-Eventually, wear on leadscrew nuts can cause backlash to increase beyond the recommended .003" to .005" setting. Backlash on the "X" and "Y" axes of the mill may be reduced to a minimum by adjustment on the anti-backlash nuts. These brass nuts are located on the handwheel ends of the mill saddle where the leadscrew enters the saddle. The nuts are secured by slotted pan head screws which hold a lock that interlocks with teeth on the backlash nut. There are three versions of the lock. The earliest versions used a pointer to engage the teeth in the backlash nut to keep it from turning. The revised version used a second "gear" type circular lock to engage the backlash nut. This change was made to make the adjustment easier, as the gears remain constantly engaged during adjustment, whereas the pointer must be physically put back into engagement each time it is adjusted. The star gear and backlash nut have about 16 points. Because the mounting hole for the locking gear had to be moved slightly farther from the backlash gear to accommodate its larger size, the new system cannot be retrofitted to the old pointer style lock. The latest version works like the star gear, but the teeth are much finer and look like a knurled finish rather than large points. This further reduces play in the lock and the resultant backlash. This system can be retrofitted to the older style star gear lock but not to the pointer style lock. (An upgrade is available as P/N 5011U/5111U.) To adjust backlash, simply loosen the pan head screw that locks the pointer or star locking gear. Rotate the anti-backlash nut clockwise on the "X" axis and counterclockwise on the "Y" axis until snug. Replace the pointer in position and tighten the pan head screw. (The star gear system eliminates the need to replace the pointer, as it turns with the backlash nut as it is adjusted. With the anti-backlash nuts properly adjusted, the lead screws will turn smoothly and should have no more than the proper .003" to .005" of backlash. TYPES OF BACKLASH ADJUSTMENT SYSTEMS. A new lock now uses a star gear rather than the older style pointer to locate the anti-backlash nut, and a button head socket screw locks it in place. This system is easier to use, but the function is essentially the same. (The hole centers are different, which means the star gear cannot be used to replace the pointer on older models.) The lower drawing shows the older 16-point star gears. The latest system is similar but has more and finer teeth. Mill Z-axis-Backlash on the Z-axis is adjusted by supporting the weight of the headstock with your hand while loosening the handwheel set screw. Lift up on the headstock, index the handwheel 90° to pick up a new spot on the shaft, push the handwheel down tightly against the thrust and retighten the set screw while still pushing the headstock upward with your other hand. If the Z-axis handwheel has the newer design with the support screw in the center, retighten the screw until it just starts to support the weight of the headstock. This will take some of the stress off the handwheel set screw and help it maintain adjustment longer without slipping downward. (Don't overtighten or the handwheel will become hard to turn.) To minimize the effect of Z-axis backlash, always approach your desired setting from the top by coming down rather than lifting the headstock into the desired position. A new adjustable backlash system was developed for the CNC mill in 2004. It is standard now on all CNC mills, but it can be retrofitted to the manual mills as well. See P/N 4017Z/4117Z for a description and link to instructions for its installation and use. HANDWHEEL ADJUSTMENT -- LATHE AND MILL The handwheels are secured to their corresponding leadscrew shafts by a small set screw in the side of the handwheel base. Check them periodically to make sure they have not been loosened by vibration. On the "zero" adjustable handwheels, you must first release the rotating collar by loosening the locking wheel. Then rotate the collar until you can see the set screw through the small hole in the side of the collar and adjust the screw as necessary. If excessive backlash develops at the handwheel and thrust collar junctions, adjust by first loosening the handwheel set screw. Index (rotate) the handwheel so the set screw tightens on a different part of the shaft. (If you don't, it may tend to keep picking up the previous tightening indentation and returning to the same spot.) Push the handwheel in tightly while holding the mill saddle and retighten the handwheel set screw. Lathe handwheel backlash is adjusted in a similar manner. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "William Rutiser" wruyahoo05x~xxcomcast.net Date: Sat Aug 30, 2008 3:10 pm ((PDT)) You can measure the hand-wheel / thrust collar contribution to the total backlash: * Turn the wheel to the left until the table is moving toward the hand-wheel. * Verify that the hand-wheel has been drawn tight against the thrust collar. * Turn the wheel to the right until the table is moving away from the hand-wheel. * Observe or measure the gap between the hand-wheel and the thrust collar. Another possible cause of your backlash is a loose leadscrew nut sliding in the saddle. You may be able to feel the difference between this and backlash between the nut and screw. Take out all the lash in one direction then turn the handwheel to move in the other direction. Try to feel a change in the turning resistance when the nut backlash is taken up and the nut starts to slide. You will need to take the table off the saddle and the saddle off the base to get to the setscrews that hold the nuts. Measure or mark your gib positions so you can reset them. Otherwise you will have to do the gib adjustments from scratch. Good luck, Bill Rutiser ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sat Aug 30, 2008 4:59 pm ((PDT)) Well ... I think it's better. Seems that only about one full turn is needed to start the slide moving in the opposite direction. I'm not at all convinced I've got it under control, though thanks to fiddling, I readjusted the gib of the cross-slide itself, and that runs easier now. I'll go sit in another room and read many of the things you all sent, plus bust my eyeballs on the exploded view of the lathe, to try to understand just a little bit more (who put those locking screws where they are, and why? ). Thanks to all. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sat Aug 30, 2008 6:09 pm ((PDT)) Charles, "A full turn" on the Sherline is .050" ! Not acceptable at all. Should be from .003" to .005" max. Gibs are purely for taking up the play in the slide(s)... Later, Jerry G (Glickstein) ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sat Aug 30, 2008 6:11 pm ((PDT)) Gotta dig deeper then. Thanks ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sat Aug 30, 2008 10:04 pm ((PDT)) It's back to Bill Rutiser's message, part B. I'll take the lathe off the table and search for a solution in its not-so-soft underbelly. But tomorrow, in the light. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "William Rutiser" wruyahoo05x~xxcomcast.net Date: Sun Aug 31, 2008 6:39 am ((PDT)) Charles Fox wrote: > It's back to Bill Rutiser's message, part B. Note that my comments were written thinking ( or maybe not thinking ) that your problem was with a mill and not a lathe. The lathe's leadscrew nut fasteners are more exposed and it may not be necessary to remove the saddle. **Also see David Clark's( a3sigma ) "Crosslide disconnection" posts from the beginning of August. Good luck again, Bill Rutiser ------- **NOTE TO FILE: David Clark's excellent August 2008 posts on the subject of taking apart and cleaning and adjusting our machines [Sherline lathe or Sherline mill -- or other machines for that matter] have the subject "Crosslide disconnection" and can also be read here in the file "Sherline Lathe Quirks or Tips". ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 9:48 am ((PDT)) Found it. Am printing it as I type (whee! multi-tasking!). Will roll up my sleeves and dig into it. I tend to agree it's a very good idea to tear into the machines every year. If for no other reason than to be somewhat conversant with them. If only I didn't forget quite as much in that intervening year. Thanks again, Bill ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "keith harrison" keithrharrisonx~xxtelus.net Date: Sun Aug 31, 2008 9:59 am ((PDT)) Bill: I see there are, and have been lots of these problems with members' leadscrew nut fasteners coming loose. As an inexperienced lathe & mill user, I tend to think (dare I say it), that the trouble may be partly in the design by Sherline?? Keith ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 1:57 pm ((PDT)) I pulled her all apart anyhow, Bill, on the theory that knowing more won't hurt. I did find a couple of problems, and corrected them. Cleaned everything well and relubed. And it didn't help with the initial complaint of too much free play = excessive backlash. I think I know what the real problem is now: a design weakness. To wit: If the set screw on the bed's leadscrew handwheel isn't tightened perfectly, it can slip. And slip and slip, until it's in sorry shape (I can't remove mine to check) and the place it's supposed to grip is torn up, scratched, etc. Unless someone has a really great fix for this, I fear I'll have to replace all $24 (at last count) worth of leadscrew. Which of course means tearing the whole package apart again. Is there anything I can wrap around the business end of the leadscrew that will help the little set screw grasp? Remember, this one has a flat end (to grab a round rod face?). ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Sun Aug 31, 2008 2:19 pm ((PDT)) Hi Charles: My lead screw has a little (aluminium?) end screwed on to the lead-screw where the hand-wheel screws on (concentric to the leadscrew with the screw up the center of the lead screw). I spotted this on converting to CNC :-) Sherline mention in their manual that this bit can become burred by tightening the set screw, so one should pick a fresh area after removing and replacing the hand-wheel. It's also worth cleaning up the burrs when you take it apart for ease of removal and reassembly. The set screw can easily slip and drop into an old set-screw hole if it's tightened overlapping an old indentation. Regards, Greg.P. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 3:11 pm ((PDT)) I just thought what I would do is try to sand or file that whole small area smooth again, and try it that way. I just hope the set screw will extend down far enough to grab well. Thanks, Greg ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 3:28 pm ((PDT)) Nope. Filing and sanding didn't do it. Still slips more than an entire turn before catching again. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sun Aug 31, 2008 3:46 pm ((PDT)) Charles, at this point, get a cup point set screw....Designed to dig in, and you have nothing to lose at this point! ( pun intended ) ... P.S. If you wouldn't mind an Allen Head ( Head ) going around with the leadscrew Hand wheel, use a cap screw. Bigger socket, bigger wrench, greater torque, less slippage. Greg, Charles, Another "fix".... File a flat on the leadscrew where the screw ( set or cap) can drive and not slip. Jerry G (Glickstein) P.S. Just saved you $ 24.00..... ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Sun Aug 31, 2008 4:20 pm ((PDT)) The set screws can be obtained at your local hardware store. The ends come as pointed and cupped. I think, the standard Sherline supplied are cupped. You might consider trying the pointed ones. Also, at the hardware store you can pick out the length of set screw that will grab a bit more thread. Dan ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 6:02 pm ((PDT)) I'll be there Tuesday with notes and venier caliper in hand. Thanks, Dan and JG. Naturally, I have no pointed set screws. Got a bunch of spares (that I've never needed) from Sherline quite a while back, but they're all cupped. Will amuse myself trying to file a flat on the leadscrew to see if that will help. Right now, I have a hogged-out hole in the handwheel -- my fingers just weren't up to screwing a new set screw in from inside the neck of the handwheel. I also have significant down-time. Why does this always happen just before a long weekend? ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sun Aug 31, 2008 6:26 pm ((PDT)) While you're there, (if it's a good hardware store) consider; Knurled cup point screws, or Soft Tip Screws. If the guy looks at you funny when you ask for "pointed", say "cone"....(proper nomenclature is the key). Answer to your last question? "Murphy's Law". Jerry G ( Glickstein) P.S. Also, while you're there, buy 2 T-handled Allen Wrenches. One for the cap screws (5/32") and one for the set screws (3/32"). Save your fingers. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Sun Aug 31, 2008 8:15 pm ((PDT)) Hi Charles: If it slips _more_ than a full turn before catching, then we haven't identified the problem!!!! Is the screw in the end of the leadscrew holding the mounting for the hand-wheel properly tight??? Regards, Greg.P. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sun Aug 31, 2008 9:00 pm ((PDT)) Hi Greg, Give us a clue. What is the part number of the screw you mean? Regards, Jerry G (Glickstein) ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Sun Aug 31, 2008 9:22 pm ((PDT)) Hi Jerry, didn't think you'd ever be short of a clue! ;-) 4000: #40310. 4400: #44211. CNC: #67115. 5000+5400: #40310. 5000CNC+5400CNC+2000: #67115. Regards, Greg.P. ------- Re: Fw: Emailing: Backlash Adjustment on Sherline Tools.htm Posted by: "Charles Fox" cafox513x~xxgte.net Date: Sun Aug 31, 2008 9:49 pm ((PDT)) Greg, I don't know if it's tight. But thanks to your quoting another number from that hideous exploded view. I finally saw that the leadscrew has two extra doodads (don't know the proper terminology -- and won't until I flip the page, lose my place, and strain my eyes to find both numbers in the long, long list of parts) that could be replaced. Aha! he says, with a glimmer of glee. That might be just exactly what I need to check. But it's close enough to 10pm that I'll give it up till the morrow. Again my thanks, guys, for keeping after this. ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 10:16 am ((PDT)) > Are we confusing the mill Z axis lead screw with the lathe lead > screw? My 2000 mill with DRO does have a "locking screw" in the Z > axis hand wheel. Wayne See my previous response, to Jerry's message. One illustration does indeed say there are lathe leadscrews out there with screw-in end pieces. Oops again! The Sherline buying site does indeed have exploded views in PDF, which means you can at least search a part number on the illustration. That certainly helps. But "my" lathe seems to no longer exist. Verrrry interesting . . . ------- Re: Excessive Backlash Posted by: "Wayne Brandon" tiktokx~xxcox.net Date: Mon Sep 1, 2008 10:43 am ((PDT)) On Sep 1, 2008, at 9:49 AM, chieftoolmaker wrote: > Hi Wayne, How are you? Check out message 40131... > Charles asked about his lathe. > Regards, Jerry G (Glickstein) Hi, Jerry: Doing great -- Kinda slow during the summer in Arizona. I should have continued that my 4400 lathe with DRO does not have the screw in the hand-wheel. The hand-wheel is drilled and countersunk for the screw but the lead-screw isn't drilled and tapped. I thought perhaps Greg had looked at the mill instead of the lathe. Wayne ------- Re: Excessive Backlash Posted by: "Wayne Brandon" tiktokx~xxcox.net Date: Mon Sep 1, 2008 11:07 am ((PDT)) Charles: Yes there are lead-crews with screw-in end pieces. I guess I am the one who confused that end piece with the locking screw in the mill which is needed as the weight of the motor and headstock hangs from its hand-wheel. I'll go back to making blank centers for my WW lathe. Once set up, it's good to make extras. I have completed a fist full of brass ones to make a new set of burnishing supports plus extras. My old ones are no longer pretty. Today I will make some steel ones which are handy to have on hand. I used my last steel blank as a holder for a 5-0 center drill -- you only drop that size once. Wayne ------- Re: Excessive Backlash Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Mon Sep 1, 2008 1:07 pm ((PDT)) Okay, let's start over. Set screw, no set screw. Grab the feed screw firmly with your fingers, twist the crank, see if the hand wheel slips. Let us know the results. I too thought I lost a set screw in the lateral feed of my lathe. I called Sherline. They said "no set screw in that hole". They told me why the hole was there but, I can't remember what they said. All I remember is, 'no set screw, don't worry about it." Good enough for me. Dan ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 1:46 pm ((PDT)) No, no, there's definitely a set screw in there. Removed, replaced, in the exploded view, etc. I can even show you the scarring on the scrawny neck of the leadscrew. However, when I grab the leadscrew and turn the handle ... there is no play that I can detect. None while turning, none while trying to move everything in and out. Still, it takes more than a full turn to take up the backlash. ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 2:05 pm ((PDT)) Hi Jerry, I have the 44xxmCNC lathe and the 2010CNC mill plus A2ZCNC XY. 1000 sold. In my hand I have the "Assembly and Instruction Guide". Page 39: 4000 + 4400 exploded view (See leadscrew end detail) Relating to both X and Y leadscrews. Parts Screw #40310 and handwheel mount #40290. Page 40: CNC-ready exploded view. Bottom right corner. Equivalent parts are #67115 and #67105. My concern is that the hand-wheel is turning "more than one complete revolution" before gripping. If the hand-wheel fixing screw is making no contact over most of the 'mounting sleeve' (my term, haven't got the parts list handy) but was gripping at the highest point then the hand- wheel could only turn about 3/4 turn before once again hitting the high point. More than that and either the problem is something else, or there are two problems combining. Greg.P. ------- Re: Excessive Backlash Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Mon Sep 1, 2008 2:06 pm ((PDT)) Charles, I have two copies of the Sherline Assembly and Instruction Guide. (Fourth Edition) There is no Figure 81.....Last page number is 42. Last figure is Number 76 on page number 40. For the Model 2000 Mill Column. Only goes up to Figure 74 on page # 38 that pertains to Sherline Lathe Exploded View and Part Number Listing. On page number 41, there is a list of Part Numbers and Descriptions Lathes and Mills. P/N 40300 is Leadscrew Thrust 40320 is Bearing Washer 40310 does not exist on that list. Furthermore, on page number 180 of The Sherline Accessories Shop Guide, there is a list which ID's P/N 40310 as a 5-40 by 1" Socket Head Cap Screw. Page Number 181 has the same exploded view as on page # 38 in the A & I Guide. Later, Jerry G (Glickstein) P.S. I find no P/N 40310 anywhere on the exploded views. Only on the list on page 180 of the Shop Guide. ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 2:17 pm ((PDT)) Fifth Edition. Nyah, nyah, nyah. Could they have switched to a different system somewhere between edition 4 and 5? ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 2:21 pm ((PDT)) Hi Jerry, mine are "Sixth Edition". #5326. Pg 39. 4000/4400. Pg 40. Ditto CNC. Pg 41. 5000/5400. Pg 42. Ditto CNC. Pg 43. 2000/2100. Pg 44. Ditto CNC. Greg.P. ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 2:15 pm ((PDT)) Hi Wayne, I've been attempting to refer to the ferrule or hand-wheel mount that screws onto the end of the lead-screw. I assume that it was once actually a part of the lead-screw on early lathes and arrived with the advent of CNC and DROs. If that part/mounting screw was loose then the hand-wheel could conceivably turn without effect. It's a possibility and needs to be eliminated. In addition, presuming it/they exist on Charles' lathe he will not need to replace the entire lead-screw, just the worn end/hand- wheel mount. Regards, Greg.P. ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 2:36 pm ((PDT)) Unfortunately, nope, they're not on mine. Well, probably on the Z-axis of the mill ... ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 2:37 pm ((PDT)) Okay, it's starting to look to me like I have the only 4500 Sherline lathe in existence. Offers? ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 2:42 pm ((PDT)) $3.50 NZ plus p&p. (more if it's metric) Greg.P. ------- Re: Excessive Backlash Posted by: "Wayne Brandon" tiktokx~xxcox.net Date: Mon Sep 1, 2008 4:16 pm ((PDT)) Charles, 15 inch bed Sherline Lathes: 4000 = inch 4100 = metric 4500 = inch with zero settable hand wheels 4530 = metric with zero settable hand wheels Both "long bed" lathes come with zero settable hand wheels 4400 = inch 4410 = metric Wayne ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 2:42 pm ((PDT)) And now the bad story ... The tailstock of my machine seemed to have lost a set screw, so I ordered a couple from Sherline. New set screw went in fine, I thought ... until yesterday when I tore everything apart. It seems I had two set screws in the spot for one. With a single one there, and some cleaning and re-tuning of the little brass plate that supplies tension on the inside of the frame rail ... it's very nice indeed. Now all I have to do is figure out how to use the little twisty thing that hangs off the tailstock in front (facing the operator) and seems (!) to tighten the neck. (Before JG beats up on me, I want to understand exactly when and how to use the tailstock grommet against the tailstock spindle. But that took looking up [1] on the exploded view then [2] parts list.) ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 3:15 pm ((PDT)) It's more than one full turn, Dan, before I feel anything in the handwheel. WAIT! Turn wheel, leadscrew moves. Either way. Little delay, backlash, etc. The bloody adjustment under and behind the cross-slide's handwheel, to the leadscrew saddle, is what is really jerking me around. Egad. Guys, I have just driven you nuts working on the wrong end of the stick. Despite gouges and scrapes and the like, when I really bear down on the Allen wrench and lock the setscrew of the leadscrew handwheel, it does indeed turn the leadscrew. It's that fiddly balance between two set screws and one locking (of the cross-slide?) screw that, well, screwed me up. I do apologize and appreciate all your attempts to solve the problem I never correctly identified. Hope you won't remind me of this silliness the next time I have a question. I'll go to my room now. ------- Re: Excessive Backlash Posted by: "keith harrison" keithrharrisonx~xxtelus.net Date: Mon Sep 1, 2008 3:38 pm ((PDT)) Charles: Have you thought of contacting a guy at Sherline by the name of Craig, either by phone or e-mail? I have found he gives quick replies & maybe save you a two hour drive. If you look on Sherline's web site, his e-mail is there somewhere, don't have it handy. He fields technical questions. Keith ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 3:48 pm ((PDT)) Hi Charles: One last bit of advice before I delete "Charles' excessive backlash" from my memory banks: If you find yourself applying more than (say) finger pressure on a Sherline screw/bolt/Allen screw driver then you've probably misdiagnosed the problem and are very likely causing damage to whatever you're tightening against. Regards, Greg.P. ------- Re: Excessive Backlash Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Mon Sep 1, 2008 4:14 pm ((PDT)) Okay, on the cross feed, what is happening?? There are 3 set screws on the saddle. According to the docs, the two outside set screws are set at the factory. That translates into "Dont touch them." If you loosen the center set screw, the saddle will fall away from the lateral feed screw. Now, on the cross feed, it this the part that is giving you trouble??? Dan ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 6:01 pm ((PDT)) All three screws have been loosened and tightened. It seems the two set screws keep the slide in contact with the saddle (um, er, if they're tight enough, that is). The center screw (10-32?) seems to lock the slide tight; loosen it enough, though, and as you say, the saddle will fall away from the leadscrew. I believe I have the two set screws in correct relationship with the slide and saddle -- at least there is no more play, and the slide still moves easily when I turn the handwheel. I just pull that center screw out enough so there's no excessive drag. Does that sound reasonable? ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 6:11 pm ((PDT)) As I understand and do, the two side screws adjust the slide to the saddle and _then_ the center screw then locks it all in place. There shouldn't be any "if they're tight enough" - just turn them freely until the adjustment is correct. If the center screw is too wound in when you're doing the adjustment then you might have to wind the outer two 'tight'. (ouch) You'd effectively be bending the world around your lead-screw (or vice versa :-) doing up the center screw first! Greg.P. ------- Re: Excessive Backlash Posted by: "William Rutiser" wruyahoo05x~xxcomcast.net Date: Mon Sep 1, 2008 6:22 pm ((PDT)) The center screw pulls the saddle nut into contact with the two set screws. The set screws are to be adjusted so the saddle nut is centered on and parallel to the leadscrew. Remove the tailstock and move the saddle all the way to the right. Loosen the center screw, turn the set screws in or out as needed, tighten the center screws. Test that the leadscrew turns smoothly without binding. If it doesn't, repeat. A good starting point would be to have the set screws just touching the saddle nut before tightening the center screw. I have never fiddled with these so the above is what I would do until I learned a better way. Its likely to take a lot of back and forth before you get it right. Why is it this way? It's where the manufacturing tolerances in all the involved parts come together. Good luck, Bill ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 6:47 pm ((PDT)) William and Greg, thanks for your input on how to adjust this tricky little devil. Have you guys considered writing owners manuals for small machine tool makers? ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 7:02 pm ((PDT)) Hi Charles, having read William's post I was thinking his description was worth publishing. The only bit I would add is that the outer screws push only and the centre screw pulls only. I think understanding that is the key to correct adjustment. Greg.P. ------- Re: Excessive Backlash Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Mon Sep 1, 2008 7:17 pm ((PDT)) I know to drop the saddle, you only needed to loosen the center set screw. To be honest, I do not know what will happen if you loosen the two outer set screw. But now, I am totally confused. Just where do you believe you are having excessive backlash, linear feed or cross feed? When you position the DTI how far must you turn the lateral feed hand wheel before the DTI reacts?? Now, do the same for the cross feed. Remember, if you are advancing the feed, first to take the 'slack' out by moving the hand wheel in the opposite direction first, until the DTI reacts. The difference between the points that the DTI reacts is the backlash. Yea, yea, I know, you know all this but, humor me, please. Write down the amount of the back lash and let me know. Not being close to my lathe, I can only guess by saying 1/4 turn of the hand wheel might be about right. Dan ------- Re: Excessive Backlash Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Mon Sep 1, 2008 8:44 pm ((PDT)) Hi Dan: The saddle nut sits on the lead-screw, is pushed towards the lead-screw in a horizontal line across it by the two adjustment screws and pulled away along that same horizontal line by the center-screw. What is holding it longtitudinally to the saddle on the lead-screw (the direction which is felt as major backlash) are the three screws in tension at right angles to that direction. If any of the three screws is loose then major backlash will be evident. (More than one turn of the hand-wheel or over 1 mm so we are informed!) A small amount of that backlash will be taken up with the star wheel after the saddle nut is restrained. The hand-wheel positioning can also create back-lash, independently of the saddle-nut and associated parts. Wear also. Regards, Greg.P. ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 7:35 pm ((PDT)) Ah, Dan, you must have missed my Mea Culpa message. The problem is probably solved -- and it was more of a problem than need be, because I was looking at the wrong part of the cross-slide. I concentrated on the handwheel, and shouldn't have. It's the saddle that links to the cross-slide that was the problem. I took that apart -- and most of everything else -- when someone suggested that I should tear the machine down once a year, clean it, lube it, put it back together and be sure of how everything is tuned. It looks like Greg and Bill have a good lock on what happens to the saddle and its three screws. Check out their most recent messages. ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Mon Sep 1, 2008 7:46 pm ((PDT)) I'll revisit this tomorrow. It seems you're onto something here, Bill. But getting just the right touch with the two set screws is tricky. The saddle keeps wanting to move, until I've snugged the set screws down until it feels too tight. That might have more to the with the gib, though, than the other. I need daylight to dope that out. ------- Re: Excessive Backlash Posted by: "markotime" markotimex~xxshaw.ca Date: Mon Sep 1, 2008 9:32 pm ((PDT)) Has anyone mentioned the use of small, radial thrust roller bearings between the handwheel and the disk? These allow one to tighten up the lash a little bit but allow freer turning of the handwheel. Dunno if Sherline uses these on the CNC versions of their machines, but the early Dan Mauch/ Camtronics conversions did, to good effect. Mark (who saw fit to trim 5000 lines of history from the post...) ------- Re: Excessive Backlash Posted by: "Charles Fox" cafox513x~xxgte.net Date: Tue Sep 2, 2008 11:39 am ((PDT)) (In my best Rosanne Rosanadana:) Oh . . . never mind . . . (Translation:) I think I've got it adjusted correctly now. Saddle seems quite stable under the crossslide, the handwheel turns, all is copacetic. Until the next time I don't understand something. Thanks again for all your help, guys ------- Z-axis Delrin nut [SherlineCNC] Posted by: goranmartic Date: Wed Dec 3, 2008 New pictures posted GM-Z-axis Delrin. Just few words of new upgraded Z-axis delrin nut support. Part is mostly the same as before. Only few changes: -Back part where the setting screws are was made tad 'thicker' so setting screw would not go through delrin nut -Whole where nut is inserted has a small (1mm thick) 'notch' around to prevent delrin nut from sliding down when tools is pressed against part we are working on. -Instead of tiny 1mm delrin holding pin, two larger 4mm diam pins were added. They will prevent delrin nut from sliding up. Those pins have to be made as accuratelly as possible - dril a 4mm hole and than machine pin to match. After inserting pins I run 10mm LH tap again to clear. Conclusion: -Improvement made this assembly quite better than it was. Kontrol of Z-axis feels much better and more accurate. -It is easier to slide motor up and down than before. -I steel feel that an additional backlash compensation is needed (similar as used with brass). ------- Re: [SherlineCNC] Z-axis Delrin nut Posted by: Rich Dean Date: Wed Dec 3, 2008 Goran, yours is almost identical to mine. I used 2 SHCS only to squeeze the cut closed and squeeze the Delrin nut for backlash adjustment. The first nut was black plain Delrin, but extensive operation showed the tendency for it to try to slip out the bottom with sudden reversals to raise the head weight. When I changed to a DelrinAF nut I added a collar at the top. This now prevents the slip out. The main retainer is a screw in the back driven into the nut at a tangent and then the leadscrew removed followed by a few cleanup passes with the tap. I have had excellent service from this nut. No problems at all. RichD ------- Re: Z-axis Delrin nut Posted by: "alenz2002" Date: Thu Dec 4, 2008 I believe your saddle nut is based on my design from the files section. [Look in the files section of the Sherline group.] I welcome your comments and suggested improvements which I would like to consider for a drawing revision. Actually I must admit the drawing is not `as built', but represents a few `improvements' that I made after the prototype. I originally (intentionally) ran the screw thru the edge of the insert, thinking that would secure it. It didn't. Than added the 1/16 pin. The combo worked OK. Then I revised the drawing to clear the screw/insert interference and add the pin. Not a good assumption, since based on your experience, the pin alone apparently isn't enough to hold the insert and the screw still contacts the insert. My bad. Will correct. And by a `notch', I think you are referring to a lip on the bottom ID of the bore that the insert sits in? That would be functionally equivalent to a collar at the top of the insert that Rich referred to? Either choice is an obvious improvement to be included. And I will delete the slit on the drawing for the plastic insert. It looks like the squeeze from the clamping screw is both adequate and better. Comments? As I recall the insert threading was the most trying part. It required a free running fit with no compression. It required tapping with various degrees of compression on the insert to get the right fit. Could you send me a copy of our mods? I would like to update for benefit of newer menbers. al ------- Re: Z-axis Delrin nut Posted by: "goranmartic" Date: Tue Dec 9, 2008 Hi Alen: as I've mentioned at the beginning of the thread I've used your original design, tested it and than improved it a bit. Still I was not completely happy and finally I've added additional Z-axis backlash compensation. I will post few more pictures later. I've just used original (discarded) Z-axis bras nut, cut it in half, removed treads, enlarged hole to 12mm and inserted 'half' delrin nut. This addition helped in further stiffening Z-axis movement (and increased resistance a bit - as expected). With this setup I have 0.15 mm (0.006") backlash. It is not zero and I do not believe you can have it with Delrin on Z-axis. But I believe it will stay 0.15 for long time. I like having Delrin as 'an emergency valve' in case there is some kind of Z force (uuuhhhuuu ...). Better to lose nut and make another one than break something else. I've also installed same Delrin holder on lathe. It is just perfect for that. Backlash IS zero. I will finalized drawings and send it to you so you can publish revised and METRIC (ahaa!) version of. As the drawing is important I would also like to emphasize how important the setup (rig?) is when you make the PART. SPEND 1 HOUR MORE AND BUILD A PROPER HOLDER BEFORE YOU START MILLING!!!! IT WILL SAVE YOU ADDITIONAL 8 HRS OR MORE .... :):):):):) (And just think how long it takes to cut Al block if you do not have a cutting machine) ------- Re: Z-axis Delrin nut Posted by: "Eric" Wed Dec 10, 2008 I just thought I'd give my impression of this Z axis upgrade. I am quite pleased with the results. Positioning is spot on with no real measurable backlash going positive to negative or from negative to positive. No programmed compensation. That's not to say it is rock solid. I can move the head .004 up and down on a 2000 mill. It seems to be more down than up though, which I find odd. Can anyone else verify this is a good number, or should I be looking for a loose part? I also replaced the X and Y nuts with Delrin AF at great results. My compensation on X= 0.0004, and Y=.0001. Thanks to everyone who inspired me to make these changes. Eric ------- Sherline CNC Mill leadscrew backlash and end play help [SherlineCNC] Posted by: "Dan Putman" danx~xxblintzer.com Date: Wed Apr 1, 2009 8:11 am ((PDT)) I have been using my "Sherline packaged CNC" for about 6 months. I have made the usual number goof ups, but at last think I know which end is up. I started chasing a backlash issue as a tune up before my next planned parts run. I had noticed that the backlash in X was about .005". Not bad, but half that much would be better. My previous experience in setting the X backlash was something of a chore since I half to demount the Mill Bed from its bookshelf base. Just to get a feel for how things were going to go I decided to check the Y backlash. To my surprise it measured in at .009". Something was amiss. I backed off the hold down screw on the backlash star wheel and worked the table, leadscrew, and backlash until it felt right. I measured again and still .009". I lock the backlash down tighter until the stepper motor was stalling on moves of .001. The play was still .009". Then it came to me; I grabbed the X table and pulled it towards me. There was movement, and a click. The click was coming from the endplay nut behind the outer leadscrew thrust bearing on the stepper motor housing. By trial and accidental success, I discovered that I could adjust out the end play by snugging up the end play nut against the thrust bearing. With the end play fixed I can now adjust the Y backlash down to about .005". AFAIK Sherline does not mention adjusting the lead screw end play anywhere in their manuals. My questions to those wiser than I. Can I do better than .005 backlash or is that about what I can expect in the real world? I know about the setscrew that holds the coupling nut that couples the lead screw to the saddle. What else should I check to reduce the backlash? N.T. My Y stage moans at about the mid point of its travel on the bed. I have cleaned and lubed everything I can get at (Lead screw, ways, bed. Is this just another life with Sherline thing or can I make this noise go away? Thanks to all. Dan ------- Re: Sherline CNC Mill leadscrew backlash and end play help Posted by: "Phil M" yahoox~xxphilmattison.com Date: Wed Apr 1, 2009 10:01 am ((PDT)) I had a Sherline mill for about 10 years and was never able to get the backlash below about .004 on either axis. Those star nuts are not very snug in their seats, they don't mesh very well, and it is nearly impossible to tighten the holding screw without affecting the adjustment, so you end up leaving in more backlash than you might otherwise. Don't forget that you will have more backlast near the center of travel as the lead screw/nut wears. So you end up setting the backlash at one end of the travel, and settling for whatever you get at the center. Phil Mattison ------- Re: Sherline CNC Mill leadscrew backlash and end play help Posted by: "timgoldstein" timgx~xxktmarketing.com Date: Tue Apr 14, 2009 4:23 pm ((PDT)) Dan: Not the only way to get the lash lower, but a great way to do it is upgrade to our precision leadscrew set and extended travel Z column. We use Kerk Motion precision leadscrews that are far more accurate than stock along with their NTBF anti-lash self compensating nuts. Heck, throw in our extended X and Y and people describe it as an entirely new and more capable machine. Pictures and video at http://www.a2zcnc.com/a2zcncmonstermill.htm While people may tell you they do better than .005" on the stock setup, it is hard to achieve and almost impossible to keep due to the rapid wear of the little brass adjusters when run on CNC. Tim A2Z Corp A2Z CNC division 1530 W Tufts Ave Unit B Englewood CO 80110 720 833-9300 www.A2ZCorp.us/store ------- Re: Sherline CNC Mill leadscrew backlash and end play help Posted by: "dnldkempton" dnldkemptonx~xxyahoo.com Date: Tue Apr 14, 2009 6:55 pm ((PDT)) I will concur with Tim's statements on the Kerk leadscrews, and the anti backlash nuts from A2Z. The single best upgrade to my mill since I started machining. The factory lead screws and adjustments are OK for manual machining, but cannot hold true for long CNC intervals. I cannot say how many times I began a project, just to have something un-adjust, slip, or collide due to the old setup. Now, it runs so smoothly, at nearly double the feed ... all while running the motors at lower RPM's (much more torque). My machine has been running all night, and is still going out in the shed. The performance just can't be matched, and the up side is that I've got so many upgrades to the Sherline, I only need a couple more parts to make another manual mill for a backup. ------- Re: Sherline CNC Mill leadscrew backlash and end play help Posted by: "Chuck" Chuckx~xxWildRice.com Date: Tue Apr 14, 2009 6:57 pm ((PDT)) Another option on backlash: I was trying to mill a PC board for some .65 mm surface mount chips. Backlash was killing me. I measured it to be .004, .005, and .006. After reading a lot of stuff, I decided that trying to adjust that out would just lead to further wear. So I tightened it up a bit, but not much. Then I added the BACKLASH= for each axis to the EMC2 config file (I am not sure if EMC1 has this). With these backlash compensation values set, I then measured the backlash again. Then I tuned the backlash values again measured with the compensation. Using this, I was able to get .0005 repeatable values in direction changes because EMC2 would "take up the slack". I know that this may not help on deeper cuts if the cut moves the board, but EMC will make up for it. Perhaps a combination of the precision lead screws along with emc2's backlash compensation would be the best plan. But if you do not want to upgrade the leadscrews right now (maybe in the future for me, at the moment I have more pressing upgrade requirements), the backlash compensation is a good choice and helps lot! Chuck ------- x axis backlash [sherline] Posted by: "arcmaster3" tomx~xxwade.name Date: Mon Dec 7, 2009 10:51 pm ((PST)) Just discovered that the X axis on my mill has way too much backlash, about 1 1/2 turns of the handwheel. Is the X backlash adjustment under the table, or what? Tom Wade Hope, Indiana ------- Re: x axis backlash Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Tue Dec 8, 2009 12:37 am ((PST)) Hi Tom, One and a half turns? Wow! That is .075" (.050" per turn). Should only be about .003"....Yes, the X backlash adjustment is under the table. Later, Jerry G (Glickstein) ------- Fw: [sherline] x axis backlash Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Tue Dec 8, 2009 1:22 am ((PST)) OK, Tom, Here is the scoop/skinny ! (Marine parlance for news) Under the table at the right hand side of the mill saddle ( P/N 50910 ) Where the lead screw enters the saddle. There are different types depending on the age of your machine. 10/98 seems to be the dividing date. X Back lash nut is P/N 50130 / 51130 for metric Back lash lock is 50150 Now, a little puzzle. On the mill exploded view, the lock screw that goes thru the backlash lock ( P/N 50150 ) is called out as P/N 50211. On the listing, there is no such number. There is a P/N called 50210, which is a 8-32 by 1/4" pan head screw. (Craig, you may want to verify and correct this.) I replaced the pan head with an Allen Cap Screw for a more positive lock. Go to the Sherline Main Page. Click on Help Sheets. Click on the "S" logo for Adjusting backlash. Read up on it. You may also want to check out your hand wheel.... Jerry G (Glickstein) ------- Fw: [sherline] x axis backlash Posted by: "Tom Wade" tomx~xxwade.name Date: Tue Dec 8, 2009 8:37 am ((PST)) I checked the handwheel first, as I had already experienced a loose handwheel before, on a different machine. My quick and dirty method for this is to reach underneath and touch the screw while turning the handwheel. Tom Wade Hope, Indiana ------- Fw: [sherline] x axis backlash Posted by: "Alan" alanhyx~xxroadrunner.com Date: Tue Dec 8, 2009 5:12 pm ((PST)) I just shake the handwheel in and out and look/feel for play. I suppose that one could become so loose that it could revolve on the shaft without the shaft turning but have never seen this. Alan ------- Re: x axis backlash Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Tue Dec 8, 2009 9:14 am ((PST)) Hi Tom: If there's that much backlash, it can't possibly be all between the screw and the nut...anything more than one turn must be due at least in part to something else too. If it was all screw to nut clearance, the thread in the nut would be stripped by definition: in this circumstance, backlash adjustment will not solve the problem. So, you need to look elsewhere too, and the three most common culprits are a nut loose in its mounting, a loose handwheel, and clearance between the thrust faces of the handwheel and the bearing that supports the leadscrew. The easiest test to apply is to lock the offending axis and then turn the handwheel backward while watching the gap between the graduated collar and the thrust collar. If it changes during rotation, the clearance is too big...if it doesn't, the nut is likely loose. A loose handwheel requires looking at the screw while the handwheel is jiggled...if the two move independently of each other, your handwheel is loose. Of course the nut or screw may be worn too, but not enough to result in more than one turn of the handwheel. Cheers Marcus www.implant-mechanix.com ------- Re: x axis backlash Posted by: "Tom Wade" tomx~xxwade.name Date: Wed Dec 9, 2009 8:25 am ((PST)) Actually, on my mill, the handwheel has nothing to do with backlash, as I have the stepper motors installed. The handwheel is simply mounted on the back side of the stepper motor shaft. However, the stepper motor mount sure gets in the way of access to the backlash nut, and needs to be removed, a multi-step process. The only alternative would be to remove the entire mill and turn it on its side or back, or to have very tiny hands to reach up under the table. Tom Wade Hope, Indiana ------- Re: x axis backlash Posted by: "danp" danx~xxpines.co.il Date: Wed Dec 9, 2009 9:03 am ((PST)) Tom: from your description so far it seems that you will have to remove the stepper motor and check the long bolt which goes through the flexible cnc coupler and holds it to the feedscrew. regards dan pines sherline distributor, Israel ------- Re: x axis backlash Posted by: "draggingsteel" jmundy1234x~xxsbcglobal.net Date: Thu Dec 10, 2009 6:02 am ((PST)) In my experience with this set up I believe a few changes are in order. Remove all the nuts and screws on the leadscrew and coupler. Clean the end of the coupler and leadscrew with brake cleaner. Let dry. Small dab of blue threadlocker on the coupler screw; insert coupler thru stepper mount, install screw. Tighten securely, do not overtighten (I don't like ballend hex wrenches this small and don't ask why). Double nut the leadscrew at the stepper mount body. If using a 1/4-20 leadscrew, install a bolt with a nut on it in a drill, spin nut and bolt against a grinder to round (but still be able to maintain a small flat) the nut to be able to fit under the table when installed on the leadscrew. Make note of the original nut which has a recess which faces the carriage. Btw never tighten these nuts until the long screw on the coupler is tight. Since this double nut I have not had a repeat. It was weekly before. ------- Re: x axis backlash Posted by: "Tom Wade" tomx~xxwade.name Date: Thu Dec 10, 2009 9:44 am ((PST)) Been there, done that. It was tight. But the backlash nut itself was loose as a goose. Tom Wade Hope, Indiana ------- Help with X Axis Backlash Adjustment on mini mill. [SherlineCNC] Posted by: "Michael Jones" mach3x~xxmichaelandholly.com Date: Fri Dec 11, 2009 8:28 pm ((PST)) I have a D&M4s CNC Mini Mill that is (I believe) essentially an older style Sherline 5000 (the one with the pointer style backlash lock). I just finished a major rebuild of the on the mill to replace the original underpowered steppers and the old style chopper drivers with a new Gecko G540 controller/breakout system and new modern motors. So far, with only on exception, the rebuild has gone beautifully - I'm getting perfectly smooth .0006 ipm to 65 ipm rapid movement (I was able to cut acrylic at 20 ipm last night) up from only 9-10 ipm cutting and 15 ipm rapids. Here's the hitch. When I started, I had about .008" backlash on the X-axis. After disassembling, cleaning and reassembling the axis I'm getting .023" backlash. I've tightened the adjustment as well as I can in the available space (pretty tight inside the enclosure) but I'm still getting unacceptable backlash. I am considering designing an new "pointer" for the adjustment that meshes better with the backlash adjustment screw.. but that won't be until later. I've followed the instructions that I can find (which isn't very detailed). Any hints, ideas or insights on a better sequence or method to adjust for the backlash? Thanks, Michael ------- Re: Help with X Axis Backlash Adjustment on mini mill. Posted by: "Philx~xxYahoo" yahoox~xxphilmattison.com Date: Sat Dec 12, 2009 11:14 am ((PST)) Double check the set screw that holds the lead nut in place. I've found that sudden inexplicable increases in backlash are often caused by that not being tight enough. I filed a small notch in the lead nut to help lock it in position without having to tighten the set screw too much, as that can distort the nut, which causes binding. Phil M. ------- Re: Help with X Axis Backlash Adjustment on mini mill. SOLVED Posted by: "Michael Jones" mach3x~xxmichaelandholly.com Date: Mon Dec 14, 2009 8:57 am ((PST)) I figured out the problem last night. I was able to get .005 backlash. There were 2 factors: 1) The attachment of the lead screw to the X axis was slightly loose. There is a small adaptor on the end of the lead screw (a little different from the actual sherline part I believe) on one side of a thrust washer, and then a splined adaptor that fits in a link to the stepper motor on the other. There was a little space between the splined adaptor and the thrust washer connected to the axis.. I loosened the set screw and gave it a slight tap with mallet while bracing the other end of the lead screw on a block. Now when the screw moves the axis moves. 2) The pointer that locks the backlash nut into place was a bit loose. The tolerance on the screw hole is wide enough to drive a truck through - you have to press up on the bottom of the pointer to press it into the backlash nut or the nut will move on you as you switch directions. I'm considering reengineering both of these areas but haven't thought it through completely yet. Has anyone replaced the older style pointer lock with the newer style? Sherline's catalog says it won't work due to the hole spacing, but after closer inspection it could be done with a little ingenuity. I'd love to replace the lead screws with micro ball screws but don't that plan will go very far.. Anyone have any insights on this? Thanks, Michael ------- Re: Help with X Axis Backlash Adjustment on mini mill. SOLVED Posted by: "Tom Wade" tomx~xxwade.name Date: Mon Dec 14, 2009 10:22 am ((PST)) Couple of ways to go on this. Best way is probably just make the Delrin-AF nuts. Of course, this requires access to another mill, as the mill table has to be bored. Another way might be to just order a new mill table. $72.00 Another way would be to just drill and tap a new hole to take the new star washer. You'd probably want to build a fixture with two holes in it, so that you can locate the new hole the right distance from the leadscrew hole. Someone at Sherline could tell you what the distance should be. And, of course, the micro ball screw sounds interesting. Found a source for these? Tom Wade Hope, Indiana ------- Re: Help with X Axis Backlash Adjustment on mini mill. SOLVED Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Mon Dec 14, 2009 10:37 am ((PST)) Michael: You could replace the brass nuts with DelrinAF as I have described several times. End of problem. I use my mill commercially. No time for constant adjusting this & that. RichD ------- Re: Help with X Axis Backlash Adjustment on mini mill. SOLVED Posted by: "Michael Jones" mach3x~xxmichaelandholly.com Date: Mon Dec 14, 2009 11:28 am ((PST)) I've been considering the delrin-af version. That could be an interesting option but I'd rather at least try not to reinvent the wheel. I have a star washer upgrade kit on order from Sherline. I'll see what I can do when it comes. On the micro ball screw.. Nope.. I haven't found a source yet - that's the major hold up at the moment. I have found a few short ones, but nothing long enough for the x or y axis. The Z axis (if I go that direction) would be easier since it's a larger diameter. Doing a ball screw setup would also solve the issue of where the screw attaches to the axis. The ball screw nuts usually have a VERY stable zero slop adjustment method. Michael ------- XY table Delrin info [SherlineCNC] Posted by: "Jon" mc_n_gx~xxyahoo.com Date: Thu Dec 17, 2009 1:33 pm ((PST)) I have seen the Z upgrade in the folders. Where is the info on the table modifications for the Delrin nuts? I did a few searches but only found references to the Z axis and a metric conversion. ------- Re: XY table Delrin info Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Thu Dec 17, 2009 3:02 pm ((PST)) Jon: It's a series of pics in the Albums area under RichD's. RichD ------- Re: XY table Delrin info Posted by: "sherlineheretic" designnowx~xxsbcglobal.net Date: Thu Dec 17, 2009 3:29 pm ((PST)) If you look at "ken's misc" folder, there is a pic of the y axis nut I made. I basically just made longer versions of the stock nuts and installed them. I also did the x axis, but that is harder to see. What are you having trouble with, the left hand thread or the lengths and diameters and tap drill sizes? Ken ------- Re: XY table Delrin info Posted by: "Chuck Rice" Chuckx~xxWildRice.com Date: Thu Dec 17, 2009 3:53 pm ((PST)) Ken, I do not understand. That is a picture of the Backlash Nut, isn't it? You also have to replace the leadscrew nut too, don't you? I am interested in all the things you mentioned. What is the correct tap to use? Left hand and right 1/4-20 and what is the grade? Do you have an MSC or McMaster part number? The Z leadscrew is larger. Do you have the part-numbers for that too? I think that I can look up the drill size, given the tap size. So much to learn. Chuck ------- Re: XY table Delrin info Posted by: "sherlineheretic" designnowx~xxsbcglobal.net Date: Thu Dec 17, 2009 5:21 pm ((PST)) The nut inside the saddle is hard to see, except for superman... I'll see if I can take the thing apart this weekend, and send you pics of the version I did. I'll try to measure things a bit, and give you the dimensions. You can purchase the delrin af from MCMaster, that's where I got mine. Use a #7 drill for tap-drilling the thread. This will become clear in the pics, don't worry. It is worth doing! Ken ------- Re: XY table Delrin info Posted by: "Tony Zampini" zampini1x~xxcox.net Date: Fri Dec 18, 2009 4:37 pm ((PST)) Hi Rich: Regarding your DelrinAF low backlash nut design, do you happen to know if this modification can be done to the 4400 lathe crosslide? I don't have a Sherline mill, so I can't compare saddle dimensions. Thanks! Tony ------- Re: XY table Delrin info Posted by: "Tom Wade" tomx~xxwade.name Date: Fri Dec 18, 2009 5:21 pm ((PST)) I think that this has already been answered. Yes, it can be done, but why? On the lathe, you're only cutting toward the spindle, or toward the axis of rotation, so backlash is relatively unimportant. Tom Wade ------- Re: XY table Delrin info Posted by: "Tony Zampini" zampini1x~xxcox.net Date: Fri Dec 18, 2009 6:06 pm ((PST)) Tom: The reason it's important is because I don't have a mill. I use the Sherline vertical milling column with my lathe to do all my milling operations. Most of my parts are small, so this setup works fine for me. Also, I'm converting my lathe/mill to CNC, so reducing backlash would really be nice. Tony ------- Re: XY table Delrin info Posted by: "Tom Wade" tomx~xxwade.name Date: Fri Dec 18, 2009 6:34 pm ((PST)) I'm under the impression that the cross slide table is the same extrusion as the mill table, so I think that it would work. But, I've never done it, but don't see why it couldn't be done. Tom Wade ------- Re: XY table Delrin info Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Fri Dec 18, 2009 7:19 pm ((PST)) Tom, Hello ! This is the CNC group. Backlash is not allowed in any direction. Even on a lathe. Make an olive shape on the lathe for instance. You start with X coming toward you, then X goes away from you as Z travels constantly to the left. B/L in X is bad. Make a deep groove now. X goes in & out, but Z must cut on the right side then on the left. What will Z B/L do to that? H'mmm? RichD ------- Re: XY table Delrin info Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Fri Dec 18, 2009 7:34 pm ((PST)) Tony, I'm sure there's a way. I have not done mine yet, but a quick look shows there is very limited room with the stock parts. For a quick fix, boring out the existing brass nut hole to allow a thicker nut wall and making a DelrinAF nut will do, but the only B/L control (adjustment) is the setscrew squeeze. Of course the nut as tapped will be a close fit anyway due to the usual way plastic will expand as tapped and leaving an undersized thread. In this case that is just what is needed. If it's too tight, run the tap thru a few more times to loosen it up. The other concern is the nut is not very well captured and will move with in/out forces in spite of the setscrew. Something better is needed. The Mill method is perfect. The nut is in a blind pocket and the keeper nut allows squeezing for B/L adjustment. Rich ------- Re: XY table Delrin info Posted by: "Martin Dobbins" trainnutzx~xxyahoo.com Date: Fri Dec 18, 2009 8:31 pm ((PST)) Hi Rich, Tony, Actually I'm noodling this right now. You would have to be very careful because of the limited dimensions but if you could bore out sufficiently to create a blind pocket beyond which the delrin will not pass, you could then thread the first part of the hole and make a hollow brass nut as per your mill instructions in order to compress the delrin and prevent in and out movement. If the brass nut was partially split towards the inside end and the existing set screw was used to bear on and compress this area it would be much more effective. The brass nut would keep position and the compression would control rotation and backlash adjustment. The only trouble is space! This is a right hander but thinking about the mill, left hand taps tend to be expensive for single use (especially metric left hand taps -- try getting an M6.3X1 L H tap). In some cases spare Sherline leadscrews from the replacement parts list are cheaper; I'm wondering about making a tap out of a piece of one of those -- does anyone know if they are hardened? Martin ------- Re: XY table Delrin info Posted by: "Tony Zampini" zampini1x~xxcox.net Date: Fri Dec 18, 2009 8:44 pm ((PST)) Martin, I made a 3/8 - 20 left hand tap for the Z-axis delrin nut I made. Made it out of 12L14 and it cut the delrin like butter - no need to harden it. Tony ------- Re: XY table Delrin info Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Fri Dec 18, 2009 9:29 pm ((PST)) Tony, Martin, I too made my own 3/8-20LH tap (from tool steel) but I'm sure it would work fine soft. I used a ball end mill for the 2 flutes and filed the angular leading edges like a spiral point tap. The extra detail on the compression nut (on the X & Y) is not really needed as the plastic nut will be a tight fit from the get go. Just the slightest compression from the keeper nut will be all it needs. If your leadscrew has a worn area, you will lock up near the ends. So back off a tad. Standard HSS spiral point taps are what I used. 14-20 taps are a very handy size to have for other projects. RichD ------- Re: backlash and such distractions.. [SherlineCNC] Posted by: "Philx~xxYahoo" yahoox~xxphilmattison.com Date: Sat Dec 19, 2009 10:51 am ((PST)) G Warrier wrote: > Anyway, I would like to know if what I see with my 2010 mill is normal. I have a serious backlash in one direction of about 0.05" every time I move up the Z-axis and plunge down at any speed? This is a big bother when I do fly cutting as every time I run the CNC with tool lift I get the wrong cut depth and the stock is severly scored, not to mention the tool wear. Any help and a solution would be highly appreciated. I have the 4axis servo drive running DeskCNC. < I was vexed for years by the Z backlash until I discovered that the small 1/2" square bar of aluminum that offsets the vertical slide downward a couple of inches from the lead nut was flexing. No matter what else you do this will defeat you until you fix it. You can see how I did it at my web site: http://tinyurl.com/ydtrayy Phil M. ------- Re: backlash and such distractions.. Posted by: "Michael Jones" mach3x~xxmichaelandholly.com Date: Sat Dec 19, 2009 2:52 pm ((PST)) Just a thought here, but... Are you sure it's actually backlash? It could also be lost steps? a worn Z axis lead screw or nut? Loose connection between the Z axis nut and the z column? I was plagued by what I thought was excessive backlash on the X axis (a bit different... but as frustrating) until I found that it had very little to do with the lead screw, and more to do with how the lead screw was connected to the axis itself. Mount your dial indicator between your X and Z axis. If you have the ability, set your DeskCNC software to jog at .001 each time you press the jog z button. Then count how many times you have to hit the z jog until the DI actually registers movement, jog the other direction and do the same.. Michael ------- Re: backlash and such distractions.. Posted by: "G Warrier" g2warrierx~xxyahoo.com Date: Sat Dec 19, 2009 10:22 pm ((PST)) Hi Mike, I did all that and that's when I discovered the odd one way backlash. I could compensate this within DeskCNC using approximately 284steps. I wrote a short G-code to check this jog function using both G00 and G01 commands to move the axis up and down by 0.127, 0.254 and 0.508" multiple jogs in canned cycles (my dial gauge was inches while I have a metric screw!). I finally got the 284 steps. BUT THIS IS SOOO kludgey.... I think Phil Mattison may have found the real problem - I am going to try that anyway.... I am going to take the unit down and see where else I can stiffen the column. Another gripe I have is the brass lead screw nuts showed inside the cross tables with grub screws holding them in position.... they look really flimsy - in fact I had one of them come loose and Fred Smittle at Sherline asked me to loctite it just in case! Any slack in that can also cause X-Y axes backlash. g warrier ------- Re: backlash and such distractions.. Posted by: "G Warrier" g2warrierx~xxyahoo.com Date: Sat Dec 19, 2009 10:28 pm ((PST)) Phil: A good pointer although your photos cannot be enlarged to see your setup clearly for old folks like me. I am going to check the adjuster bar and also study the counter weight although many have discouraged from doing it. I am going to take my unit down this holiday period and go over everything that I can tighten up even if the shop is too cold for me to work in.... I have a technique to use ordinary springs to work as fairly constant force devices. Then again CF spiral springs can also be bought for about 20 bucks. Did you do those paintings? Wow! g warrier ------- backlash and such distractions.. [SherlineCNC] Posted by: "kencondal" kencondalx~xxyahoo.com Date: Sun Dec 20, 2009 10:31 am ((PST)) Hi All, I have been monitoring this group for the past month in anticipation of purchasing the Sherline Ultimate CNC package. I have a rather extensive woodworking shop but this would be my first venture into CNC and working with other materials (plastic, aluminum, brass, etc.). I must admit that these discussions about backlash and other inherent problems with the machines is scaring me off. Can someone please clarify if these issues: A. Are limited to older models (will my new machines need 'fixes' right out of the box)? B. Occur after many hours/years of use? C. Are significant if my projects tend to be more 'art' than 'fine precision' (I won't be building Swiss watches.) I'm really excited about getting involved in CNC, but would rather spend my time building projects instead of fixing faulty equipment. Thanks, Ken ------- Re: backlash and such distractions.. Posted by: "Dave Hylands" dhylandsx~xxgmail.com Date: Sun Dec 20, 2009 10:49 am ((PST)) Hi Ken, > A. Are limited to older models (will my new machines need 'fixes' right > out of the box)? All machines have backlash, even the multi-million dollar fancy mills. What's important is to understand backlash (i.e. what causes it) and also decide how important it is to minimize it. You can expect your new mill/lathe to have 0.003 to 0.007 backlash, and so far, I've never bothered to make any improvements to my mill and lathe. > B. Occur after many hours/years of use? The more you use it, the more it increases. All parts which run against each other will wear, so backlash will tend to increase over time. Also, since you tend to use the portion of your lathe which is closest to the chuck more, you'll get more slop near that end than you will near the tailstock. Again, this is a fact of life, no matter what lathe you buy. > C. Are significant if my projects tend to be more 'art' than 'fine > precision' (I won't be building Swiss watches.) The amount of backlash you and the amount of precision in the work aren't necessarily related. Yeah when you go from manual to CNC, it's nice to reduce the backlash, but if you understand what causes it, and design your parts appropriately, and then do the CAM stuff properly, it typically becomes a non-issue. Some people also get hung up trying to make everything within super tight tolerances, when often there is only one particular portion of a piece that actually requires tight tolerances. Understanding where the tolerances are actually needed, and where they aren't is also very beneficial. > I'm really excited about getting involved in CNC, but would rather > spend my time building projects instead of fixing faulty equipment. Exactly. The Sherline's are nice that way. You can get started right away. I've had my mill and lathe for nine years, and still haven't done any improvements in regards to backlash. It all depends on what you're doing. I've even purchased the CNC anti-backlash stuff from Sherline and it's still sitting in the box, waiting to be installed. Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ ------- backlash and such distractions.. Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sun Dec 20, 2009 11:07 am ((PST)) Hi Ken: Seconding everything Dave Hylands said. My experience with 2 Ultimate CNC packages (one at home, one at my workplace) is that they meet or exceed all of the tolerances, specs, and claims that Sherline makes for them. Right out of the box. And, with due care and diligence, will continue to do so for a very long time in a hobbyist environment. Buy. Enjoy. Keep in touch. David Clark in Southern Maryland, USA ------- NOTE TO FILE: REPLACEMENT DELRIN NUTS TO REDUCE BACKLASH. Tips on threading Delrin for this purpose appear in the Threading text file here starting Jan 1, 2010 with subject: "LH Internal thread cutting". ------- CNCizing [SherlineCNC] Posted by: "Tom Wade" tomx~xxwade.name Date: Tue Jan 5, 2010 9:02 pm ((PST)) On Saturday, January 02, 2010 Rubens wrote: > I have a lathe and a mill and lots of of accessories, and have always worked manually for years. Now, getting older, I feel tired of repeating some operations and then I'm wondering how it would be if I CNCize my mill. I always thought the backlash adjustments are too frequent, especially concerning Z axis, and I had to replace the saddle lock assembly 3 or 4 times (am I doing something wrong?). Question: could you pls tell me if you have backlash problems and how do you cope with the Z axis lock lever positioning? thanks Rubens < I don't have it, so can't say how it works. I removed the lock lever when I installed the cnc, per the instructions. Evidently, there are several different sets of instructions on this topic, which disagree with each other. But, there is a doodad (technical term) which you can install to hold the lock lever in any given position. http://www.sherline.com/4017Zinst.htm Tom Wade Hope, Indiana ------- Z-axis Touch Off [sherline] Posted by: "alenz2002" alenzx~xxbellsouth.net Date: Mon Jan 18, 2010 10:58 pm ((PST)) I've always used either a slip of paper or a feeler gauge to touch off the Z-zero to a part but in another forum a fellow describes a method of using a gauge of known dimension to set the tool height. He lowers the tool just a bit below the top of the gauge and then raises the tool until the gauge just slips under. His claim is that it is faster and safer (which I might challenge) but the thought occurred that it does set the Z-zero with the backlash taken out on the safe side, i.e., the tool will be on the bottom of the backlash thus preventing unexpected drops due to the tool being pulled into the work. Any thoughts? Al ------- Re: Z-axis Touch Off Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Mon Jan 18, 2010 11:08 pm ((PST)) Hi Al: This is the method I use too...it's more accurate than the paper shim method, less likely to gouge the part by overshooting, kinder to the cutter (especially small cutters) etc etc. I use a 0.100 gauge block that a former employee trashed on one side... it's still accurate enough over most of its surface to be useful for this sort of work. Cheers Marcus http://implant-mechanix.com/splash.html ------- Re: Z-axis Touch Off Posted by: "botwire" botwirex~xxyahoo.com Date: Tue Jan 19, 2010 6:24 pm ((PST)) I'm new to all this but wouldn't you still have the problem of the backlash when the tool is raised to jog to the starting position and then lowered to start cutting? I would think it is better to zero with the tool moving down rather than down then back up. Perhaps I am missing something. ------- Re: Z-axis Touch Off Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Tue Jan 19, 2010 7:37 pm ((PST)) Hi Botwire: The weight of the head tends to hold the head at the bottom of the backlash, effectively removing it on that axis only. Besides, I use the method on my Haas and Defiance too...both have ballscrews so there's no backlash there. Cheers Marcus http://implant-mechanix.com/splash.html ------- Re: Z-axis Touch Off Posted by: "markotime" markotimex~xxshaw.ca Date: Wed Jan 20, 2010 6:51 am ((PST)) Hi, Marcus! Except that after a Z up and down, slide friction will keep it from falling to the bottom. And with small cutters things won't get sucked down into the workpiece. Gravity may eventually win, but the error in depth will be profound if backlash is present. This will show up in spades with PCB milling, for example. Gravity almost always wins with ballscrews and slides - on the Prolight as well mark ------- Re: Z-axis Touch Off Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Tue Jan 19, 2010 8:02 am ((PST)) Al: If "Z" axis depth is critical, I set up as follows. First the mounted cutting tool is lowered until it touches the work piece with the Mill in the off position. After the cutting tool touches the work piece it is raised .005". Next the Mill is turned on. I then lightly engage the "Z" axis saddle locking lever part number 40175. When held in the lightly locked position it will remove "Z" axis backlash. While holding the lever, I very slowly lower the cutting tool until it ever so slightly touches the work piece under magnification. From this point while still holding the lever, the depth can be accurately set in either direction by handwheel settings without backlash effects. This method can be used hands free with Sherlines "Z" axis backlash lock option. (P/N 4017Z) Jerry Kieffer ------- Leadscrew backlash lock [sherline] Posted by: "Harry Brill Jr." proaudioguyx~xxyahoo.com Date: Sun Mar 14, 2010 8:19 am ((PDT)) Just noticed the CNC lathe has a leadscrew backlash lock. What does that do? Does it make any sense to add this to the manual lathe? Would love to get rid of the backlash. Harry Brill Jr. ------- Re: Leadscrew backlash lock Posted by: "wongsterwish" wongsterwishx~xxyahoo.com.sg Date: Sun Mar 14, 2010 8:46 am ((PDT)) It's the same as the one found on the mill's z axis. It is to reduce (or eliminate?) backlash by tightening the brass lever and locking it in place with the plastic lever. You may find it harder to turn in manual mode, at least that's what I felt. Regards, Wong ------- [SherlineCNC] Refitting the Star Gear backlash adjustment to an older mill? Posted by: "Michael Jones" mach3x~xxmichaelandholly.com Date: Fri Feb 4, 2011 3:09 pm ((PST)) Has anyone attempted to refit a pre-2004 sherline cnc mill with the newer "star gear" format backlash adjuster? I was considering an attempt but wanted to find out if anyone else had made a similar (successful or unsuccessful) attempt? Thanks, Michael Auburn, WA ------- Re: Refitting the Star Gear backlash adjustment to an older mill? Posted by: "Rich Dean" toolman8x~xxcopper.net Date: Fri Feb 4, 2011 6:19 pm ((PST)) Michael, There is a better more secure, easier way to do this. In my folder is a small easy to make part that replaces the star washer. RichD's Mods & Tools: RichDNutLockingClamp-A.jpg RichDNutLockingClamp-B.jpg Cheers, RichD ------- Re: Back Lash Adjustment on A2Z Mill [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Tue Apr 26, 2011 10:33 am ((PDT)) "m0nkshon0r" wrote: > I read just about every post regarding back lash, somewhere/someone > said they fab'd a new brass nut (50200?) except made it 3/4" long. > I think the person said it helped. That person may have been me. See message #31902 http://tech.groups.yahoo.com/group/sherline/message/31902 [ NOTE TO FILE: That message and discussion is also here; look for David's message earlier in this file "Minor mod, good result" Thu Jan 25, 2007 ] That was just over 4 years ago, don't believe I've had to touch anything with regard to backlash since. I'm guessing I use the mill maybe 10 hours a week, manual and CNC. Checked it a few minutes ago in the process of centering the rotary table under the spindle: just under .002 in each axis. I consider this normal, reasonable and acceptable. I have a lot of plans for a major rebuild of my shop and some equipment mods this summer. One of the things on the list is to experiment with PTFE delrin leadscrew nuts, or maybe casting them around the screw with a mix of graphite and epoxy or casting resin. Just for fun, of which as always there is way too much to have and not enough time to have it. I'll post any useful results. David Clark in Southern Maryland, USA ------- Sherline backlash [taigtools] Posted by: "Lester Caine" lesterx~xxlsces.co.uk Date: Thu May 19, 2011 8:15 am ((PDT)) OK - I've not had to play with this one yet, but is it possible to adjust the backlash on the sherline rotary table? The one on the machine I was overhauling today is pretty bad and needs something doing to it. The table I use myself has an eccentric shaft position but I don't think that the sherline has any adjustment? Lester Caine - G8HFL Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk// Firebird - http://www.firebirdsql.org/index.php ------- Re: Sherline backlash Posted by: "Ron Thompson" bareboogerx~xxcfl.rr.com Date: Thu May 19, 2011 8:37 am ((PDT)) "Worm backlash can be minimized by moving the worm housing to compensate for wear. To adjust, loosen one of the two socket head screws that come up from the bottom and hold the worm housing to the body of the rotary table. Lightly tap the housing with a plastic mallet to move the housing (and worm shaft) tighter into the table gear. When backlash has been reduced to less than 1/10°, retighten the screw." Quoted from: http://www.sherline.com/3700inst.htm Ron Thompson ------- Re: Anti Backlash for Lathe X axis [SherlineCNC] Posted by: "EngFromSantaClara" ldmillerx~xxastound.net Date: Thu Jul 28, 2011 7:08 pm ((PDT)) "Joe Rhys Fastiggi" wrote: > Has anyone every installed the anti backlash nut for the Lathe X axis? It doesn't seem to be any different than the setups for the mill. I would assume you only need the nut and retainer to install on the back side of the saddle. Does anyone know why it doesn't come with anti backlash for the lathe X axis? < With a lathe, anti-backlash is not very important because you are always cutting in the same directions. Even with CNC it is easy to program so that you always cut coming in toward center and toward the headstock. Because of where the cutter is, you can always over-travel away from the part and feed coming in. I don't have any anti-backlash on either X or Z, and I have no trouble making 0.0005" accuracy on CNC parts. Most big lathes have quite a lot of backlash. Making the saddle real tight hugely increases the load on the operator(!) and wears the screws and ways. On the other hand, in milling you can be cutting in any direction, so anti-backlash is very convenient for hand control and absolutely necessary for CNC. Larry ------- Re: Anti Backlash for Lathe X axis Posted by: "imserv1" imservx~xxvectorcam.us Date: Fri Jul 29, 2011 5:55 am ((PDT)) > With a lathe, anti-backlash is not very important because you are > always cutting in the same directions. There are many lathe features that require precise control of backlash. In most cases you do NOT cut in the same direction for roughing and finishing when cutting complex profiles. What you have said is true for simple diameters and shoulders, but start adding angles, arcs, Corner radii, and tangencies between arcs and angles, and backlash control becomes very critical. Turned part features that are affected by backlash include: Grooving with both sides of a grooving tool to make a groove wider than the tool (Z backlash). Concave and convex diametral turning will leave a serious witness mark when the X axis changes direction. Trailer hitch and tooling balls for example. Software based backlash compensation may or may not help. Threading is critical to have backlash control as the chip lay will affect the tool position within the free play zone of the backlash, potentially spoiling the thread flanks. Cut off, chip can pull the tool into the workpiece, causing breakage and spoiled parts. This is prevented with a low or zero backlash setup. Drilling, you don't want the center of your drill (center drill) moving around if you are trying to drill through a tit on the end of a part (X backlash cntrol). Also if drilling in copper you don't want the tool jerking the saddle toward the workpiecs (Z backlash). Large lathes that are not CNC have a lot of backlash and manual operators who make simple cuts. Large CNC lathes have extremely precise ball screws with preloaded nuts and thrust bearings that permit no backlash or end play. Many Sherline lathes are used with live tooling and that can also bring backlash into play exactly the same as a milling machine. There may not be room to install the Mill backlash adjuster components into the saddle of the lathe. Even if you did fit it in, it will be a nightmare to adjust it. Fred Smith - IMService http://www.imsrv.com ------- NOTE TO FILE: There was a bit of back and forth after Fred's message, but Fred's opinions are based on his considerable experience using machines. ------- Re: How do you know if you have backlash issues? [SherlineCNC] Posted by: "Steve" s.bromleyx~xxcomcast.net Date: Sat Sep 3, 2011 11:05 am ((PDT)) Use whatever kind of indicator or travel dial you have to check the movement of your machine. Move the machine in the + direction, zero out the indicator and machine. Move a bit further in the + direction, then move back until the indicator reads zero. Whatever the machine reads is your backlash. Well, really close anyway. ------- Re: How do you know if you have backlash issues? Posted by: "wongsterwish" wongsterwishx~xxyahoo.com.sg Date: Sat Sep 3, 2011 6:17 pm ((PDT)) > This leads me to a followup question. For the X and Y antibacklash nut, > how do I turn it? I read in the manual that you should turn it to secure > it, but I can barely put a grip on it. Is it ok to use pliers I suppose > but that may rip the external threads (which I suppose is only for > holding the nut in position). So it's ok to just use pliers to turn it > after unscrewing the 'star' nut? I use a small plier to turn the star nut for backlash adjustment. Have to do it bit by bit so as not to cause too much damage. I managed to strip one totally and had to replace it a year back. The 2 nuts are rather hard to turn... Regards, Wong ------- Lathe Cross slide backlash [taigtools] Posted by: "Gaston Gagnon" gaston.gagnonx~xxvideotron.ca Date: Sat Mar 30, 2013 2:30 pm ((PDT)) I have CNCed my Taig lathe but I have around 0.007" backlash on the cross slide. How would you go to minimize or even remove this backlash? Thanks, Gaston ------- Re: Lathe Cross slide backlash Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Sat Mar 30, 2013 3:29 pm ((PDT)) 1) adjust the feed nuts; 2) if you are using the standard Taig shaft couplers, toss them & use proper antibacklash couplers, for example Oldham couplings. Regards, Tony ------- Re: Lathe Cross slide backlash Posted by: "Gaston Gagnon" gaston.gagnonx~xxvideotron.ca Date: Sat Mar 30, 2013 5:35 pm ((PDT)) Thanks Tony, I suppose you are talking about what Taig calls the "Crosslide Screw Nut"? How do you adjust that nut and how close to 0 backlash can you get? Gaston ------- Re: Lathe Cross slide backlash Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Sun Mar 31, 2013 3:02 am ((PDT)) That's right. They are slit longitudinally and can be nipped up a bit to adjust for wear. However, on a CNC lathe, for most purposes backlash isn't an issue. Regards, Tony ------- Re: Lathe Cross slide backlash Posted by: "Douglas Vogt" dbvogtx~xxyahoo.com Date: Sat Mar 30, 2013 5:49 pm ((PDT)) Do you have any opinion on Oldham couplings versus beam or helical couplings like the type Sherline uses? ------- Re: Lathe Cross slide backlash Posted by: "Steve Blackmore" stevex~xxpilotltd.net Date: Sun Mar 31, 2013 12:55 am ((PDT)) Avoid helical couplings. They can wind up under load and then are not "zero backlash" couplings. They are fine driving an encoder or the like with little or no load, but perform poorly on a machine axis. Use Oldham couplings -- they are backlash free. Steve Blackmore ------- Re: Lathe Cross slide backlash Posted by: "Jeffrey Birt" birt_jx~xxsoigeneris.com Date: Sun Mar 31, 2013 8:37 am ((PDT)) As with most things the devil is in the details. Beam/helical/bellows couplings are fine when they are used within the torque ratings they are designed for. Sherline designed their couplers for use with 150 oz-in motors and they have no big problems when used accordingly. When someone thinks that they 'have' to use 380 oz-in motors (or larger), the couplers become the weak link. Beam/helical/bellows type couplings can be harder to use as you may have to be able to access both set screws when the motor is mounted to get things lined up properly. They can be had in a 'zero backlash' design as well. Oldham/spider type couplings can be easier to use as each half of the coupler gets mounted separately. If you need to take the stepper off for maintenance reasons, this type is usually easier to work with. This type of coupling is not by default 'zero backlash' but they can be had in that tolerance level. The Taig stepper couplers are a very unique design and work well given that you adjust them properly and realize you will need to replace the straws periodically. They may not be as nice or as handy to use as the Oldham style but they do work well. Before worrying about the coupler you have to worry about getting the motor and lead screw into alignment. You want them aligned as nearly perfectly as you can get. A lot of homemade designs try to use four standoff posts to mount the motor. Not only does this not give you much in the way of torsional stability but it is almost impossible to try and keep the motor and lead screw in alignment. There is a reason the motors are made with the mounting boss on the nose. Taig and Sherline both use a tube type coupler which works well and is easy to use. When you are choosing a coupler you have to not only worry about backlash but also the amount of torque it will have to transmit in operation. Many hobbyist type products are something some guy whipped up in is shop so you really have no idea what amount of torque it can handle on a continuous basis or how accurately it is made, w.r.t. bore accuracy and alignment, etc. Many of the cheap Asian import parts are not much better. Even when working with quality parts you have to pay attention to the degree of misalignment a coupler can tolerate. Even high misalignment couplers will quickly fail when used outside their design limitations. In short there is no one best type of coupler. You have to find one that fits the job at hand and use it within its deign specifications. A great resource to find out more about different couplers is: http://www.mcmaster.com/#standard-shaft-couplings/=m49pcj Jeff Birt Soigeneris.com ------- Re: Lathe Cross slide backlash Posted by: "Gaston Gagnon" gaston.gagnonx~xxvideotron.ca Date: Sun Mar 31, 2013 9:15 am ((PDT)) The backlash I get comes from the "Crosslide Screw Nut", not from the coupler. You are right, Mach3's backlash compensation seems to work well. However, I would appreciate being enlighten on the practical effect of the backlash on the quality of the cutting and also on the tool? To operate the lathe by hand, I added an encoder on each axis and made a screen with large indicator in Mach 3: http://public.fotki.com/Gaston-Gagnon/taig-micro-lathe-1/encoder-for- cnc-manual/pictures/screen-r21.html That works well except contrary to gauges directly linked to the machine, tool offset is, but backlash is not, compensated for in the encoder reading (as far as I can see). DumpsterCNC sells an anti-backlash nut but it is right handed thread and also a bit bulky to be used on the X axis. Gaston ------- Re: Lathe Cross slide backlash Posted by: "Jeffrey Birt" birt_jx~xxsoigeneris.com Date: Sun Mar 31, 2013 9:22 am ((PDT)) Squeezing the nut will make it tighter and reduce backlash, same idea as the adjustment screws on the adjustable couplers on the mill. Jeff Birt Soigeneris.com ------- Re: Lathe Cross slide backlash Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Sun Mar 31, 2013 9:50 am ((PDT)) > How do you squeeze the leadscrew nut? There isn't the same adjustment > mechanism that exists on the mill. You squeeze it in a vise, to compress it so that it's tighter. I find that it's best done in a small drill press vise with smooth sides. I use a set of feeler gages to determine the existing slot width. Then I insert a feeler gage about .003-.005 thinner than the slot width into the slot and squeeze to compress. Test for fit, and repeat as needed. Putting a smaller feeler gage in the slot will keep you from compressing it too much as it's very hard to open the nut up again after squeezing. ------- Re: Lathe Cross slide backlash Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Sun Mar 31, 2013 9:58 am ((PDT)) Backlash is only an issue when you are changing the direction in which the backlash is taken up. On a lathe cross-slide, this doesn't happen under normal conditions, so it isn't an issue. It doesn't have any effect on the quality of cutting as you are always cutting when the backlash has been taken up. Backlash in the leadscrew is more of a problem -- for example if you were cutting a chess piece or similar shape -- because going from cutting up to a peak to cutting down to a valley there is a reversal in the direction in which the leadscrew backlash is taken up. However, for "normal" turning -- tapers, plain turning to a shoulder, threading, etc., backlash in either feed screw isn't a big deal, any more than it is for manual turning. Regards, Tony ------- Re: Lathe Cross slide backlash Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Sun Mar 31, 2013 3:57 pm ((PDT)) On 3/31/2013, Gaston Gagnon wrote: > What is the best backlash you can get with this method? About a thou or three with the new ball bearing leadscrew. On 3/31/2013, Yi Yao wrote: > How well does it hold up after this procedure? Does it tend to deform > back? Yes, it will always wear back over time. The tighter you adjust it the quicker it will wear. But it will hold up for a while. What Tony said generally about backlash not mattering as much is true though. ------- Re: What have I got and how to fix backlash [SherlineCNC] Posted by: "Andy M" trumpy81x~xxoptusnet.com.au Date: Wed Dec 11, 2013 10:49 am ((PST)) michael4230 wrote: > Hi I have a Sherline mill serial number SP 71442. Can anyone identify > what it is and the age. It has the tapered motor mounts and is fitted > with MicroKinetic steppers. The control box was removed and I have made > a new control to run with Mach3, The leadscrews have a nut behind the > bearing in the motor mount and Z has a lever to set the rotation of the > nut. If I tighten the nut, for example on Y then the bearing starts to > squeak so I guess I should look at the nut, but what is the procedure. > Help will be appreciated. Mike GDay michael4230, Sorry, I have no idea what year your Mill is. Sherline would probably know though, and from all accounts they are friendly and helpful there, so drop them an email. The nut behind the bearings on the stepper mount is for preloading the bearing and it should not be set too tight, otherwise you will damage the bearings. It should be locked in place with a little loctite too. The backlash adjusters should be on the saddle for both X and Y axis. They are splined brass nuts and held in place with a star or pointer style lock if it's an old Sherline mill or a splined washer if it's a newer model mill. Sherline can provide replacement bearings for your stepper mounts and backlash nuts should you need them. Regards Andy M ------- Re: What have I got and how to fix backlash - links and answers to b Posted by: "William Cox" wtcox_listx~xxcomcast.net Date: Sat Dec 14, 2013 2:15 pm ((PST)) For the age of a Sherline tool, assuming no upgrades, see http://www.sherline.com/usedmach.htm . Generally I look first at the motor control - square = DC motor, newer and better. Rectangular is older, not as steady or powerful at slower speeds. Backlash compensation on a mill saddle runs from the oldest (pointer and star nut on the saddle for X and Y) to newer (coarse tooth gear meshing with the star nut) to newest (finer tooth gear meshing with a finer star nut). The latter two have a different hole spacings than the star and pointer. I'm working to update the antibacklash on my two older Sherline mills, and am planning to bore the new hole and use a helicoil for the 8-32 BTW. If it works I'll post pictures on the Sherline group. There are several variations on the Z axis antibacklash; see (b) below. If you have a star thing meshed with a star thing you're in luck - just get the parts to replace if worn. Here's a recent post I did on the Sherline group - the better place to look for this information, though the membership overlaps a lot. Message is at http://groups.yahoo.com/neo/groups/sherline/conversations/messages/58760 (you must be a member). > The earlier email from Jerry said "Tomorrow, the shipment of the > Sherline Lathe Anti-Backlash Upgrade Kits is/are due. ( P/ N 40950)". > Just to be clear, this is the upgrade to ADD a saddle-mounted > antibacklash nut and screw to a lathe that does not have one already. > > There are several other items that came to mind when this thread > started. > (a) 5011U is an upgrade if you already have the star but it's the > older (1997-2004); you might not have the anitbacklash setup at all on > an older lathe. You cannot easily go to this if you have the pointer > version. See http://www.sherline.com/5011uinst.pdf > > (b) The 4417Z (leadscrew, not for the lathe saddle) and the > corresponding mill part 4417ZM. I have it on my CNC-ready lathe and my > very not-ready mill. Works as intended. See > http://www.sherline.com/4417Zinst.pdf > > I have two older mills with the pointer backlash arrangement, and the > hole spacing isn't the same as the star wheel :-( > > I'm considering boring a hole at the tap size of a helicoil insert at > the right spacing to use the newer; I find the pointer to be at best a > pain. Hope the helicoil with stand up long term. ------- Re: What have I got and how to fix backlash [Following are excerpts from this thread on the Sherline group and are mixed with perhaps discussion of another Sherline lathe mod. It would be wise to read everything about mods and upgrades at Sherline's company website.] William Cox Dec 5, 2013 [The first part of this message repeats the quote: "The earlier email from Jerry ...... stand up long term."] On the 8-32 drill - to procter and others in metric countries: Consider an M4 screw of the right length and thread to match your Metric taps. At most a bushing (it's a tiny bit smaller than the major diameter of a number 8-32 screw) would let you use it, and a bushing for the tap drill could be used in the Sherline hole positioning jig. The stress on the screw is not such that a slightly smaller M4 screw should be a problem IMO. Probably a lot cheaper and simpler than obtaining an 8-32 tap and appropriate screw, though I'd be happy to send you a tap - contact me off line. Don't know shipping but there's not much weight. The screw comes with the 40950 I believe. I also have more 10-32 taps than I'll use in a lifetime (GREAT buy on eBay :-) and would throw in a few. bill cox > Hi Jerry, Why? Because its something I might need to do to my Sherlines at some time in the future. Would have to buy such odd size drills and taps for the job from the US as they're not readily available here. It's annoying to start a project and then have to leave it for weeks until XYZ arrives. On the plus side, when I had Unimats it could take many months to get small parts whereas US firms will handle small orders quickly. Greg.Procter, Hukerenui, New Zealand. < --- kwstse Dec 5, 2013 Hi William, I'm not keen on mixing metric and US threads on the same machine! When one is concentrating on a project it's very easy to forget the rest. For a long time I've had the intention of painting all the US bolt/screw heads orange but I always seem to have more important tasks. I still have my old Emco lathes (SL and Compact 5) and loads of accessories and tooling made over 45 odd years. At least I know "Sherline - US", "Emco - metric", "GLP - metric" but I'm scared of the day when I get it wrong or when I put a US drill or tap down on the bench while concentrating on the task in hand. Greg.Procter, Hukerenui, New Zealand. --- Hi, I live in a metric country so small that it does not register on any scale exept when we deviate from some norm. I can go to two shops in town and expect to get any imperial tap or die conceiveable from two different sources and the choices are Swedish or Danish. Iceland went metric in 1910 but the transition was slow and American cars used to be popular here till the sevnties so that may explain it. Is it really diificult to get imperial taps and dies in New Zeeland? Regards, Flosi in Iceland metric since 1910 --- > Album; > "Sherline Lathe Upgrade" > Photo shows the underside of my Sherline Lathe 4000 short bed crosslide > with the unit installed. > Jerry G (Glickstein) Hi Jerry G What is the advantage of this upgrade when working without cnc? The first book I read about lathe work was the one by Joe Martin and in it he says that you have to work against the play. That has always worked for me. What is the gain in doing the upgrade? regards, Flosi in Iceland --- Thayer Syme Dec 6, 2013 Flosi, My lathe is manual and while I understand always working in from the same direction to offset the backlash, I would like to reduce what I have. My cross slide is up around .015 backlash and every once in a while I will get caught when I back off not quite enough. If I can get that down under .005 easily that would be a big help, I think. Thayer --- kwstse Dec 6, 2013 Hi Flosi, don't put your nation down, everyone knows where it is and that you're famous for racing drivers, lakes, midges, sand flies, Nokia and historically thrashing the Russian Army. (I guess that's politically incorrect to mention but ...) Northland, where I live, is full of ship builders, logging and large farming equipment. If one asks for imperial taps and dies one gets offered items as small as one inch and large enough to fit container ship propellors. They will order in smaller items but that takes weeks and costs! Much quicker to order direct from the US. Could order from Auckland/Wellington/Christchurch but it takes just as long and costs more. We didn't go metric until 1972, and had British/Australian/Canadian vehicles. Umpteen different UK thread standards plus US inch types. We even got cars with metric and inch nuts and bolts on the same vehicle. Having had numerous classic vehicles over the years, often with odd nuts/ bolts replaced with whatever was handy over the years, I've become a bit fussy =8-)> Greg.Procter, Hukerenui, New Zealand. ------- kwstse Dec 6, 2013 Ok Flosi, you can shoot me now! I had it in my head you were from Finland. Pressed send and then noticed you're in Iceland. (Famous for Denmark and volcanoes) Greg.Procter, Hukerenui, New Zealand. --- Flosi Guðmundsson Dec 6, 2013 Hi Greg You are mixing us at least partly with the Fins which is a strange coincidence as today is THEIR Independece day from the Russians. Ours was six days ago. We have lakes but they are miniscule compared to theirs. Our oppressor were the Danes and they were rather beneign as oppressors go. Here in the isolation we have mostly had to be our own enemies. There has only been one war here. It was a civil war and ended in total defeat of everyone involved in 1262. I'm sitting here in my geothermally heated apartment and it is unusually cold. We have gone long way from the times when my forefathers wrote the sagas on calfskin in between killig each other with weapons made of lousy iron and burning down almost the total wegetation of the country. But we did preserve much of Europes litterature and folklore. The future is bright though. It's getting warmer at least. And the sun does shine 24 hr in the summer. Some say that the Irish people who came here first called the island Sóley (Sunny island) Our politicians are not getting any brighter thogh. Best regards, Flosi in politically incorrect Iceland --- kwstse Dec 6, 2013 Hi Flosi, sometimes we mill in the lathe. Climb milling with play can be a disaster. (Have finally found my atlas!) Greg.Procter, Hukerenui, New Zealand. --- glicker31 Dec 6, 2013 Reduces the backlash. Jerry G (Glickstein) --- Flosi Guðmundsson Dec 6, 2013 I have also experimented with milling in the lathe and found that play in the x axis is preventing me from getting good results. The reason why I wanted to do milling with the lathe was that I wanted to make a portable machining kit that would be as compact as possible. We were talking y axis here or am I mistaken? Regards, Flosi --- Andy M Dec 6, 2013 GDay chieftoolmaker, I have always wondered why Sherline didn't include this mod, especially on the CNC ready Sherline lathes. I'm not overly fussed with it's design although it works well enough on the mill. Did you have any difficulty fitting the mod? Does Sherline provide a template for drilling the holes? Since my 4410 is basically stock, I've been thinking of adding this mod in one form or another. Regards Andy M --- JERRY G Dec 6, 2013 GDay Andy, Yes, the existing bore is only .375" diameter. Kind of small. I was inclined to open it up to .500" diameter, or make a new drum. Definitely related. Project is temporarily halted while I upgrade my lathes with the new Sherline release; P/N 40950 (Lathe Backlash Upgrade Kit) Was going to do all three, but the good news is, the last Sherline 4000 short bed lathe I received on April 19,2013, already had the 8-32 threaded hole in the saddle! Therefore I only have to do two. Regards, Jerry G (Glickstein) --- JERRY G Dec 6, 2013 GDay Andy, I like it on the mills so that is why I bought three units for my lathes. One saddle was already drilled and tapped 8--32 for the upgrade, saving me some work there. Two to go. Yes, Sherline included a drill jig. As follows; 1.000" diameter obviously stock steel, maybe 12L14. Flange is .374" wide. Plug is .3115" diameter, by .303" long. ( Goes into the Slide Screw Insert hole for pick up) A hole for the tap drill is # 29 ( .136" diameter) Appears to be .375 " from the center of the plug. Goes through the flange for spotting/drilling. There is a scribed line about .250" above the tap drill hole and across the flange for aligning the jig horizontally. I have choices. 1. Follow the instructions, hold or clamp the jig to the saddle, align by eye, and drill and tap. 2. Measure the hole location from the pick up plug diameter precisely, and set up the saddle in a mill for the drilling and tapping. Am inclined to # 2 because of my background. Will measure all the jigs for identical placement of the tap drill hole location. Stay tuned for further reports. Jerry G (Glickstein) --- Andy M Dec 6, 2013 GDay JERRY, Thanks for the detailed reply Jerry. If I was to order one of these I think I would take your approach and do the drilling in the mill. Regards Andy M --- glicker31 Dec 7, 2013 Album; "Sherline Lathe Upgrade" Photo shows one method of measuring the C/C of the tap drill hole and the locator post on the drill jig. A close fitting drill shank in the tap drill hole, and a Jo Block fitted between it and the post. A better way is to use a DTI. Jerry G (Glickstein) I forgot to mention. Why only two drill jigs shown when Sherline had shipped three? The third is wrapped and will be shipped at my post office later when they open to a gentleman who requested it. He is a member here, has been on the since its inception and just recently joined my < Toolroom Group> Take a bow, William C. Jerry G (Glickstein) --- glicker31 Dec 7, 2013 Album; "Sherline LAthe Upgrade" Photo shows the first use of the some of the hardware supplied with the High Tech Plate. A surprise. Measurement came up with .385" between the .3115" diameter post and the # 29 ( .136" diameter ) tap drill hole. Gonna ask my West Coast counterpart, Mr. Fred Smittle. Sure looked like a nominal 3/8" to me. That was by scale, though. Later, Jerry G (Glickstein) Still waiting for Fred S. No response yet. While waiting, I measured drill jig # 2. Same, about .385". Jerry G (Glickstein) --- glicker31 Dec 8, 2013 Maybe Fred S. took an extended holiday combined with Thanksgiving. He is a member of my Glick Model Shop Group since Oct. 15, 2006. I know he will contact me. Meanwhile, I will conduct a test of the Sherline P/N 40950 Lathe Backlash Upgrade by drilling and tapping the tooling plate on my Sherline Mill. First, the ,375" nominal dimension. Next, the .385" dimension I measured on the two remaining drill jigs. Report will follow. Jerry G (Glickstein) --- glicker31 Dec 8, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows the Test Hole Group. Upper Dimensional Combo Works! Star Gear Lock and Backlash Nut are meshed. Surface of the Sherline Tooling Plate represents the face of the saddle. Jerry G (Glickstein --- Sherline Lathe Backlash Upgrade / "A Closer Mesh with Thee" glicker31 Dec 9, 2013 I am going to run one more test before I set up the two saddles of my Sherline 4000 Short Bed Lathes. (See the subject line) (C/C distance will be reduced to get an optimum meshing of the Backlash Nut and the Star Gear Lock) Jerry G (Glickstein) --- glicker31 Dec 10, 2013 Update; Bored a CRF * hole in the Sherline tooling plate. * = Close Running Fit For the protrusion of the drill jig(s Will measure again and compare my findings to the report from Fred S. of Sherline due today, before I commit to the modification of the saddle(s) Later, Jerry G (Glickstein) )Watching the snow fall :( --- glicker31 Dec 10, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows set up for establishing the reference location for the protrusion of the drill jig(s) which will replicate the instructions from Sherline. (Surface of Sherlne tooling plate represents the front of the saddle(s) This is for the people who are thinking of getting the P/N 40950. Full report when Fred S. of Sherline replies. Jerry G (Glickstein) --- glicker31 Dec 11, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows the final C/C distance between the star lock gear and the backlash nut. It is .3670" as given to me by Fred S. of Sherline I drilled and tapped an 8-32 hole in the tooling plate. For the 8-32 button head screw that will secure the star lock gear. Moved over .3670" (in x axis) Drilled and tapped 1/4"-20 for the Sherline cross slide lead screw. On the lead screw I threaded the backlash nut. They mesh nicely, and do exactly as designed. Jerry G (Glickstein) --- glicker31 Dec 12, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows; Central hole is .3120" diameter. Sherline P/N 40890 ( Slide Screw Insert ) will be pressed in. Hole at 6 o clock is 8-32 tapped. Was drilled with drill jig # 1 Hole at 3 o clock is 8-32 tapped. Was drilled with drill jig # 2. Later, components will be assembled and results reported. Jerry G (Glickstein) --- glicker31 Dec 15, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows a purple block of machinable wax. There are three sets of holes. 1 & 2 are .3120" diameter. For the pick up pluigs on the drill jigs. Going to secure the drill jigs to the block and drill with a Bosch Electric Hand Drill. Third set has two holes. Tapped 8-32 and 1/4"-20. At the specified .3670" C/C distance. Assemblies will be made and a report posted. When? Later, Jerry G (Glickstein) --- Re: [sherline] Sherline Lathe Backlash Upgrade / Plan B (58863) glicker31 Dec 16, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows ingredients for Plan B. Listing later, You all know why. Jerry G (Glickstein) --- Re: [sherline] Sherline Lathe Backlash Upgrade / Plan B (58863) Ian Newman Dec 16, 2013 Hi, Unfortunately, due to the "personality" of the Neo updates, I'm currently unable to see the pics posted by Jerry, so I'm unsure what "Plan B" involves. Hence, the comments below may be irrelevant or simply repeating the option pictures by Jerry. The method usually used to set the optimum spacing of wheels in a clock or watch is through the use of a tool called a "depthing tool" -- a picture paints a thousand words: http://pennyfarthingtools.co.uk/horological/depthing-tool-3/2012/04/29/ The two gears to be meshed are supported between the two pairs of parallel centres and the spacing adjusted for optimum meshing. The adjustable frame allows the gear mesh to be tested and the centre distances adjusted until the "feel" is just right. (This is important in horological applications where the spacing is made to incorporate a controlled degree of "shake") The outer ends of the depthing tool centres are ground to sharp points and they are used as divider points. Without changing the depthing tool setting, the scriber ends are used to scribe and mark the centre distances on the material that will carry the gear bearings. No measurement involved and a perfect gear spacing achieved. A simple and easily made version of the tool can be constructed from a door hinge: http://mb.nawcc.org/showthread.php?87223-Door-Hinge-Depthing-Tool All the best, Ian --- Plan B Listing (58866) glicker31 Dec 16, 2013 1. 3/4" by 1" by 4 1/2" 6061 Aluminum 2. 1x pkg Sherline P/N 40890 (Slide Screw Insert) 3. 1x P/N 40890 (Slide Screw Insert) 4. 2x Sherline Drill Jigs (from P/N 40950 Kit, this applies to Item Numbers 4, 5, 6, and 7 ) 5. 2x Allen Socket Button Head Screws 8-32 by 1/4" 6. 2x Star Gear Locks 7. 2x Anti-Backlash Nuts 8. Sherline P/N 44210 (Cross Slide Lead Screw) Jerry G (Glickstein) --- Sherline Lathe Backlash Upgrade / Tools for Testing glicker31 Dec 16, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows the array of tools to be used in the testing. Jerry G (Glickstein) --- glicker31 Dec 17, 2013 Album;"Sherline Lathe Backlash Upgrade" Photo shows result at .3670" C/C Distance. My West Coast counterpart, Mr. Fred Smittle aka "Toolmaker Fred" has helped me once again. It's a go for my other two saddles. Jerry G (Glickstein) --- glicker31 Dec 17, 2013 [and further posts the next few days] Album; "Sherline Lathe Backlash Upgrade" Photo shows the set up to align the saddle to the X axis. Album; "Sherline Lathe Backlash Upgrade" Photo shows the start of a new set up to get more Z headroom. Had to switch from my Sherline 5400 Mill to my Sherline 2000 Mill. Album; Sherline Lathe Backlash Upgrade" Photos a DTI reading * on the slide screw insert hole in the Sherline saddle. * = Dead Nuts Album; "Sherline Lathe Backlash Upgrade" Photo shows that ,3670" C/C is "Da Place" :) Album; "Sherline Lathe Backlash Upgrade" Photos show Sherline Forest, and a Sherline 4000 Short Bed Lathe brought front and center to secure the saddle for drilling and tapping. ( Set Up on Sherline 2000 Mill was left intact for the purpose.) Tip* * = never break up a set up until it is absolutely necessary. Album; "Sherline Lathe Backlash Upgrade" Photo shows the result on the third and final saddle. Album; "Sherline Lathe Backlash Upgrade" Photo shows the set up after the last saddle was shipped off to the assembly department. A good time to re-check the Tram on the 1" by 2" by 3" block. Album; "Sherline Lathe Backlash Upgrade" Photo shows my idea. Since I have finished installing three Sherline P/N 40950. I came up with this. Modified an existing spanner wrench from one of my mikes. Dremel-ed and filed. Album; "Sherline Lathe Backlash Upgrade" Photo shows the method I use to set the play of the saddle gib. No play, no movement. Jerry G (Glickstein) --- Re: Sherline Lathe Backlash Upgrade / Idea of the Month (58920) redmiataowner1997 Dec 25, 2013 I like it! I know I kept those extra wrenches for a reason. Thanks for sharing. Ron --- Re: [sherline] Re: Sherline Lathe Backlash Upgrade / Idea of the Month (58921) JERRY G Dec 25, 2013 Hi Ron, no problem. One thing though. I have to refine my idea. Have to provide two "teeth" on the wrench for driving. There will be a photographic update if I am successful. Healthy, Happy Holidays to you and yours. Jerry G (Invited to a Xmas dinner at a next building neighbors. :) --- New Photo / Sherline Lathe Backlash Upgrade (58923) glicker31 Dec 26, 2013 Album; "Sherline Lathe Backlash Upgrade" Photo shows the method I devised. Jerry G (Glickstein) ------- Re: upgrade a 2000 mill [sherline] Posted by: "Martin Dobbins" trainnutzx~xxyahoo.com Date: Sun Feb 16, 2014 8:10 am ((PST)) On Sat, 2/15/14, jack wrote: > I have a Sherline 2000 mill I bought new a few years back. I have not used it much as I had a Wabeco mill with ball screws I used a lot. I am downsizing and have sold the Wabeco. I want to use the Sherline mill but I am finding a lot of backlash especially on the "Z" axis. I want to install ball screws but I have not been able to find a ball screw kit sold by an after service supplier. Does anyone know of such a kit ? If I can not find a kit what suggestions are there to improve the backlash using the screws Sherline sells. I know there has been quit a bit written about backlash on the Sherline equipment, just wondered what your thoughts are. Thanks Jack < Hi Jack, As Greg suggested A2Z do aftermarket add ons for Sherline, they supply leadscrews from Kerk Motion which are not ball screws but an accurate alternative. http://www.a2zcnc.com/ People have also made Delrin nuts for the existing leadscrews, it's a DIY job but results are supposed to be good. There are some examples floating about in this group's photos and files area, here is one example: https://groups.yahoo.com/neo/groups/sherline/files/Al%27s%20Proj ects/Z-Axis%20Saddle%20Nut%20Mod/ Hope that helps? Martin ------- Re: upgrade a 2000 mill Posted by: jlkiefferx~xxcharter.net n2562001 Date: Sun Feb 16, 2014 9:59 am ((PST)) Jack. The leadscrew clearance on the standard Mill is such that it will not permit the space required for ball screws. However, Sherline makes modified parts for an after market supplier that permits ball screw installation. You would have to contact Sherline for further information. Again however, If the mill is to be used in the manual mode, ball leadscrew pitches are too course for accurate control of the Mill. X and Y axis backlash is adjustable on current production mills and leadscrew pitches allow for accuracy and control. The Z axis backlash is controllable on current machines by holding the locking lever to light resistance when limited backlash is desired. You can also install the CNC "Z" axis backlash adjusting fixture to control backlash to what ever amount you desire. Again you can contact Sherline for options. Jerry Kieffer ------- Re: Rebuilding 5400 Mill - focus on backlash adjustment update thoug Posted by: "William Cox" wtcox_listx~xxcomcast.net wtcox_nj Date: Mon Feb 17, 2014 8:54 am ((PST)) On 2/12/14 10:38 AM, Mikey D wrote: (IN PART) > I'm also uncertain about the value of trying to change the backlash > adjustment. Mike and others -- I've been thinking through updating the pointer-style backlash adjustment on my 5400 and an A2Z base with an old saddle. This note addresses my current thinking; Mike's post pushed me to get this out instead of stalling further. I think it's a big improvement; I've had issues with the resolution of the pointer lock (and dropping the ^$^#* thing), so I've been toying with this idea for quite a while. The problem with the newer gear-style backlash adjustment is that the hole spacing is off from the pointer; see http://www.sherline.com/5011uinst.htm (for 5011U) for details. " It will not replace the pointer system because the hole centers are further apart on the star gear design" Proposal 1: Locktite a 6061 aluminum screw (8-32 as I recall) into the cleaned hole. Let set. Use a milling cutter to put a hole in the right place, which will overlap the screw plug. Drill to size, tap, and install new backlash nuts and the appropriate screw. Proposal 2: Go off to the side; there's clearance. Do a new hole, not quite touching the existing. Workholding for both: Alas, the horizontal conversion is waiting on the backlash update...so I'd clamp to the Sherline right angle block (3559 or 3561) held to the table with T-nuts and also clamped. I have two faces for each saddle, and I'm not sure how well clamping on the side would work, so it would mean resetting and redoing for each of the two screws. Proposal 3: Stop thinking about it. I was strongest on Proposal 3 for a while, then Jerry G mentioned the jig for the lathe cross slide backlash; I'd use the same setup (and his dimensions - thanks so much Jerry for documenting your work!) for the lathe saddle. I have a just-too-old CNC ready long bed lathe. So what problems/issues do folks see on Proposal 1? There's not a lot of meat for Proposal 2. Since the setup would be virtually identical for the mill and lathe saddles, I'd do all three with one setup. I think the mill is the better choice versus wandering drill bits, though my old Craftsman Commercial Split-head drill press has proven to be very accurate, with TIR under half a thou (needle hardly quivers on a 0.001 dial indicator). Thoughts from Mike and the rest of you? ------- Ballscrew options? [SherlineCNC] Posted by: tj.petersenx~xxgmail.com blynxyz Date: Tue Dec 2, 2014 12:42 pm ((PST)) Does any one know of a replacement ball-screw option for the Z-axis on a 5400 mill? I mainly use my mill for carving exotic woods and my lightly used mill came without the backlash compensator on the Z nut. Thus I am losing a bit of detail, and thought I'd heard of ball screw options for Sherline. Thanks for your time and input, Tim ------- Re: Ballscrew options? Posted by: dtbarberx~xxsti.net danieltbarber Date: Wed Dec 3, 2014 6:50 am ((PST)) Tim, Although this is not a ballscrew, the modification does add good anti-backlash adjustment to a Sherline Z-axis. I used the information presented on the website to make a similar modification to my Sherline 2000 mill. I liked the results well enough to make a similar modification to my Sherline lathe. Dan http://hamrx8.com/A2Z_Antibacklash_Project.html ------- Re: Ballscrew options? Posted by: timgx~xxktmarketing.com timgoldstein Date: Wed Dec 3, 2014 1:16 pm ((PST)) Not sure the issue with the A2Z website as we are here, taking orders, making parts, and getting lots of web traffic. Yes we use Haydon Kerk screws. It is a MAJOR project to design a saddle and mount system for them and turn the ends to work with Sherline couplers. We sell it all done for you or you can have one of those projects where there are great parts still sitting in the box for the project to get started. I will warn everyone about ball screws. It means far more than just one thing. Yes they all work about the same in theory. In practice there are major differences between rolled and cheap or ground and expensive as well as over loaded balls, double tracks, double nuts, etc. We used to make a special run of our Monster Mill in black for a single customer we finally fired because they were too hard to deal with. They sent us their choice of USA made rolled screws with standard balls in the nuts from what I can tell. We machined the ends and installed them. They were crap and far worse than the Kerk units we use. You can find their ads because they brag about their mill having balls. I was getting .006 - .010" backlash on all axes I tested. This is 2 - 3 times worse than the Kerks will yield on a bad day. So great bragging and marketing to have "Balls" on your mill, but a disaster in the shop. So feedback from a guy that has spent probably $20K in the last 5 years on various screw systems for testing and production is the subject is complex, integrating them into a machine is a MAJOR task (just the saddle is 5 ops and any oops and you scrap that one and move on to the next). Ball screws are even worse as the specs we normally are not the whole story. Additional like most things more $$ is generally better quality, higher accuracy and precision, better durability, and better support. Hope this helps, Tim G A2Z Corp A2Z CNC division www.a2zcorp.us/store ------- Re: Ballscrew options? Posted by: "Jeffrey Birt" birt_jx~xxsoigeneris.com jeff.birt Date: Wed Dec 3, 2014 1:30 pm ((PST)) Amen Tim. Ball screws have become to hobbyist machinist what ‘billet’ parts are to gear heads. Jeff Birt Soigeneris.com ------- Re: Ballscrew options? Posted by: "Hannu Venermo" gcode.fix~xxgmail.com hvenermo Date: Wed Dec 3, 2014 10:01 pm ((PST)) Agree with Tim. Some cheap screws are good, most are not, and you need to know what you are doing to tell the difference. The most important criteria are rigidity, followed by repeatability. All else flows from that. Fwiw.. I spent 3k€ on just 11 screws, a while back. Of course, i mostly use 40 mm and 32 mm diameter. ------- Re: Ballscrew options? Posted by: dtbarberx~xxsti.net danieltbarber Date: Thu Dec 4, 2014 7:47 am ((PST)) Tim, Not certain why the link did not work for you. Use the following link http://www.ghqp.com.au/ http://www.ghqp.com.au/ It should take you to Graham's home page. Click the "Projects" button and then scroll down to the bottom of the page. Click the Sherline A2Z link and you will see lots of images of the modification. Download the zip file and you will have dimensional drawings. I made his first iteration, which was a two piece unit. There is enough detail there to make the part without difficulty. For clarity, the A2Z reference is to the approach that Tim Goldstein (A2Z owner) used to add Haydon Kerk (HK) leadscrews and anti-backlash nuts to the Sherline X & Y axis enhancements that he offers. I have both and have been very pleased with their performance. To my knowledge, Tim is not offering a similar modification for the Z-axis. Tim is a member of this group, perhaps he will comment regarding the possibility of A2Z offering this option in the future. Regarding part numbers, I purchased my leadscrews and anti-backlash nuts off Ebay from a seller in CA that was selling off old inventory. I do not have the actual part numbers but you should be able to use Graham's dimensional drawings and find something suitable from HK. If I were doing it over again, I would use the same HK leadscrews and nuts offered by A2Z. They are more robust than what I purchased on Ebay. The biggest challenge was machining the taper on the end of the stainless steel leadscrew and drilling and taping it to mate with the Sherline coupler. To minimize breaking the tap I went with the next larger screw size and correspondingly enlarged the hole in the Sherline coupler. Hope this helps. Dan ------- Re: y-axis backlash nut stuck [SherlineCNC] Posted by: gp_illustratorx~xxyahoo.com gp_illustrator Date: Mon Aug 10, 2015 4:07 pm ((PDT)) OK, so everything is smooth, but I know I'm missing something. I tighten the backlash nut snug against the saddle and it stays put for a while, but it eventually wanders off. What am I missing? ------- Re: y-axis backlash nut stuck Posted by: jowhowhox~xxyahoo.com jowhowho Date: Mon Aug 10, 2015 5:00 pm ((PDT)) Backlash Adjustment on Sherline Tools http://www.sherline.com/backlash.htm Adjusting Backlash on Sherline handwheels What is backlash? Backlash is the amount the handwheel can turn before the slide starts to move when c... ------- Re: y-axis backlash nut stuck Posted by: "William Cox" wtcox_listx~xxcomcast.net wtcox_nj Date: Tue Aug 11, 2015 8:00 am ((PDT)) gp_illustrator -- > I tighten the backlash nut snug against the saddle and it stays put > for a while, but it eventually wanders off. What am I missing? I suspect you're missing the star point or star gear locking of the antibacklash nut. If that's not done it will indeed loosen. See jowhowho's link to the Sherline instructions. BTW if you have the star pointer, there are a number of posts in the Sherline yahoo group on how to upgrade to the star gear. The star pointer is very coarse and IMO very fiddly. bill ------- ------------------------------------------------------------------ This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------