Machining plastic may need machine speeds and cutters/tools and techniques significantly different from those used for metals, woods, and other common materials. Hopefully there are some tips in the following conversations that will help you. SAFETY HAZARDS. Please note carefully that plastics and related materials mentioned in this file may have increased health and safety hazards that will require special safety precautions and protective equipment and safety measures beyond your usual shop practices, and far beyond whatever may be written here. Be safe and consult OSHA [or the equivalent health and safety government organization in your state or country] for laws, regulations, rules and recommendations for what you are about to do, and follow them. Always consider leaving dangerous materials and procedures to competent professional companies; contract out that unsafe work and only do the totally safe bits yourself. You are engaging in a hobby and owe it to yourself and your family to be prudent, careful, healthy and long lived. 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 more than 70 additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/ 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. If you do not have those most recent official instructions, acquire a copy through the manufacturer before operating or using their product. Where the company no longer exists, use the appropriate news or user group to locate an official copy. Be careful -- original instructions may not meet current safety standards. Updated safety information and operating instructions may also be available through a local club, a local professional in the trade, a local business, or an appropriate government agency. In every case, use your common sense before beginning or taking the next step; and do not proceed if you have any questions or doubts about any procedure, or the safety of any procedure. Follow all laws and codes, and employ certified or licenced professionals as required by those laws or codes. Hazardous tasks beyond your competence or expertise should also be contracted to professionals. Let's be really careful out there. (c) Copyright 2003 - 2008 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. ======================================================================== Date: Thu, 03 May 2001 20:12:53 -0000 From: ptolemyx~xxbellsouth.net Subject: Plastic Gears Hi- Does anyone h experience to share regarding milling plastic gears in the 0.5" - 2" range (1 - 5 cm ;)? Has anyone used either nylon or Delrin? Thanks, Neil ------- Date: Thu, 03 May 2001 20:41:23 -0000 From: n2562001x~xxyahoo.com Subject: Re: Plastic Gears Neil: Standard or single point cutters will work fine. On nylon and other soft plastic use a backer behind the blank to get a clean cut. You may also need to cut a little deeper to get proper tooth fit. depending on the application you may also want to use a little larger tooth profile for strength. Jerry Kieffer ------- Date: Thu, 3 May 2001 16:04:11 -0700 From: "Keith Yundt" Subject: Re: Plastic Gears Neil, I have cut some bevel gears out of delrin to replace some G scale steam loco gears for my neighbour. I have used a flycutter for mine, and the only thing I would add to what Jerry said is that delrin seems to "stretch" alot. I drilled the gear out to fit a shaft, using my lathe, and when I went to put it on the shaft I was amazed to find that it was very(too) tight. The only thing I could think of was that it "stretched" during the drilling; maybe I was crowding it too much when I drilled it, I'm not sure. Otherwise, though, it cuts great and you should have no problems. Keith Yundt ------- Date: Fri, 04 May 2001 01:38:40 -0000 From: ptolemyx~xxbellsouth.net Subject: Re: Plastic Gears Thanks Jerry and Keith for the info. A website I visited mentioned the tendency of Delrin to stretch while being machined and then to relax. The context there was that holes drilled by reaming might have a slightly smaller than expected final diameter -- presumably having been temporarily deformed under pressure during cutting. I tend to budget some of the stock for experimentation -- I'll report any interesting results. Neil ------- Date: Thu, 3 May 2001 20:42:51 -0700 From: "Marcus & Eva" Subject: Re: Plastic Gears Hi Neil: Delrin is the material to use. It machines a lot better than nylon and has excellent strength. It also has a low coefficient of friction. Many molded plastic gears are Delrin. Cheers Marcus ------- Date: Mon, 11 Jun 2001 17:30:55 -0500 (CDT) From: Tom Benedict Subject: Re: Re: Delrin On Mon, 11 Jun 2001, Ken Jenkins wrote: > I agree entirely. I really like the material in terms of end results > and the many different ways you can use it but it is kinda nasty > /stringy to turn. I haven't experimented much with different tool > profiles or angles maybe some adjustment in that direction would make > working with it easier I don't know. I've cut Delrin, Nylon, UHMW, PVC, and a couple of other plastics. Except for acrylics, just about all of them are stringmeisters. Some acrylics have the opposite problem, and crumble under the tool, making for nasty dust. (I'll take the stringies, personally.) Tom ------- From: David Beierl Date: Thu Aug 2, 2001 9:06 am Subject: Re: [atlas_craftsman] acetal At 07:55 AM 8/2/2001, Ron Odum wrote: >Can someone please tell me a little about an alloy (?) know by the >name or Acetal or Delrin? http://americanplastics.net/page90.html Do google on "delrin properties" you'll get plenty. david David Beierl - Providence, RI USA 6 (or 3)" Atlas lathe ca. 1941 ------- From: helpx~xx4... Date: Thu Aug 2, 2001 9:23 am Subject: Re: [atlas_craftsman] acetal Delrin is a trade name for acetyl- it cuts well turns well, but it is somewhat brittle, and can crack and chip without too much effort. It is highly used in electrical connector work, and is a cood insulator for electrodes, and current carrying wires. It is available in colors and has good chemical resistance. Black is good at duplicating small injection molded pieces which can no longer be found. Regards, George O'Connor ------- From: tadici283x~xxc... Date: Thu Aug 2, 2001 9:45 am Subject: Re: [atlas_craftsman] acetal mattking... writes: > >Can someone please tell me a little about an alloy (?) know by the > >name or Acetal or Delrin? Tough stuff, takes a lot of abuse, machines well with sharp tools no great odor like some other plastics, can be formed into nearly anything. I can't think of anything out of the ordinary, does make better gears than plastic. Chris of Bradenton FL ------- From: "Mac Goekler" Date: Thu Aug 2, 2001 4:33 pm Subject: Re: [atlas_craftsman] acetal Hi Rod, Delrin (DuPont) or Celcon (Celanese) are plastics (Acetal polymer) that have certain self-lubricating properties (no fun to mold -- mold surface gets a wax like, para-formaldehyde coating). Great for gears, bushings, bearings, etc. You will need a sharp tool to machine. As plastics go -- it is much like nylon -- except for the lubricating issue. Have fun, Mac from Ohio ------- From: cravdraa... Date: Sat Aug 4, 2001 6:54 am Subject: Re: acetal One of the favorite machinists there is S .K . Grimes, a machinist for large format photographers, he uses Delrin to make new lenscaps for old LF lenses: http://www.skgrimes.com/ Alex ------- From: catboat15... Date: Wed Aug 15, 2001 5:50 pm Subject: Re: [atlas_craftsman] turning Plexiglas rod Scottx~xxB... writes: > ... does anyone on this list have any experience I have turned a bit of PVC pipe to make various things for myself. Machines quite nicely. But to machine plexiglass and similar the problem is two parts. One is the heat of cutting can melt the plastic, Two the chips stick to everything, tool, work piece, yourself. Keep everything cool and machining is no problem. Use plenty of rake and clearance on the tools. Finished work can be polished with toothpaste or you can use a solvent to get rid of the "frosted" appearance of the plastic after cutting. John Meacham High Desert of California, Palmdale, Littlerock. ------- From: Jon Elson Date: Wed Aug 15, 2001 10:49 pm Subject: Re: [atlas_craftsman] turning Plexiglas rod scott Bonelli wrote: > I'm new to this list.. I joined because it looked like a good place > to start learning about lathe work. I am interested in learning how > to turn plastic rod, as well as aluminum. I assume that turning > Plexiglas rod is similar to working with metal.. Only in the most general terms. Plexiglas (Rohm&Haas trademark for acrylic) is brittle, produces immense heat when cut, and tends to gum up around cutting tools. So, there are a number of tricks to cut it without major problems. > I thought I would pick a few brains before purchasing a machine. > Does anyone on this list have any experience working with plastics? > .. is anyone on this list located in the New England area? > I'm located in Rhode Island, and am trying to hook up with someone > who knows what they are doing, before I jump into this. I've done a number of plastic parts over the years, acrylic, Teflon, PVC, etc. They are all a little different, but the problem of the plastic getting hot enough to melt and then gumming up on the cutter is nearly universal. I'm in St. Louis, so you can't drop by for a chat too easily, but I'll be glad to share what I know. Jon ------- Date: Sat, 15 Sep 2001 18:05:58 -0400 From: "Mac Goekler" Subject: Re: PVC turning question From: >>I've been turning 3" solid PVC on the Sherline with riser blocks. This material lets me take heavy cuts at a fast feed with the highest speed. The swarf streaming onto me is very hot. Is there any danger of this stuff catching fire or should I slow things down? I'm not using cutting fluid. Todd << Hi Todd, PVC will not burn. If you get it too hot it will degrade into HCL gas (nasty stuff). Normally, soapy water is used as a lub. Good Luck, Mac from OHIO ------- Date: Sat, 15 Sep 2001 21:38:54 -0400 From: "Mac Goekler" Subject: Re: PVC turning question > Thanks. If it starts turning into HCL will I be able to smell it? Will > water rust my HSS and carbide tools? Todd Hi Todd, Yes, you will notice the HCL (hydrochloric acid)-- it will drive you from the room. I've been asked if it was poisonous -- my response is that you will have left (or been driven) from the premises long before it'll do you any damage. It will corrode almost any metal (not gold). I've taken deep cuts on rigid PVC with not real problem. Soapy water will rust your tools if left in it -- but not if you dry them off promptly. PVC tooling requires lots of relief and rake. Carbide will certainly last longer than HSS. Good Luck, Mac from Ohio ------- Date: Sun, 11 Nov 2001 10:43:19 -0600 From: Richard Meredith Subject: Re: Turning skate wheels LADDERBARx~xxaol.com wrote: >> This is what I'm trying to do, Turn wheels from a set of roller blades From 82 mm to 76 mm. The reason is my wheels are bigger than my sons and when you skate you wear out the wheels. So instead of throwing my worn ones away I want to make them fit my sons. (am I cheap or what)LOL. The wheels are harder rubber 84 duraumiter I tried to cut them with a very sharp H.S.S. bit and a carbide one. Didn't work. So I started to file them -- very time consuming. Any suggestions appreciated. << Hello Mike: Having machined both hard rubber, and soft plastics on a lathe, I have found that a very, very, positive rake tool, and lower surface footage works best. You need to slice the material off much like wood turning, not scrape off as really more the effect on soft material with most metal working tools. Keeping the surface footage down helps control heat buildup on the tool. Most larger cities have at least one automotive tire dealer with a tire lathe. (Yes they do turn tires to true them up!) You might want to call around and see which dealer has one, and pay them a visit. The scale of the tooling is wrong, but it might give you some ideas. Good Luck, Rich ------- Date: Sun, 11 Nov 2001 10:00:41 -0600 From: Bill Aycock Subject: Re: Turning skate wheels In most cases of trying to cut rubber, the problem is the friction. The problem is - it sticks- then distorts, pulling the material into the blade. Most machining of rubber-like products is helped by lubricating the cut area with water. If this is not possible- try using a disc sander on the rotating wheel. Hope this helps- Bill ------- Date: Sun, 11 Nov 2001 08:15:51 -0800 (PST) From: Don Smith Subject: Re: Turning skate wheels Mike, I just machined a urethane skate wheel a few days ago and had no problem at all...using a carbide bit with a narrow rounded tip. As far as machining the ones you have, maybe it would be worth a try to put them in the freezer for awhile before machining. Regards, Don Smith ------- Date: Wed, 27 Mar 2002 19:34:50 -0000 From: "rpm2290028" Subject: Re: Turcite, or Moglice In atlas_craftsmanx~xxy..., "n5fee" wrote: > I have seen this epoxy mentioned a couple of times recently on this > list. I have searched the archives and see it mentioned in passing > in a couple of other messages, but I cannot find information about it > by searching the web. Who makes these products and where can > information about it be found? Thanks, Dallas Shell, 6 in Atlas Dear Dallas, I do a lot of work in plastics, so am familiar with many different types. Turcite is not an epoxy, it's a specially made plastic for bearings that is similar to acetal/delrin in machining chatacteristics. It's bearing properties are somewhat like graphite impregnated nylon, only more efficient. Unless you really have to, you should try to design/work around Turcite since it's fantastically expensive. I recently bought a foot length of 3/4" rod for $14.00. The thinner sections are three or four times that, I believe because it is more difficult to make in that size. ------- Date: Wed, 6 Feb 2002 18:45:35 -0600 (CST) From: Tom Benedict Subject: Re: Boring a water jacket On Wed, 6 Feb 2002 ajkdfwx~xxaol.com wrote: > I'm trying to make a water cooling jacket for an Astro Flight motors > for my scale boat. It will be about 2" long. I feel the best way to > seal this is with rubber O-rings at each end. I have been fooling > around (without much success) with PVC pipe as I have not found any > thick walled aluminum tube as yet. Check if there are any local industrial metal suppliers. They can usually get whatever you need (at cost). Better yet, check the local scrap yards and see what you can find. > The OD of the motor is 1.315 and I'm trying to use sched. 80 PVC (it's > thicker) with an OD of 1.75. Has anyone out there tried to bore PVC? Yep! > What are the best speeds for this on the Taig? The big problem I ran into when I was making PVC parts is that any kind of heat at the tool can melt the PVC. Rather than rig a pump coolant system for water, I opted for slow speeds and fast feeds. Nothing outrageous, but you're aiming to get the plastic out as a nice continuous strip. One more caution on that: If you get it going just right, the chip will shoot out to one side. Great! But it can very very easily catch on the chuck, cross-slide, whatever, and grab. If it looks like you're going to have grabby swarf, turn off the motor and clear it before taking the next cut. It's no fun when it grabs. Best advice is to chuck up some cheap PVC fittings you don't care about (like sched 40 caps, which are less than a buck apiece), and play with it. Try some different spindle speeds and feeds, using different tool geometries. You'll hit on a combo you like. > How do I go about boring it out and still leave enough on each end to > make a channel for the O-rings? Do I need a special type of boring bar? Shouldn't think so. Just design your part geometry in such a way that you've still got room for the o-ring. > Lots of questions ... any help will be greatly appreciated. No problem! PVC's pretty neat to turn. Just be sure the part doesn't leap out of your chuck jaws! It's a truckload more flexible than aluminum! Tom ------- Date: Mon, 22 Apr 2002 19:03:59 +0100 From: "Graham Knight" Subject: Re: machining acrylic I do quite a bit of work with acrylic, the secret is to use CAST acrylic not extruded, it machines much better but is more expensive. Most acrylic rod you will find is the cheaper extruded type which can be very difficult to machine; you should really try to find a supplier who stocks cast and knows the difference. If he doesn't know what it is then it's almost certainly extruded as they just stock the cheapest they can get, unless they are aware of a special need for cast material. Graham in London, England SAM35 & 1066 Raynes Park MAC Secretary http://website.lineone.net/~raynes.pk.mac/ ------- Date: Wed, 1 May 2002 11:50:10 -0400 From: "Daniel Munoz" Subject: machining / polishing Acrylic Last time I talked here about my experience in machining Acrylic, someone said that he had experience with it. Graham I think ? I'm searching a way to polish acrylic at final to restore the transparency. With a simple shape like a rod, I can manage it, with very fin sandpaper (grid 2000), and also some polishing compound applied with a cloth. But it is a long and fastidious process. When the shape is complicated, I have difficulties to restore the polish properly. Is there some tricks about this material one could share ? Thanks, daniel ------- Date: Wed, 01 May 2002 09:56:39 -0700 From: Craig Chamberlin Subject: Re: machining / polishing Acrylic Hi Daniel If I remember correctly, you can flash a torch (using a big tip) over the surface and it will clear up. Takes a little practice. Ciao, Craig ------- Date: Wed, 1 May 2002 18:00:17 +0100 From: "Graham Knight" Subject: Re: machining / polishing Acrylic None that I know of, I usually use a polishing compound like T-Cut to get the final scratches out. Most of my acrylic work gets a final finish of sprayed 2-pack acrylic lacquer, any minute scratches disappear completely once it's sprayed, but I don't know if you want to do that, or have the facilities to do it? Graham in London, England SAM35 & 1066 Raynes Park MAC Secretary http://website.lineone.net/~raynes.pk.mac/ ------- Date: Wed, 01 May 2002 10:29:31 -0700 From: Randy Gordon-Gilmore Subject: Re: machining / polishing Acrylic A fix used by modelers is to dip the clear parts (windshields etc.) in Future floor finish (full-strength), let the excess drain off and hang to dry. Future isn't a polish or wax, but is actually some kind of acrylic emulsion that dries glossy. A lot of people also airbrush it (again, full-strength) as a gloss clearcoat for their models. Best regards, Randy (who has not tried the dipping process--only read about it!) ------ Date: Wed, 1 May 2002 18:49:08 +0100 From: "Graham Knight" Subject: Re: machining / polishing Acrylic 2-pack acrylic is a lacquer/hardener system mostly used for automotive refinishing, it's very easy to get a good finish with it, much easier than the old cellulose paints. It does require the use of a decent mask, one rated for organic vapours, and proper ventilation, but it's not as hazardous as some materials. The brand I use is Mipa, or a more expensive one called Glasurit, both made in Europe I think. I don't know if either of these is available in Canada but you should be able to find something similar. Visit your local car repairer and ask, they may sell/give you a small amount. Randy's comment about floor polish reminded me that I have used Johnsons Klear for this purpose too, it works quite well when sprayed then polished, but it's probably not as durable as the 2-pack acrylic. Graham in London, England SAM35 & 1066 Raynes Park MAC Secretary http://website.lineone.net/~raynes.pk.mac/ ------- Date: Sat, 16 Nov 2002 17:17:42 -0000 From: "timgoldstein" Subject: Re: Delrin/Acetal--Best Milling RPM, Best Lubricant? In sherline..., "variousgroups" wrote: > Anybody have any advice about the best rpm to use for milling > Delrin/Acetal and is there a best lubricant to use? Delrin is easy. I have cut it dry, with a light spray of water based coolant from a mist cooler, and with flood coolant (water and cutting oil) in a spray bottle. All seemed to work just fine, but the surface finish may have been slightly nicer with either coolant. As far as speed goes I use about the same as aluminum (in other words crank it up) with about double the feed of aluminum. The stuff cuts like butter and if you go too slow the tool scuffs a lot and gets hot. Tim [Denver, CO] Sherline at Deep Discounts www.KTMarketing.com/Sherline ------- Date: Sat, 07 Dec 2002 21:39:23 -0800 From: "Scott A. Stephens" Subject: Teflon I plan to use Teflon in a project. But the Teflon will be part of a seal and I need a really smooth finish to make this work. So guru's, which is better for cutting Teflon??? HSS, or carbide???? ------- Date: Sun, 08 Dec 2002 01:08:30 -0500 From: RichD Subject: Re: Teflon Scott, Either one, as long as its ***SHARP***. Top rake may help as well. RichD ------- Date: Sun, 8 Dec 2002 14:00:50 -0500 From: "David Simmons" Subject: Re: Teflon Scott: Look at most Teflon's as if you are about to cut free machining aluminum. But make sure your tools are at peak. Very sharp!!! Also your RPM should be a little higher - and the cut depth should be fairly deep, even on the finish cut - Teflon defects badly. I have supplied my son - 12 now - with a fair amount of Teflon to give him a chance to understand his lathe and tools before he can damage anything. It is that easy to work with! Later, Dave S. ------- Date: Mon, 06 Jan 2003 17:52:48 -0000 From: "Paul Smith " Subject: Machining Solid Carbon Rods Does anyone have any experience in machining carbon/graphite rod? I saw some solid carbon rods on the glass-supply.com website and I was wondering if they would be suitable for a project that I am working on. Specifically I was wondering if standard tools (cutters, drill bits, cutoff tools, etc.) were suitable or if I would need something different. I guess my major concern is that the carbon may be too brittle and just shatter. Thanks, Paul ------- Date: Mon, 06 Jan 2003 12:00:07 -0600 From: Ron Roske Subject: Re: Machining Solid Carbon Rods Paul: Can't really help on the machinablity aspect, but their 1/4" rods are only $1.50. Your question may be answered best by getting one of those and writing the $1.50 off to R&D. I may do that myself, just out of curiosity. RonR ------- Date: Mon, 6 Jan 2003 12:12:01 -0600 From: "Nance, Tom" Subject: RE: Machining Solid Carbon Rods Hi Paul: The pistons for Jerry Howell's sterling engines use graphite rod. I have made 3 of them so far and have had no trouble with the graphite. Like you, I was at first concerned with how it would machine and approached that part of the construction with trepidation. It turned out that graphite is really nice to machine. It's some pretty tough stuff, although I was taking pretty shallow cuts cuz I didn't want to find out what its breaking point was. The only problem I can see with it is the mess it makes. Toward the end I was holding the shop vac up near the tool to try to suck up all the dust it was making. To answer your question, just about any tool will cut it - even your fingernail. It's is real easy to size because you can use sandpaper to cut it down quickly and then typing paper to bring it to final size. Just think of it as a huge pencil lead. It's really a joy to play with. Try it out. Tom Nance Corpus Christi, TX ------- Date: Mon, 06 Jan 2003 10:46:43 -0800 From: "Orrin B. Iseminger" Subject: Re: Machining Solid Carbon Rods I machine graphite, regularly, with no problems. I use a HSS tool and run the lathe at high speed. Graphite makes a mess and the binder is very abrasive, so I hold the vacuum cleaner suction next to the cutting tool, continuously. The binder will dull the tool, rapidly. You'll need to sharpen it much more often than you'd have to when cutting mild steel. I place cut-up file folder material between the graphite and chuck jaws. I just cut a strip that's long enough to wrap around the whole piece. So far, I've never broken any graphite when machining it. Orrin ------- Date: Tue, 07 Jan 2003 09:39:56 +1100 From: "Charlie Lear" Subject: Re: Machining Solid Carbon Rods Paul Smith" wrote: >Does anyone have any experience in machining carbon/graphite rod? Paul, in my youth I looked at buying a big old lathe that came with a contract to machine electrodes for a steel mill blast furnace. The tool used was a standard brass round nose - zero rake - and SFPM was about the same as for mild steel. Thats about as much as I can recall. I suggest you experiment with the same parameters - it'll only cost you grinding time for one end of an HSS blank and some scrap material. I also played with the rods contained in old D-size batteries - whether they are the same material these days I don't know. But the graphite is quite brittle and you should make a split bush to hold it, rather than straight in the 3-jaw. Set up a vacuum cleaner nozzle close to the action (trust me on this). Cheers Charlie (PS - my dad took one look at the condition of the workshop and the guy selling the lathe, and vetoed it.) 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: Sun, 9 Mar 2003 21:48:03 EST From: catboat15x~xxaol.com Subject: Re: Re: Tapping PVC metalmugerx~xxyahoo.com writes: > Anyone know if you can tap pvc piping for threads? Thanks in advance. Manufacturers of PVC pipe say you should not tap or thread schedule 40, but schedule 80 has much heavier wall and can be threaded. I have both threaded and tapped PVC but take it slow and the chip is long and stringy. Flood with soapy water too it is easy to overheat the plastic. If you examine factory molded threads on PVC fittings you will see a rounded crest and root. Most plastics are notch sensitive (I.E. Potato chip bags, can't tear them, but cut a just a little and they tear right across.) I have threaded and tapped PVC pipe, but not in any critical areas. Tap one piece and die cut another and screw them together moderately tight and they will soon seem like one piece since the plastic seems to "flow" under pressure and self weld. ------- Date: Tue, 1 Apr 2003 16:04:41 -0800 (PST) From: Pete Brown Subject: Problem milling plastic - any ideas? I am milling some plastic rounds on my mill using very thin end mills. I'm basically making a die of a spoked HO-scale locomotive wheel. The problem I've had so far, is that the plastic (UHMW and ABS, both seem to have the same thing going on) both have "peels" at the edges of the part. It's hard for me to explain, but basically when I'm done milling the slot that would eventually be a spoke, there is very thin plastic hanging out the end of the slot and also protruding from the top of the slot. The thin plastic is still attached to the piece, and is difficult to remove without screwing up the part. Is this normal for plastic milling, or am I doing something wrong? Keep in mind I'm very new to this, so make no assumptions :-) I'm following the example set in the Dec? 1998 issue of Mainline Modeler where the modeler did exactly what I am trying to do. No mention was made of the "peelings". I'm open to any suggestions! :-) Thanks. Pete p.s. I forgot to add that the end mills I am using are resharpened wire-size carbide end mills from drillbit city. They appear to be sharp. ------- Date: Tue, 01 Apr 2003 20:39:36 -0500 From: Daniel Munoz Subject: Re: Problem milling plastic - any ideas? Some climb milling (a second pass in the opposite direction) should get rid of most the "peels". I also had this problem with UHMW. I don't know if a cutting fluid could help. I think is it basically because that kind of plastic is very soft and "elastic". Couldn't you use a harder plastic, like Acrylic (plexiglass)? I had some good result with it, using VARSOL (paint thinner) as a cutting fluid. Look here: http://www.nutsnbits.com/acrylic_tank_wheels.htm > I'm following the example set in the Dec? 1998 issue of Mainline I don't know this article, but are you sure the modeler was using UHMW or ABS? Cheers. Daniel http://www.nutsnbits.com ------- Date: Tue, 1 Apr 2003 20:43:48 EST From: wlindiii53x~xxaol.com Subject: Re: Problem milling plastic - any ideas? I machine a lot of UHMW for work not hobby...and what you describe is very typical milling operations. In turning operations, UHMW will make virtually an endless shaving if allowed too...but that toughness is also what makes it a great material for many applications. I am not as familiar with ABS so can't help there. I might suggest trying Delrin rod stock if possible which should greatly reduce the burring on the edges you describe. Basically you aren't doing anything wrong in my opinion, just the property of the material being used. Hope this helps Bill ------- Date: Tue, 1 Apr 2003 18:05:16 -0800 (PST) From: Pete Brown Subject: Re: Problem milling plastic - any ideas? The article specifically mentioned ABS, but it looked more white (might have just been because of the camera flash) Someone else mentioned acrylic off-list. I think it might be worth trying for this type of work. Any problems with splintering or cracking? Do you mill the acrylic like aluminum or ...? Thanks. Pete ------- Date: Tue, 01 Apr 2003 21:13:04 -0500 From: Daniel Munoz Subject: Re: Problem milling plastic - any ideas? >Any problems with splintering or cracking? Do you mill the acrylic >like aluminum or ...? Yes, just as brass or aluminium, with slow rotating speed. Not too fast or the heat from friction will melt it. But it is brittle, so you must be careful with very thin pieces. If it start melting, stop the machining immediately or you'll have difficulties to removed the melted acrylic from the end mill. Guess how I know that :-) My advice is you have choice is to use brass instead for tiny parts... it's so nice and easy to machine. Daniel http://www.nutsnbits.com ------- Date: Tue, 1 Apr 2003 20:58:00 -0800 From: "Marcus & Eva" Subject: Re: Problem milling plastic - any ideas? Hi Pete: Get yourself some Delrin barstock. UHMW is very difficult to machine cleanly. ABS is a bit better, but will burr easily and tends to melt. It's also not very strong. Delrin is beautiful to machine and finishes like glass with sharp cutters. Its only drawback is that it's almost impossible to glue. Cheers Marcus ------- Date: Tue, 1 Apr 2003 23:16:44 EST From: catboat15x~xxaol.com Subject: Re: Problem milling plastic - any ideas? You may be melting some of the plastic with the heat from cutting. Can you flood the work space with water without ruining your mill? Or a jet of compressed air is sometimes used for cooling. John in the high desert of California 12 inch Atlas Mini Mill Rusty file ------- Date: Tue, 1 Apr 2003 23:25:47 -0600 From: "mwhirailer" Subject: Re: Problem milling plastic - any ideas? Has anyone mentioned slowing down the cutter speed? Terry Wellman St. Charles, IL ------- Date: Wed, 2 Apr 2003 09:22:35 +0200 From: Roger Jonsson LINE AUDIO Subject: Re: Problem milling plastic - any ideas? You need a very sharp tool to reduce (what would direct translate from Swedish as) cutting-beard :). I use a precision 3mm (1/8") tungsten/carbide (I think) 2 flute endmill, the same I use for aluminium. Climb milling helps reducing "cutting-beard" as well and gives a perfect finish. If you can use another plastic, try Poly-acetal plastic (POM), it's a marvelous plastic, like cutting butter yet the plastic is very strong, tough and you can get excellent finish and precision AND no "cutting-beard" what so ever. My cuts are usually 5mm (1/5") deep and the feed is up to 4mm/s (1/6" / s = 9" / minute)! Maybe a little slower when climb milling. I also cut Poly-ethene (PE), it's a cheap very soft plastic. It cuts easilly, but I can't get rid of the cutting beard. Now you have read "cutting beard" four times. Sorry five, now. Hope you had fun! ;-) All the best, Roger Jönsson. Line Audio Design tel +46 44 22 54 96 Åhusvägen 74 fax +46 44 22 54 20 291 76 Rinkaby email: rogerx~xxlineaudio.se Sweden http://www.lineaudio.se ------- Date: Wed, 2 Apr 2003 07:31:58 -0800 (PST) From: Pete Brown Subject: Re: Problem milling plastic - any ideas? Thanks. I tried some Delrin and had similar results with the burrs. In fact, last night I quickly tried Delrin, ABS and UHMW and all had similar burring. I'll have to do a more involved test, however. Someone mentioned it might be melting. On inspection, it didn't look melted, however. I'll slow it way down and see what I get for results. Pete ------- Date: Wed, 2 Apr 2003 09:24:36 -0800 From: "Marcus & Eva" Subject: Re: Problem milling plastic - any ideas? Hi Pete: If you can't get good results in Delrin, then your cutters are not behaving properly. If they are reground, you've probably not got enough side relief on the flutes. Buy yourself one brand new Niagara cutter in the size you need and try that. You should get a silky smooth surface with no burs at all. Cheers Marcus ------- Date: Wed, 2 Apr 2003 22:55:56 +0100 From: "Andrew S Knox" Subject: RE: Digest Number 1093 Try http://www.polymerprocessing.com/polymers/POM.html Short but sweet, DuPonts Delrin, as already mentioned. I quite like polycarbonate, even with quite slow and small feeds it cuts clean, but if too small a cut of fast a spindle speed you can get the swarf to weld if this is the bearding your on about (interesting term...) Regards Andrew ------- Date: Wed, 2 Apr 2003 18:12:02 -0800 (PST) From: Pete Brown Subject: Re: Re: Problem milling plastic - any ideas? I did a quick unscientific test today. THe UHMW burrs (beards? ) at even slow spindle speed and feed. The ABS does as well, but not as much. The delrin, which burred at high speed, seemed pretty clean at low speed. I'll play around with it some more later this week. Pete My Personal Site: http://www.IrritatedVowel.com ------- Date: Thu, 03 Apr 2003 05:26:25 -0000 From: "jlupher2" Subject: Feed rates on foam Hello everyone. I just got a Taig mill, the 2017LE, day before yesterday, and I've have to say that it is just plain fun. I have only slept about six hours since I got it! We are using it to make prototype parts for product development. The parts are usually made via SLA and then tooled for injection molding. So, I am trying to figure out the optimal use of the Taig for prototyping. My guess is we will end up cutting foam, or modeling board for development work, and then make a working prototype out of the material the production product would use (ABS or PC or PP). Our goal is to cut parts faster and cheaper than our typical (outsourced) SLA turn. BTW, I am a veritable newbie when it comes to CNC, but I am learning a lot lately! Questions: When cutting foam, what feed rates can I reliably use? The foam is nothing to cut, but the steppers can only go so fast? When cutting harder stuff, it seems likes a cutting strategy is the key to getting a part done quickly. How many different end mills are people using when cutting blocks of plastic or modeling board? I have been using Deskproto, but does it pay to get a more advanced toolpath generator package? Is simulation of the toolpath essential? Nice to have? Thanks in advance for any help. John ------- Date: Thu, 3 Apr 2003 08:38:56 -0500 From: "Carol & Jerry Jankura" Subject: RE: Feed rates on foam Hi, John: Your questions are not specific to Taig products, so here's what I'm doing with a Sherline CNC mill. Everything should be applicable to you. When setting up your CNC system, you'll have to set up parameters such as acceleration, maximum velocity, etc. The goal here is to make your machine rapid moves as fast as possible without losing steps. How do you tell if you're losing steps - well, the motors may very well stall out. Or, if you have double ended motors with a knob on the back end, just touch the knob a little and you'll feel the stutter in an otherwise smooth rotation. Since every mill is different, expecially after you adjust gibs, etc. you'll have to experiment with this on your own. I've worked with my machine's parameters until the motor was performing just below its stalling point. Then, I backed off of the maximum velocity by about 10-20%. Also, you'll have to test each axis separately, as the parameters will probably be different for each. I'd suggest that you join yet another list on Yahoo - CAD_CAM_EDM_DRO. It's sole purpose in life is to help folks set up and use CNC in a 'home' environment. The questions that you've posed here fit directly into that charter, whether you're a 'home machinist' or not. Jerry ------- Date: Mon, 16 Jun 2003 17:51:22 -0000 From: "Charles Hixon" Subject: Re: turning wood with sherline lathe [THIS THREAD CHANGED SUDDENLY INTO A PLASTICS DISCUSSION] You might avoid composites like glass-fiber reinforced polyester (fiberglass) because the glass fiber is silica and turns into sandpaper-type grit as you fracture the fiber during machining. Paper-, Cotton-, and Carbon-reinforced composites may not be as bad. Probably the easiest way to determine which fiber you have is to look at their fractures under a microscope. Plastic manufacturers generally have a machinability rating for their grades of plastic. Some of them list their rating on the internet. The problem is often identifying what plastic you have and you want to get this up front. If you buy analytical Fourier- Transform Infrared Anaylysis service to identify it, you will more often than not narrow it down to a few possibilities. Those possibilities can be eliminated or supported by individual thermal or chemical tests, depending on what you've narrowed it down to. Then it's a matter of sifting through various manufacturer's listings to try to determine if they offer it and what their trade name is for it. When you have that determination, you have a listing of properties, including machinability. Also avoid glass-fiber reinforced melimine. You might know this as the green or brown PC circuit board material. Excellent material, but you're machining sand when you hit the glass. Throw that sand into your aluminum ways and you've got a loosy-goosy mill. Charles ------- Date: Mon, 16 Jun 2003 21:03:17 -0300 From: "Neil Albert" Subject: RE: Re: machining plastic with sherline Charles: Does this mean my plans to machine some PCB patterns on my Sherline definitely out? Do you know if there are blank PCB's made with a substrate other than glass-fiber reinforced melamine that would be safe to use on the Sherline? Neil ------- Date: Tue, 17 Jun 2003 02:27:04 -0000 From: "Charles Hixon" Subject: Re: machining plastic with sherline Neil: You can't beat melamine for abrasion resistance, strength, dielectric properties and flame resistance. There's no substitute IMO. Glass fiber is used as much as a reinforcement material as it is a filler. It's the glass fiber that's the problem, not the melamine resin. The nearest alternatives might include whatever varieties of polymers are used for distributor caps for instance, but at least some of these are fiber-reinforced - I don't know the varieties - nor the types of fiber used as filler. Maybe they're all melamine with glass too. Before melamine, there was rubber, hard rubber and Bakelite. That's what my 80 year old fire truck is equipped with. I don't know the PCB business: you gotta do what you gotta do, but I'm keeping my mill out of the sandbox. Too bad you couldn't use some type of small CNC overhead gantry device. All I can think of is the obvious: shield your slides and collect and contain the residue ASAP, maybe with a vacuum cleaner turned on and attached to the spindle housing, disassemble, clean and re-grease your slides often. Charles ------ Date: Mon, 16 Jun 2003 19:39:26 -0700 From: "Dave Hylands" Subject: RE: Re: machining plastic with sherline Hi Neil, I haven't used these myself, but I've heard that you can get phenolic substrate on PCBs, which is much more cutter friendly than fiberglass. There is a Yahoo group with lots of good links to suppliers and such: http://groups.yahoo.com/group/Homebrew_PCBs/ (click on the Links area) Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Tue, 17 Jun 2003 02:47:21 -0000 From: "Charles Hixon" Subject: Re: machining plastic with sherline Yea, Bakelite is a phenolic, lots of different kinds of phenolics around. Not as good as melamine, but a step up from hard rubber. I like to turn replacment knobs out of phenolic blanks. Charles ------- Date: Tue, 17 Jun 2003 00:28:31 -0400 From: "Statman Designs, LLC" Subject: Re: Re: machining plastic with sherline Neil: I have no experience machining PCBs on anything. I do know that the Sherline machines can take an amazing amount of abuse. I have abused my long-bed lathe for 5 1/2 years machining only grade-5 titanium. After machining I then sand and polish the pieces while spinning on the lathe with emery cloth and jeweler's rouge. I am sure that everyone here will tell you not to grind or polish over the bed ways. It is just a matter of the level of convenience that you desire. I view my Sherline's (2 lathes and 3 mills) as completely and totally disposable. If it wears out or breaks, every single part is available individually directly from Sherline and can be delivered overnight. I have replaced nearly every part on my long lathe and one of the milling machines, and many of them more than once. I can tear the entire machine apart and re-assemble it in about 1 1/2 hours (or less). If you need to cut PCBs, then I say just do it and deal with the wear items as they develop slop. Of course, I make money with my machines, so it is definitely NOT a hobby for me. Daniel J. Statman, Statman Designs www.statmandesigns.com dan.statmanx~xxrennlist.com ------- Date: Mon, 16 Jun 2003 23:54:32 -0500 From: Ron Roske Subject: Re: Re: machining plastic with sherline Neil: Lots of phenolic boards out there to chose from. Single sided, dbbl sided, various thickness. Should work well for what you are planning on doing. The thicker stuff won't flex as much as the thinner and probably would be more applicable for your purposes. Radio Shack carries some and other electronic supplies will have them, too. Best of luck on your proposed projects and let us know how they come out. RonR ------- Date: Tue, 17 Jun 2003 10:42:30 +0200 From: Roger Jonsson LINE AUDIO Subject: Re: machining plastic with sherline There are special endmills for glass-fibre PCBs. I use them frequently. Milling PCBs is 100% problem free and the result is rater good, using these endmills. Cuts very easily. I don't know the original source, I buy them from Solectro www.solectro.se , here in Sweden. They also carry good tungsten-carbide PCB drills as well sa PCBs and machinery. All the best /Roger Jönsson ------- Date: Tue, 17 Jun 2003 10:46:12 -0700 From: Alan Marconett KM6VV Subject: Re: Re: machining plastic with sherline Hi Neil: There is a home-brew PCB list on yahoo you might check out: Homebrew_PCBsx~xxyahoogroups.com The light brown phenolic boards are "soft", and can easily be milled. The swarf won't harm the ways. Also, the swarf can be contained. Put a temporary cover over the ways. A 1/2" hose plumbed up to a vacuum cleaner will keep it picked up. It usually just piles up on the PCB, anyway. About the only real problem is the short life of cutters! Use carbide if possible. A few boards won't hurt much. John Kleinbauer's site gives some info also: http://www.kleinbauer.com/ DeskCNC and DeskPCB programs (IMService) can handle Gerber files for milling. Eagle has a PCB layout program (some free) that is great! http://www.cadsoftusa.com/ HTH Alan KM6VV SherlineCNC ------- Date: Tue, 24 Jun 2003 22:00:15 -0000 From: "variousgroups" Subject: Delrin (acetal) in Colors Anyone? Does anyone know of a source for Delrin (acetal) bar stock in colors? Black and white I've got plenty of, I'd like some red, yellow, blue, green, the basic colors. I need a cross section at least 1.25 x 1.5 inches. Mike ------- Date: Tue, 24 Jun 2003 17:55:12 -0500 From: "mwhirailer" Subject: Re: Delrin (acetal) in Colors Anyone? Mike: I would try TAP Plastics. They're on the web and supply a lot of plastic including Delrin. That's where I get mine from. They have several distribution points throughout the country. Terry Wellman St. Charles, IL ------- Date: Sat, 28 Jun 2003 14:07:27 -0000 From: "variousgroups" Subject: Colored Acetal (Delrin) - Source For Only one company I've contacted thus far offers colored acetal (Delrin ®: Modern Plastics in Bridgeport, Connecticut. I sent an email inquiry to each of several firms for bar stock with a minimum cross-section of 1.5 square inches. Here's the reply from Modern: "Thank you for your inquiry - "As a standard item, colored Delrin acetal products are not available. However, we do stock a number of rod materials in acetal copolymer (a very similar product to Delrin)in sizes from 1.500" to 3.000". Perhaps you could use the rod instead. The rod is typically used for "medical" type applications, but we have found that customers who want to have colored Delrin without having to pay for large minimum runs, this was an alternative. "The rod closest to your request would be colored medical grade acetal 2.500 diameter, Blue, black, green, and yellow are currently available x~xx 54.40 /ft. lengths are 4 feet long. Please let me if you would like to order." David A. Altieri - V.P. Sales and Marketing Modern Plastics, Inc. 678 Howard Avenue, Bridgeport, Connecticut 06605-0574 203 333-3128 - Extension 207 800 243-9696 - National Toll-Free Line 203 333-4625 - Fax Number www.modernplastics.com Best, Mike ------- Date: Wed, 06 Aug 2003 00:37:20 -0000 From: "jchrisj7734" Subject: Re: cutting carbon fiber plate > Anything with carbon fiber in it is going to be highly abrasive. > Where I work we use diamond saws and carbide to machine carbonfiber > composites. If your plate is a laminate, be extra careful about > creating disbonds at the interfaces. Keep it slow and the cuts light > and you should be OK. Also, we cut everything wet to keep things > cool and to keep the dust under control. HTH, Mac We cut carbon fiber reinforced polymer composite panels with a wet cutting diamond saw at work. One thing to keep in mind is that carbon fiber is electrically conductive so you really want to control the dust. We had a series of computer power supply failures in our processing lab where carbon fiber dust was a strong suspect. Using an extender box to keep the monitors, mice, and keyboards in the lab and the computers in a more protected environment settled the problem down. You don't appear to need long pieces of fiber to cause those problems, the dust is enough. You probably don't want to breathe the stuff, either. ------- Date: Wed, 06 Aug 2003 00:50:07 -0000 From: "Gary Severson" Subject: Re: cutting carbon fiber plate I do a little hobby laminating and I use a carbide dremel bit that is labeled as a tile cutting bit for triming the flash off if that is your intended use. Gary Severson ------- NOTE TO FILE: Various subjects during July-October 2003 in the Metal_Shapers group contained info on how we might make a replacement gear for the Phenolic bull gear used in an AMMCO shaper; those are reported in the AMMCO Shaper text file and may be useful to others faced with making special gears or otherwise working with Phenolic materials (resin-cloth laminates available under many names). ------- Date: Sun, 19 Oct 2003 21:31:51 -0000 From: "Art Volz" Subject: Military Standards for Phenolic Resin Fabric Laminates I have researched current US Army files today and have found the Military Standards that apply to Phenolic Resin Fabric Lamininates. The Military Standard that provides general specifications is MIL-I- 24768, dtd 25 Feb 92, and entitled: Military Specifications-- Insulation, Plastics, Laminated, Thermosetting, General Specifications For": http://assist.daps.dla.mil/docimages/0000/95/07/24768.PD1 . At paragraph 1.21.a "Cotton Fabric Base, Phenolic-Resin Binder" it lists four such plastics for possible consideration as cut gears: --FBE--Electrical Grade --FBG--General Purpose --FBI--Machining Applications --FBM--Mechanical Grade In Table XXIII "Cross-Reference Guide For Laminates" are provided the Industrial Designations for the military ones: --L = FBI --LE = FBE --CE = FBG --C = FBM http://mcmaster.com carries in stock phenolic laminates in these four industrial designations. For gears, the finer weave L and LE grades are probably the ones to use. In this regard, I have today "won" an auction for a 14-inch x 24-inch x 1-inch thick slab of LE grade with which I and Mike F. will conduct gear cutting experiments--hopefully successfully--commencing with the attempt to cut a 10-inch OD bull gear wheel for a Lewis with a DP of 8. Specific Military Standard specifications for these four grades of phenolic laminates are at: FBE: MIL-I-24768/13 -- -- http://assist.daps.dla.mil/docimages/0000/21/86/106225.PD9 FBG: MIL-I-24768/14 -- -- http://assist.daps.dla.mil/docimages/0000/21/87/106226.PD0 FBI: MIL-I-24768/15 -- -- http://assist.daps.dla.mil/docimages/0000/21/87/106227.PD1 FBM: MIL-I-24768/16 -- -- http://assist.daps.dla.mil/docimages/0000/21/87/106228.PD2 I have only conducted a rapid scan of these Mil Specs but didn't immediately see any specific information on machining. I do have general machining data for phenolics in my "Machining Data Handbook" from which I will extract some starting cutting data--tool type, feed, speed, and DOC--and post here sometime later this week, as time permits...and Yahoo obliges. Art (Houston North) I have posted spec sheets for Garolite CE and LE Grades (from McMaster catalog) in a "File" titled "Phenolic Laminates" at http://www.groups.yahoo.com/group/Metal_Shapers_Pix . ------- Date: Mon, 17 Nov 2003 07:49:44 -0000 From: "mileagemayvary" Subject: Re: 2 flute mill sucks more? In sherlinex~xxyahoogroups.com, "neilalbert2001" wrote: > I am machining a plastic part whose bottom is a fairly thin horizontal > plastic surface, and I am concerned that this section will lift as it > is being machined Can be quite a problem. The thing I have found in this situation, depending on the plastic type, is to keep the heat down to avoid warping deformation. A very sharp tool, fast feed, and turning the speed down. The hold down tape should be a help but could be counterproductive by insulating the heatsinking of the table. ------- Date: Tue, 13 Jan 2004 22:45:58 -0000 From: "Lee Owens" Subject: Looking for **small** amounts of acrylic and teflon rod The local supply shops don't have rod in the scrap pile. I need acrylic for making model car parts like tranmissions, rims, oil filters, etc. Buying 12feet at a time would get me 5 lifetime supplies. Can anyone spare a foot or so of various diameters of acrylic, lexan, or teflon? I'd be happy to pay for it. I just don't need 12 feet of each. Looking for 1/2inch up to about 3 inches. Thanks, Lee ------- Date: Tue, 13 Jan 2004 23:45:52 -0000 From: "Jim Knighton" Subject: Re: Looking for **small** amounts of acrylic and teflon rod Lee, I don't have a complete solution for you, but you might look in outfits that sell pen making supplies. Last weekend I was in the local Woodcraft store and picked up some phenolic resin blanks - not for making pens, but as blank stock for other projects. The stuff might be ugly, but you're probably going to paint it anyway. The stuff I got was about 6" long, 3/4" diameter and also some blanks roughly 1.5" diameter x maybe 2 or 3" long. Also, McMaster-Carr sells some industrial plastics by the foot. Several months ago I got a 2' length of delrin from them. I hope this helps. Jim Knighton ------- Date: Tue, 13 Jan 2004 18:58:57 -0800 (PST) From: Scott Meyer Subject: Re: Looking for **small** amounts of acrylic and teflon rod Try McMaster-Carr at www.mcmaster.com. They have all kinds of "industrial" materials inlcuding teflon, acrylic, and I imagine Lexan and the others you mention. You also might try www.onlinemetals.com. They have lots of different metals, but also teflon, delrin, some acrylic, etc. They do specialize is small orders, and cater to the hobbiest quantities. I have used Online Metals, and like them alot. I have not used McMaster in years, but never had a problem with them. Scott ------- Date: Wed, 14 Jan 2004 18:49:52 +1200 From: "Richard T. Perry" Subject: Delrin, etc... I don't use the stuff much myself, but when I have, I've gotten it from Small Parts in FL (try www.smallparts.com) We just got a bunch at work to (re)make some rollers for the side doors in the UH-1 helicopters we service here. Smallparts isn't the cheapest place in the world, pound for pound, but when you only NEED a pound..that's who I go to. A quick browse through their catalog shows about 6 different plastic types in various diameters up to a couple of inches in 3" to 36" lengths. Also, I got a really nice "grab bag" of UHMW plastic blocks from Woodcraft a few months back (I was making a jig.) 3 pounds for $10, p/n 143291. Really nice stuff - feels like teflon, machines like aluminum (but use carbide bits, not HSS, like the instructions say... I proved that one the hard way). Good luck! Regards, Richard T. Perry ------- Date: Wed, 14 Jan 2004 09:48:43 -0500 From: "Mike DeMetz" Subject: Re: Looking for **small** amounts of acrylic and teflon rod MSC(www.mscdirect.com) sells plastic rod in 1 ft lengths. ------- Date: Wed, 14 Jan 2004 15:25:54 -0000 From: "Kevin Williams" Subject: Re: Looking for **small** amounts of acrylic and teflon rod This may not help for "small" quantities, but one of the best suplliers of plastics I have found is Ridout Plastics - http://www.ecomplastics.com/index.html . They have just about every type of plastic in a variety of shapes (rod, tubes, plates etc) and size, plus the proper adhesives and even tools for cutting plexiglass. For acrylic they have both cast and extruded shapes, cast acrylic machines much better than extruded acrylic. Their website has lots of good info about plastics, including machining characteristics. They will ship small amounts of most items, but the catch is is they have a minimum $100 order. So, for example, they will sell you 1 foot of 1" black Delrin for $4.39 plus shipping, but you will have to put together an order of $100 to get anything. I have placed orders with them in which the $100 minimum was composed of a half dozen different sized items. Kevin ------- Date: Wed, 14 Jan 2004 16:12:55 -0000 From: "Bryan Hassing" Subject: Re: Looking for **small** amounts of acrylic and teflon rod Hi Lee: I build 1:24 scale model big rigs. I use my Sherline long bed lathe, occasionally equipped with a vertical milling column and rotary table, to make parts like those you mentioned. While I buy my Evergreen Scale Models or Plastruct sheet products from local hobby shops, I get all my plastic rod from McMaster-Carr (http://www.mcmaster.com). I use their beige ABS rod which cuts like butter using standard Sherline 1/4" HSS lathe tools. I have made various size truck tires on the lathe and really like the glass- smooth finish I get from the ABS rod. A side benefit of using ABS is that it is easily sanded and painted. McMaster-Carr sells 0.250", 0.375", 0.500", 0.625", and 0.750" diameter ABS rod in 5-foot lengths only, but the larger diameter ABS rod is sold in 1-foot increments. The 5-foot length materials show up in a nice, sturdy four-inch mailing tube with end caps, which is what I use to store the spare material. While I also don't need five-foot lengths of these materials, at least I can experiment all I want and never fear running out of stock. I don't McMaster has a minimum order requirement. I did a quick check between McMaster and MSC Direct and found that the ABS rod is about 30% cheaper than acrylic in diameters up to about 1". The cast acrylic rod is about 30% cheaper than ABS once you get up to the large diameters like the 3" you mentioned. MSC will sell the small diameter ABS rod in 1-foot increments too and is slightly less expensive than McMaster. Hope this helps. Bryan ------- Date: Thu, 05 Feb 2004 18:14:30 -0000 From: "Brian Chapman" Subject: Flycutter question I'm working with various sizes of ABS plastic sheet. At the moment, .080"; as with all plastic sheet I've used so far, the ABS varies a couple of mils in thickness from one spot to another. I used the flycutter for the first time just now; it left ridges from one row to another. Might this mean my attempts at squaring the Sherline 2000 mill needs work (wish I had not bought the 8-axis model); what can I do to correct the problem? Sure appreciate any help with this I can get. Thanks much, Brian Chapman Cedar Rapids, Iowa ------- Date: Thu, 05 Feb 2004 18:50:06 -0000 From: "mc_n_g" Subject: Re: Flycutter question If you can not cut the whole width at once with a flycutter, it is very hard to not get small ridges. Without an extremely balanced flycutter and heavy mill you will never get a truly flat surface with flycutters. There are a lot of forces acting on the mill when you use a flycutter and the head must be very stable. Read the study in flycutter design a month or so ago in the Homeshop Machinist. There is a lot of good information. You may also be having problems with a wrong cutting rake angle. Not having a long smooth radius on the cutter.... That is a whole different ball of wax. mc_n_g ------- Date: Sat, 7 Feb 2004 14:15:29 -0800 (PST) From: Jim Izzolo Subject: Re: Tapping plexiglass witstock7 wrote: >>>I need to tap some 6-32 holes in 1/4 inch plexiglass and can't find any info on what to use as lubricant. Any suggestions appreciated. Nelson>>> I may be wrong but I think water with a little bit of oil works. You also need a bit that is made for drilling through plexiglass. It has a different angle than metal or wood bits. Sorry I cant help you more, but I am sure others will know more than I do about this and I will learn from them as well as you. Jim ------- Date: Sat, 7 Feb 2004 15:33:54 -0800 From: "Dave Goodfellow" Subject: RE: Tapping plexiglass I tapped smaller holes (4-40) in the plexiglass cylinder block of my I Spy engine, with no lubricant at all. The plexiglass does want to grip the tap, so I needed to back out often. Also, once I was at depth I needed to run the tap back and forth several times to open it up enough to get the screw started. The tapped hole had some resistance to accepting the screw, but for my purposes that was a good thing; the screw would not back out under vibration. I've been told (don't know from experience) that any of the oil-based tapping fluids will damage the plexiglass. If I really needed to use some lubricant, I'd try Crisco or butter -- or maybe some vegetable oil. Experiement with some scrap plexiglass and see what they do before using it on your workpiece. Dave Goodfellow Lancaster, CA http://www.davegoodfellow.com/ ------- Date: Sat, 7 Feb 2004 23:32:58 -0000 From: "Nelson Wittstock" Subject: Re: Tapping plexiglass I did a dry tap on a scrap piece and had no problems but just wanted to make sure that there isn't a better way before I do the "real" pieces. These will be drilled almost all the way through but not completely and then tapped with a bottoming tap. Thanks for the input. Nelson ------- Date: Sun, 8 Feb 2004 01:20:30 +0100 From: Pavel Koøenský Subject: RE: Tapping plexiglass I am using normal HSS drill bits and normal taps. Everything works OK, if you put a bit of water on them. Or simply, spit on them. The main problem with plexiglass is temperature. If the temperature is low enough and the glass does not melt, everything is OK. Best regards PavelK ------- Date: Sun, 08 Feb 2004 00:46:59 -0000 From: "Radish" Subject: Re: Tapping plexiglass If you get hold of an OLDER drilling and tapping chart, you will find mentioned on this chart that PARRAFIN can be used as a tapping or drilling agent. If you check out what is mixed in the newer formulas for tapping and drilling, you will find that parraffin is part of the make-up of these newer agents. So why not by bypass this newer stuff and use one of the original agents, by the way, this stuff works wonderfully well and it sure is a lot cheaper than these newer mixes. This stuff is recomended to be used on copper and brass so it sure is slippery, I use it on everything, steel, brass, aluminium and even acrylic/plexi-glass, you can even see the thread being formed when you use it on clear acrylic/plexiglass. No damage what so-ever when you use it on any of the above. You can buy this liquid parrafin at any chemist/drugstore, it is still used as a laxative, so if your job is giving you the sh*ts, take a swig of your tapping agent and you too can have the sh*ts. radish ------- Date: Mon, 16 Feb 2004 13:15:16 -0000 From: "chimpygoo" Subject: Re: Plastic recommendation and speed control In taigtoolsx~xxyahoogroups.com, "ejbardet" wrote: > I am just getting started in building some scale shop tools (1:24 > scale) for a 1900 era facility and I have a few questions. > 1- Which is the best plastic to use? I know styrene is quite > popular, but I was wondering about machinability. ed, there really are no best plastics for all app's, but i can tell you this: machinability of styrene is pretty bad - unless you have a specific reason to use it, such as cost or color, there are many easier plastics for a novice to machine. --acetal/delrin-- by far the best all around machining plastic, but can be very expensive unless you can get it surplus. ---pvc/cpvc-- good machining , moderate cost, can get surplus at good prices. ---hdpe/marineboard/starboard-- recently there's been a ton of this stuff on ebay- machines incredibly easy ,fairly strong, and can sell unbelievably cheaper than just about anything else. ----nylon and polypropylene-- also available fairly cheap, but more challenging to machine...tends to grab large drills(esp p/pro) > 2- What I have read indicate that slow speeds and heavy cuts are the > secret to working with plastics. Are the slowest speeds available on > the mill and lathe appropriate or do I need a speed reducer? If I do > where can I get one? might want to brush up on some basic machining practice,i.e. feeds and speeds..to start with..the appropriate speed rpm has everything to do with the diameter of the workpiece(lathe), or dia. of the cutter(mill) to arrive at the working SFM(surface feet/minute)which is appropriate for that material. sfm=(cuttingspeed x 4)/ dia of part or cutter. but.. in practice, esp without coolant, plastics don't behave like metals- metals wick the heat into the part, platics tend to "insulate" the tool and capture the heat= you'll want to use heavier feeds to keep tools from melting the plastics. so... in pvc , for example, i might turn a 1" diameter at 900rpm and a 1/4" piece at 3000 rpms. ...but if i were to run a 1/4" drill into pvc at 3k , say 1" deep w/out coolant i'd soon have a gooey mess melted all over the drill...probably run that .25 drill at about 900rpm. on the lathe the tool won't generate nearly as much heat because the area of contact/insulation is much smaller =much faster rpm's. won't melt everything as fast. makes no sense , right ? welcome to plastics. get some scraps and practice-make notes of what works and what doesn't. use carbide tools if you can-plastic can be very abrasive and can dull high speed tools faster than steel. i've been machining pastics in production for 15 years....the only way to figure it out is trial and error. > 3- Any good books on working with plastic? > 4- Is there an on line source of correct FPM numbers for the various > plastics? the various mfg's ( G.E. , Dupont, 3M,etc..) have charts and thingies with reccomendations and such, but i've always found them less than useful---might be a good place to start though. good luck Ed ------- Date: Mon, 16 Feb 2004 09:57:29 -1000 (HST) From: Tom Benedict Subject: Re: Re: Plastic Recommenation > Do these scale shop tools have to be in plastic? Personally, I would > consider using brass - it is very easy to machine. Alan Smith Lemme second that. Brass is an absolute blast to machine. I've been told aluminum bronze is equally fun to cut, though I haven't had the opportunity to try this. A while back I was griping about copper, and was told that there are nice copper alloys for machining. I accidentally ran across one while making some parts for work. The thing started life as a big honkin' grounding bar for a power grid. It's about 1/4" thick, 4" wide, and several feet long. The stuff cuts like brass! So there are three materials to try. In the wood department, ebony cuts a lot like brass. It's a strange wood to cut but the machining characteristics are almost a carbon copy of brass. Cast iron is also pretty nice to cut, though the "chips" are basically metal sand. If you put a strong magnet inside a plastic baggie and stick it near where you're cutting, most of the iron chips will cling to the magnet instead of flying around your shop. When you're done, turn the baggie inside out and pull it off the magnet. Voila. Clean magnet and all your chips are in the bag. Honestly from the standpoint of realism as well as from the standpoint of ease of machining, I'd give brass or gray cast iron a try. They're pretty neat and you'd have a fully functional miniature when you're done. Tom ------- Date: Wed, 26 May 2004 02:52:27 -0000 From: "asrpas" Subject: How to part-off many piecs out of long plastic extrusion? Hi, Could someone suggest best way to part-off 1/2" pieces out of long ABS plastic solid rectangular bar, I need to make 200 pcs. Idea is to buy rectangular section and cut the required section profile on the whole length and cut it off into 1/2" pcs, imagine like we make T- Nuts but this section profile is more complex than t-nut.(section is about 1"x2") My question is; Can I use Miter Saw to cut those pieces? I don't have mitersaw so can't try thought better ask before buying. Another point is I need to have good finish after parting off and can't afford to machine each face after parting. Is there any sort of burning or melting on plastic using saw. If I use taig mill to cut off using endmill it'll take forever. I'm open for any suggestion or ideas. Thanks in advance. Regards, Rick ------- Date: Wed, 26 May 2004 04:22:48 -0000 From: "Ed Chesnut" Subject: Re: How to part-off many piecs out of long plastic extrusion? I'm a manufacturer of injection molded ABS control stick grips for small aircraft. Upon reading your question I went to the garage and cut a blemished grip in half on my table saw. The resulting finish was pretty darn good with clean sharp edges and no burr - and no melting. The blade on my saw is 10", about 40 teeth, Alternate Bevel teeth, carbide tipped. The blade could be in better shape since I use it for cut-to-length operations on 1/8" wall Aluminum tubing (6061 T6) AND for cross cut and rip operations on recycled lumber. With a chop saw or miter saw with good bearings x~xx the hinge point and a good sharp blade designed for smooth cutting - I think you'll be happy as a clam. Ed ------- Date: Fri, 6 Aug 2004 12:41:07 -1000 (HST) From: benedictx~xxhawaii.rr.com Subject: Profililng acrylic [taigtools group] I haven't done much in the way of milling with acrylic. Engraving, yes. Turning, yes. Hoggin'out and profiling, no. What's a good combination for profiling acrylic? I can likely rough with a 1/4" or 1/8" mill, but will need to finish with something smaller, say in the 1/32" size. (Metric or Imperial is fine by me. I'm not picky.) The work itself is going to be pretty small, say 1/2" wide by maybe 1" long, probably smaller. Can I use standard end mills or is the geometry too far off that it won't give good results? Surface finish is unfortunately pretty important, though a mirror finish isn't required. But minimal tooling marks would be good. Far as coolant goes, I've got mist coolant, an air jet, or me with a squirt bottle available. For drilling ABS I've had good luck with the air jet, but I'm up for ideas here. Thanks, Tom ------- Date: Fri, 6 Aug 2004 20:43:10 -0700 From: "Felice Luftschein and Nicholas Carter" Subject: Re: Profililng acrylic Travers has single flute solid carbide routers (Micro 100 brand) in their latest sale catalog, down to 1/16" dia. The sales blurb says they have a polished flute and are ideal for plastics. About $15-$20 each.... I hear soapy water works well, I imagine mist would too. The key as I understand acrylic is to avoid heat, and have a sharp tool. Check out our homepage www.cartertools.com/nfhome.html ------- Date: Sun, 08 Aug 2004 00:39:05 -0000 From: "buddyborders" Subject: Re: Profililng acrylic The only problem with soapy water is the cleanup. Kerosene (paraffin) works well for a cutting lube and can also be mixed with sulfer based cutting oils if available. Negative rake tooling, like that used for brass, works well I find. Especially when drilling holes to avoid/minimize breakout on the back side of the part. HTH. Buddy Borders Philadelphia, PA ------- SAFETY WARNING: CUTTING CARBON FIBER products produces extremely hazardous dust and particles. Research the health hazards and employ all industry and OSHA mandated and recommended safety equipment and protective rules and safety measures adequate for your particular situation and work before ever starting! Seriously consider safer alternative materials for your projects, or having a competent professional company do all this dangerous work for you. ------- Date: Wed, 15 Dec 2004 17:50:21 -0700 From: "Doug Powell" <4machiningx~xxcomcast.net> Subject: Re: Cutting Carbon Fiber? [taigtools] Original Message ----- From: dkp_design >> I would like to know if anyone has experience cutting carbon fiber sheet in their mill. If so, what bits and feed speeds did you use? I cut my first piece tonight, it drilled excellent, but frayed when I cut it out. I was using a 2 flute carbide .125" cutter at max speed, 2IPM feed. Any help or suggestions? Carbon Fiber is expensive material to be having a bunch of test pieces. << I cut carbon fiber nearly every day producing parts for RC race cars. I use 3/32" solid carbide up cut circuit board cutting bits and circuit board drills as well. The CF is very abrasive and dulls the cutting bits quickly. I cut at high spindle speed and 10 inches per min. The optimum spindle speed would be about 23k. At that speed the feed could be considerably faster. Contact me off list if you have more questions Doug Powell ------- Date: Wed, 15 Dec 2004 20:22:27 -0000 From: "Dave" Subject: Re: Cutting Carbon Fiber? I was an f-18 mechanic, that whole plane is carbon graphite. You need to use a diamond coated burr. It works more like a rotary file than an end mill. Lots of rpm (20k for a .25 tool) and use plain water to cool and keep the dust down. Drilling use a 60deg pointed bit, similar to an engraving bit with one or 2 flutes. Graphite dust is very bad for your lungs. Remember a graphite splinter works its way into your skin not out like a metal or wood one. ------- Date: Thu, 16 Dec 2004 09:06:34 -0500 From: Ken Jenkins Subject: Re: Cutting Carbon Fiber > So, I would have more luck with a Dremel? I have some drills that > are almost a flat point, they do seem to drill nicely. I have some > rotary file type bits for my dremel. That was my original plan, to > make a template out of alum and use the Dremel to cut it out. That > was until I got my Taig :D You might try using a laminate trimmer to get your high RPMs. A Dremel won't hold up very well. I mounted a Dewalt laminate trimmer in place of my mill spindle using a mount made out of a Taig riser block. It works great for engraving, woods, plastics, etc. You can see it here: http://kj.cloudcitydigital.com/pages/taig_mill_d660mount.html Ken J. ------- Date: Wed, 15 Dec 2004 12:47:58 -0800 From: "Larry Richter" Subject: Re: Re: Cutting Carbon Fiber? > Graphite dust is very bad for your lungs. Remember a graphite splinter > works its way into your skin not out like a metal or wood one. Oh, man. Meaning the fiber splits out of the matrix with a barbed surface on it? That's the nastiest thing I've heard about it. ------- Date: Wed, 14 Dec 2005 21:51:39 -0500 From: Rich Crook Subject: Re: Plastic recommendation [taigtools] At 08:18 PM 12/14/2005, Larry wrote: >I purchased a Taig mill a few weeks ago and also bought many assorted >types of material to practice with and have been really learning a lot >(making swarf mostly). I have successfully machined Delrin, UHMW, >Teflon, ABS, PVC, Acrylic, Polycarbonate but was wondering what would be >the the recommendation of an easily machined plastic that is also >glueable to itself without special equipment. My current candidates are >ABS, PVC, Acrylic, and Polycarbonate but perhaps there is something >better. The material cost is not too important and the color does not >matter. Would the recommendation change if I also wanted the chosen >plastic to be glueable to aluminum or steel? I worked for 10 yrs in an industrial modelmaking & prototyping shop, and we used primarily acrylic plastic (aka Plexiglas or Lucite) to fabricate all kinds of things. Very versatile stuff - it machines easily, can be readily heat-formed and can be solvent welded with liquid model-building cement (methylene chloride.) We would usually hold it down on the machine with thin double-sided tape (*not* the foam type!) & pry it loose with a thin putty knife when done. It takes some practice to learn how much tape is enough without overdoing it. Xylene (aka xylol, a paint solvent) works nicely to help release stubborn tape without damaging the acrylic. (It *will* attack polycarbonate, tho!) Methylene chloride, "two-face" tape and Bondo were absolutely essential supplies in the model shop. This same solvent will also work on styrene, polycarbonate (aka Lexan or "bulletproof" glass), butyrate and ABS, and should be available at any hobby store that sells plastic model kits. I have a 2 oz botle of "Ambroid Pro-Weld" that cost $3.19 at the local hobby shop; 2 oz will last you quite a while. (Just keep it tightly closed - like many solvents, it evaporates quickly.) Acrylic plastic can be either cast or extruded ("extruded" sheet is actually rolled.) Cast stock is more expensive, but machines better, and has an optically clear surface (it's cast between sheets of plate glass.) Extruded is more prone to "gumming up" if it gets too hot while cutting - it partially melts & forms a white crusty surface. One caveat for cast sheet - the surfaces are optically flat, but it usually won't be quite uniform in thickness - I've seen variations of .040 -.050" from one end/corner to the other on a 4x8' sheet. Extruded sheet, however, is very consistent thickness due to being run thru rolled to size. Gluing plastic to aluminum or steel could be tricky. A cyanoacrylate glue (SuperGlue, CrazyGlue, etc) is probably best if you have a tight fit, but the joints may break if subjected to shock loads (sharp impact) or excessive heat. Note: "SuperGlue solvent" is just 50% mix of acetone & water - i.e. nail polish remover. (The acetone is what does the work.) Rich ------- Date: Thu, 15 Dec 2005 10:01:18 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Plastic recommendation Excellent material, Rich! I'm saving that post. As far as gluing plastics to metal, I wound up doing a fair number of test on this a while ago while trying to build an assembly jig for a fiber optic bundle. Specifically, I was looking for stuff that DOESN'T stick. Teflon was the clear winner in the "can't stick me down!" category, followed closely by Delrin. I managed to get everything else to stick. I tested two epoxies. One is Stycast, which I use at work for vacuum feedthroughs. The stuff is like tar, and needs to be heated to 60C in order to even mix in the catalyst, but it sets up hard, reproduces really fine detail, and sticks like crazy to just about anything that's had good surface prep (cleaning with alcohol worked well.) Another was Tra-Bond F113 Bipax. It's an optical epoxy, VERY runny. It comes in pre-measured packets, so to mix it you remove a clip and squish the stuff back and forth in the packet. It's got good capillary action, which is why I wound up selecting it for the fiber bundle. I did a test plate with a bunch of different materials stuck on it, including a chunk of aluminum that had a thin film of vacuum grease on it. Teflon didn't stick, Delrin kinda stuck, but nylon, PVC, aluminum, brass, and steel all permanently bonded to the test plate (which was aluminum). Even the greased aluminum stuck, which confused me greatly. As a result of all this I built the fixture out of Teflon and it worked like a charm. The epoxy bonded the fibers to their alignment fixtures, and the whole shebang popped out of the jig just fine. For plastic machining at home I like PVC because the stuff is so dirt cheap. Given the choice I'd use Delrin, but not if the parts need to be glued to other parts. After reading Rich's post here, I'm tempted to do more in acrylic. Tom ------- Date: Thu, 15 Dec 2005 19:03:29 -0600 From: Codesuidae Subject: Re: Plastic recommendation Alex Holden wrote: >How _do_ they get Teflon to stick to frying pans? Funny that you ask, my kid asked me that the other day, and I had to look up this link: http://www.discovery.com/area/skinnyon/skinnyon970606/skinny1.html Basicly they put on three coats, the first coat is a sticky version of the polymer, the second coat is the non-sticky version, but it still has a molecular affinity to the sticky version, then a third layer that is the non-sticky version with some bits of ceramic or other tough stuff to give the non-sticky some strength. More recently some clever guys have figured out how to bake a mixture of all the stuff so that it self- organizes and makes a better coating faster. :) Anyway, the info about the epoxies and whatnot was interesting and useful. I'm curious about the fixtures made out of teflon though, can you just buy chunks of it and machine it? Do you have to use a lube when you cut it? :D Dave K ------- Date: Thu, 15 Dec 2005 16:46:12 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Plastic recommendation NEAT! I'm sending that URL around here at work. I've had a slug of it sitting in my desk for ages. That's the one I used for the fixture (the biggest feature of which was 10mm long). But I checked in the shop, and we've got a fair amount of Teflon. I think it's the same as buying any other plastic. The stuff machines like a mix between nylon and Delrin. It's got a lot less tendency to make stringy hair than Teflon, but isn't nearly as dimensionally stable as Delrin. This was the first time I've really made parts with it. Neat stuff! Tom ------- Date: Thu, 15 Dec 2005 22:39:35 -0500 From: Rich Crook Subject: Re: Plastic recommendation >I'm curious about the fixtures made out of teflon though, can >you just buy chunks of it and machine it? Do you have to use >a lub when you cut it? :D I want to know how you hold on to it so it doesn't move! Kinda like grabbing a wet bar of soap... I knew a guy once who was flycutting a block of delrin - it slipped out of the vice jaws & the flycutter flipped it clear across the shop (a good 30-40')! Got *everybody's* attention right quick! Kind of in the same league as belt sander racing or chuck key tossing... (If you have to ask, don't! ) Rich ------- Date: Fri, 16 Dec 2005 09:41:28 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Plastic recommendation > I want to know how you hold on to it so it doesn't move! Kinda like > grabbing a wet bar of soap... It was. I took super light cuts and checked the setup over and over again. Even so, I did have some slippage and had to re-clamp and re-indicate a couple of the parts. But everything was done in a good ol' Anglock vise with parallels. Tom ------- Date: Fri, 16 Dec 2005 15:56:14 -0500 From: Stan Stocker Subject: Re: Plastic recommendation If you degrease the moving jaw of the vise you can stick 400 grit or so paper to it with double sided carpet tape. The fixed jaw can get the same treatment or be left as a reference surface as usual. Once done the jaw cleans up easily with a bit of solvent. In some other cases, two sheets of fairly fine abrasive glued together on the substrate side gives a slip resistance surface that isn't inclined to damage mill tables when used with a bit of discretion. This can be useful if you need to clamp a sheet down flat. Cheers, Stan ------- Date: Fri, 16 Dec 2005 21:58:29 -0000 From: "Lynn Livingston" Subject: Re: Plastic recommendation > (good luck trying to glue it!) Nah, it won't glue with anything permanently. But, welding it is easy and is permanent. Lynn ------- Date: Mon, 23 Jan 2006 15:09:45 -0800 From: Nicholas Carter and Felice Luftschein Subject: Re: Fly Cutter [taigtools] > I need to level the surface of an acrylic panel. > this part has to be flat accurate at a precision of 0.0004" > I want to program it to mill away all the material of the top. > Questions: > a. Can it be done with a regular cutter? (the panel is small) Yes, basically use a pocketing routine to mill across, step over, mill across, step over, etc. until done... > b. Or do I need a fly cutter to do it? is a fly cutter more accurate > then a regular cutter? Yes and no...with a small cutter you may get steps between passes. With a fly cutter you won't get as many steps, but the flycutter will magnify any misalignment of the x and y axis in respect to the spindle more than a small cutter would. A flycutter can use a roundnose tool and you can hone it to be razor sharp so that you will get a very smooth cut. Why not try both and see what happens? See our homepage at www.cartertools.com/nfhome.html ------- Date: Mon, 23 Jan 2006 23:11:46 -0000 From: "Lynn Livingston" Subject: Re: Fly Cutter Asi: What are you getting yourself into?????? ;-) I assume by prior posts that you are relatively new at machining? If so, then you are like a lot of us. I can't imagine getting myself into something that would require that kind of accuracy, and if I did, what tooling and setups it would take to do the job. How are you going to know if you have it machined to this spec? What kind of measuring device do you have that could measure and or compare a flat surface that would tell you for sure that it was within .0004 from one point to another across the whole surface? Are you grinding mirror mounts for NASA, or laser reflectors for IDOD?? ;-) Just curious... Lynn ------- Date: Mon, 23 Jan 2006 23:17:00 +0000 From: Tony Jeffree Subject: Re: Fly Cutter Machining anything flat to an accuracy of 4 tenths on a Taig mill is going to need very careful setting up - firstly to make sure that the column & spindle are accurately perpendicular to the plane of the table, secondly, to make sure that the plane of the table surface is accurately parallel to the plane of *movement* of the table (i.e., the plane described by the X and Y axes), and thirdly, that the material you are machining is clamped in such a way that the clamping action itself doesn't distort the material by an amount comparable to the accuracy you require. The latter in particular is going to be an interesting problem to solve with a material as flexible as acrylic. If you get the conditions described above right, the choice of cutter will be somewhat secondary in importance I believe. Regards, Tony ------- Date: Mon, 23 Jan 2006 15:36:17 -0800 From: Nicholas Carter and Felice Luftschein Subject: Re: Re: Fly Cutter leon_heller wrote: > A fly cutter doesn't produce a flat surface, it's very > slightly 'dished'. Leon Well a perfectly aligned machine would give a flat cut, but given that no machine is perfect, you will get a dish that corresponds to the amount of misalignment of the spindle to the table. And let me add to everyone else's comments, .0004" is getting into a situation where you would really use a surface grinder rather than a mill. Then again you could mill it then use a lapping plate to lap it flat. But then you need a lapping plate...and probably 3M lapping film, as compound would just get embedded into the acrylic. See our homepage at www.cartertools.com/nfhome.html ------- Date: Mon, 23 Jan 2006 16:01:08 -0800 (PST) From: juan gelt Subject: Re: Fly Cutter i suggest buying a 35 $ grade b granite slab certified to that and using it to both lap and support your sheet while cutting. if your eye sees cutter marks, you aren't there at 0.0004 yet. at that level of flat you should see a rainbow like on a cd. i'll bet a nickel you CAN NOT achieve that surface quality by any cutter on a taig. it's a beautiful little beast, but everything has a limit. cheap precision reference stuff, including the amazing 300$ 3 FOOT by 4 FOOT 4 inch thick granite slabs...i can't believe the prices... shipping prices are sort of...angioparalytic [usual disclaimer- no financial interest, opinions my own, etc.] ------- Date: Tue, 24 Jan 2006 14:01:06 -0000 From: "combelis" Subject: Re: Fly Cutter To all of you interested in what I want to do, here goes: I need to make panels from clear acrylic 0.23" thick. After I cut the panel for holes, shape etc', I need to engrave. How is the engraving being done? First, I apply 3 layers of white paint on the clear acrylic. Then I apply 2 layers of black paint. Now comes the tricky part :) I need to engrave only the black, so the final result will be a black panel with white letters. This panel will be backlit from behind. Problem is that sometimes the cutter "eats" the white too, leaving a clear letter, which is a bad result for me. The 3 or 4 layers of white give about 0.002" thickness. (I don't want to use "whole white acrylic", simply because the white text doesn't look as good as paint). I assumed that the acrylic panel was very accurate and flat, and the paint is causing the diference in the surface level. But my indicator showed that the clear acrylic has height differences along the surface at about 0.0015". How do I know that? I checked the panel at 8-10 different points. If I can make the basic clear acrylic accurate and flat, the painting will not harm the accuracy level of the surface. Then I'm ready to go. I want to say that I already succeded doing my first panel :) How? Well, it took me a while, but it's my hobby so I enjoy spending the time. I mapped the g-code, in such way that I know the g-code block for each letter. Then I find the highest point of the panel using the indicator. (Simply move it to 8-9 deferent points). I bring the cutter to the highest point, finds the surface level and start engraving at 0.001". After it finishes, I check which letter is O.K and which one need to go deeper. The ones that are o.K, are removed from the g-code. Then I go deeper more at 0.0003" etc. Until all the letters are engraved properly. I know this method takes time, and this kind of job isn't built for this mill,but if there is one major thing I learned from this group is: "if it works, it works :) " I believe that if I can level the clear acrylic, it will save me the time of the process I described above. Asi ------- Date: Tue, 24 Jan 2006 14:10:40 +0000 From: Tony Jeffree Subject: Re: Re: Fly Cutter Sounds to me that you are introducing a further problem here - that of ensuring that the layers of white paint are of a consistent thickness (not a trivial thing to do IMHO). The more conventional approach to this kind of job would be to screen print rather than machine away the top layer - have you thought about that as an alternative? Regards, Tony ------- Date: Wed, 25 Jan 2006 19:11:26 +0000 From: Tony Jeffree Subject: Re: Re: Fly Cutter 25/01/2006, you wrote: > I thought these were to be backlighted. I don't think silkscreened > characters would work... Neil Savage You don't silkscreen the *characters*, you silkscreen the background colour *around* them (in this case, black I assume). So if the material you are screening onto is translucent & you use an opaque ink, the characters can indeed be backlit. Regards, Tony ------- Date: Wed, 25 Jan 2006 10:50:41 -0000 From: "infidel21st" Subject: Re: Fly Cutter Asi: Have you checked the forums over at Viperpit.org? There is a lot of experience over there making cockpit panels using the CNC taig. I believe the material of choice is delrin. I haven't seen anything to date indicating there was this kind of issue. Chris Crowley ------- Date: Wed, 25 Jan 2006 13:24:42 -0000 From: "combelis" Subject: Re: Fly Cutter Chris: How did you know I'm doing those kind of panels? :) For those who are interested, I'm a simulator fan and I'm building a replica of an F-16 Cockpit. I already spoke with Mike from ViperPit. He is using "white" Acrylic so he doesn't have the problem like me. The thing is, IMHO, that using "white" acrylic doesn't give the same results. The text comes out a little dim. Asi ------- Date: Wed, 25 Jan 2006 11:29:41 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Re: Fly Cutter >> first, I apply 3 layers of white paint on the clear acrylic. then I >> apply 2 layers of black paint. Now comes the tricky part :) >> I need to engrave only the black, so the final result will be a black >> panel with white letters. this panel will be backlight from behind. >> problem is that sometimes the cutter "eats" the white too , leaving a >> clear letter , which is a bad result for me. The 3 or 4 layers of >> white give about 0.002" thickness. >> (I don't want to use "whole white acrylic", simply because the white >> text doesn't look good as paint). On Wed, 25 Jan 2006, Lam wrote: > Hi Asi this might be considered cheating but i would just mask up the > black near the clear letters and airbrush in the white for a final > touch up : ) Following up on what Lam said, take a look at this: http://www.cuttingedgecnc.com/vinyl.htm In this, the author details all of their attempts at making a rotary knife holder for a CNC Sherline for cutting vinyl. They go through five iterations on the blade holder, and pay attention to enough details that the thing will cut the vinyl but not the backing. As far as doing multiple parts that need to be in registration to each other, the author has info on doing that as well. If you could CNC your masks, apply them to your panel, airbrush around them, and then peel the mask off, you may be in good shape. Plus, you'd have a CNC vinyl cutter in your shop to boot. Can't beat doing a project and getting a tool out of it. Tom ------- Date: Tue, 04 Apr 2006 06:15:01 -0000 From: "Chuck Fellows" Subject: UHMW Bearings [LittleEngines] Anybody ever tried making crankshaft bearings for a small steam or compressed air engine out of UHMW? Chuck ------- Date: Tue, 4 Apr 2006 09:07:30 -0700 From: "corey renner" Subject: Re: UHMW Bearings I've used UHMW to make bearings before (also used it to make a replacement rib for a convertible top on a '66 beetle) it worked well. I've never used it in an engine, but I would imagine that it would work well for that too. cheers, c ------- Date: Tue, 4 Apr 2006 10:26:41 -0700 From: "rwremington" Subject: RE: UHMW Bearings Materials such as Delrin and glass reinforced Teflon (Rulon) are usually considered better bearing materials than UHMW polyethylene. There are some graphite/molydbenum disulfide filled plastics that would work as well. Dick R. ------- Date: Tue, 4 Apr 2006 13:43:30 -0700 From: "corey renner" Subject: Re: UHMW Bearings On 4/4/06, James E. Andreasen wrote: > I know I'm dumb, but what is UHMW? James Not dumb at all. It stands for Ultra-High Molecular-Weight Polyethylene. Pronounced as "Ump-ee" on the shop floor. It is a food-grade self- lubricating plastic. It looks similar to white Nylon, but is dimensionally stable and doesn't absorb water (hence food-grade). I used to design food- grade conveyors and we used the stuff a lot. I used to take a lot of cut-offs home for my shop. cheers, c ------- Date: Tue, 04 Apr 2006 20:54:11 -0000 From: "Chuck Fellows" Subject: Re: UHMW Bearings I have a fair amount of the stuff that I picked up on eBay. I know it's a little tricky to machine, since it's kind of springy and tough. But it seems like it would have enough flexibility to compensate for bearings that weren't in perfec alignment (not that anyone in this group would ever make an engine with bearings slightly misaligned :)) Chuck ------- Date: Tue, 4 Apr 2006 14:02:43 -0700 From: "corey renner" Subject: Re: Re: UHMW Bearings The key to machining it is very sharp tooling. It cuts well, but if the cutter rubs it just makes a mess. c ------- From: "benedict-listx~xxhawaii.rr.com" benedict-listx~xxhawaii.rr.com Date: Wed May 10, 2006 1:34pm(PDT) Subject: Re: How to lathe plastic? [taigtools] On 10 May 2006, phoneteamd wrote: > I am a complete newbie. I am trying to round a set of pinewood derby > wheels on the lathe. How do a cut the plastic? What RPM? My first > attempt has caused bumps like waves on the top of the wheel tread. > How do I make it cut smooth? Here's how I'd do it: Make sure the wheel is mounted super super solidly. What you're describing sounds like chatter. Since you're making an interrupted cut (each gap in the tread will let the tool stop cutting and start again on the next tread), rigidity is going to play a big role in this. Make sure your tools are hair-splitting sharp. This isn't a cure-all for the kind of chatter you describe, but it helps a ton. After grinding I dress my tools with a little diamond hone I picked up from the hardware store. Nothing special here, and any hone would work. At home I use a Norton stone for this step. You should be able to shave your fingernail with the tool by the time you're done. Also make sure there's a SMALL radius at the tool tip. I don't do this on the grinder since it's hard for me to control. After dressing the tool I pass the hone around the tip of the tool a couple of times. Depending on the radius I want I use more or fewer strokes with the stone. Three strokes is enough for me to see the difference between it and a razor- point tool with no radius. The radiused tool will cut silky smooth while the razor-point tool will cut grooves. Use a slow feed across the wheel. Going fast will make grooves rather than a smooth surface. Ideally your tool advance per revolution on a finish pass should be on the order of the radius on the nose of your tool or smaller. Listen to the cut. If it's squealing, something's up. Take a heavier cut (probably not possible if you're truing wheels), slow down the spindle, or feed faster. If the combination you need means you're cutting grooves instead of a smooth surface, then try adding more of a tool tip radius and try again. Something to consider is using some sort of lube or coolant. Plastic tends to do ok cut dry, but it can do weird things if it heats up enough to flow. Try dribbling a little water during the cut, just to see what it does. One lube trick I picked up here on this list was to use cetal alcohol. I started using this as a tapping fluid, and it works GREAT. I can't remember who wrote this particular tip, but Chapstick is primarily cetal alcohol. I keep a stick in my toolbox at work now. I haven't tried it on plastic, but it's worth trying if it stands a chance of giving you a better cut. All machining considerations aside, have you checked the rules and regs where you'll be competing? A while back when I was looking at cutting a pinewood derby body on the CNC mill (I know... I know... I'm SICK) I saw a lot of competition rules expressly forbid the use of machine tools on the wheels of the car. The ones that did allow it tended to limit it to things like you're doing, namely truing up the wheels but not modifying them in any other way. Some excluded even that (which makes no sense to me, since the alternative they suggested was to chuck the wheel up in a drill and basically do the same operation.) Just be sure of the rules before you compete. Hate to get a DQ over a technicality like this. Tom ------- From: "benedict-listx~xxhawaii.rr.com" benedict-listx~xxhawaii.rr.com Date: Wed May 10, 2006 6:22pm(PDT) Subject: Re: How to lathe plastic? On 10 May 2006, phoneteamd wrote: > Wow! This is a big help. I have a bunch of old wheels to experiement > with. You have given me a lot of ideas to get me started. > One thing I don't understand is what tool to use to cut with? When I > purchased my lathe it came with a six piece set of cutting tools. The > are "left,right,45 degree,round nose,boring bar, and cut off" Which of > these should I try? lso any ideas on angle to hit the wheels with? Typically turning cuts on a lathe start at the tailstock end and move toward the headstock. For what you're doing this is the way I'd do it. The tool you'd want for this kind of cut should look like this (pardon my ASCII art): |\ | \ | \ | \ | | | | | | |XXXXXXX| |XXXXXXX| Ok, ok, so that's not the best rendition of a lathe tool I've seen, but it's a try. I know the angle at the tip isn't that steep, but you get the idea. I'd hit the wheel with the tool just about in that orientation. The idea of the angles at the tip are to provide clearance so the tool doesn't rub. So long as only the tip of the tool is touching the wheel, you should be in good shape. Of course, as you might've guessed, theres more to it than that. The tools that come with the Taig lathe are a pretty good generic set of tools, but the angles really aren't ideal for any one material. They're a good compromise for several. In the long run it helps to grind your own. The best bet for grinding tools is to get some tool blanks, a grinder, and some seat time. Sherline's got a really nice guide for grinding lathe tools: http://www.sherline.com/grinding.htm The one difference between what's said there and what I do at home is I don't break the tip on the grinder. I do it by hand with a stone. My fine motor skill is so-so, and I tend to put huge chamfers on my tools if I do them on the grinder. I also notice the recommendation that tools not be dressed with an oil stone after grinding. I can't say I share the same opinion, but that's all it is: an opinion. If the idea of grinding your own tools makes your stomach sink, don't sweat it too much. I've wasted plenty tool blanks trying to get a particular shape on a tool. It's a matter of doing it until your hands know what to do. And lathe tool blanks are cheap, all things considered. I do curse under my breath when I screw up a lathe tool. But I curse out loud when I screw up an end mill, especially if it hasn't seen more than a few minutes of service. > Thanks so much for the help. You betcha. Best of luck with those wheels. Tom ------- Carbon fibre [taigtools] Posted by: "Chris Ghent" cghentx~xxtpg.com.au Date: Tue Jul 4, 2006 12:10 pm (PDT) Anyone know if it is possible to machine carbon fibre, and if so what is the nearest equivalent to the way it behaves? Plastic? Wood? What sort of cutters would you use? Apologies for lack of direct Taig relevance, but this is the only machining group I belong to. best wishes Chris ------- Re: Carbon fibre Posted by: "Jeffrey Wittman" eyecreatex~xxhotmail.com Date: Tue Jul 4, 2006 12:35 pm (PDT) As of late, I have been doing a fair amount of carbon machining, and the feeds and speeds are similar to plastics. The only difference being the cutter. You need to have a diamond coated cutter, and they are a little pricey (40-50 bucks for a 1/8th inch 4 flute), but they really are the only bits that you will have any life with (believe me I have tried many others). They are usually refered to as an "amorphous diamond coating", but there are several different types. Check out Niagara Cutter online, as they will give a good idea of what you are looking for. (They make cutters specifically for carbon:) BTW, I dont know if it is relevant to your application, but if you need to do any machining of fiberglass, they also require the same kind of bits as they are more abrasive then carbon composites are. Jeff ------- Re: Carbon fibre Posted by: "Doug Stout" kingshouse41225x~xxgmail.com Date: Tue Jul 4, 2006 9:16 pm (PDT) I have machined both carbon fiber and fiberglass, and with the proper endmill they do machine quite nicely. Aside from the diamond coated EM, I will add that flood coolant helps dramatically, and is simple to set up, even on the taig. Fabricate, or have fabricated a pan which fits on the table. Run a drain from the back side of each end down into a bucket on the floor. A submersible pump, run to some flex hose and a nozzle mounted on the mill and you are in business. The coolant not only helps extend the life of the tool, it eliminates the dust. ------- Re: Plastic types and suppliers? -- [taigtools] Posted by: "Richard" phrhx~xxworldnet.att.net Date: Thu Jul 6, 2006 3:40 pm (PDT) A nice to machine material is PVC such as schedule 40 pipe. I cut pieces fom 6" diameter pipeand heat it in a scrapped electric grill and it becomes flat and can be made really flat when a cement block is used to cool it on a concrete floor. An example of what can be done with it is shown in the links section in this group under Richard's shop. Look at the cheap dividing head. It glues up very nicely with PVC glue. Smaller diameter schedule 40 PVC is a great cheap material for lathe practice for threading practice if you are so equipped. Richard ------- Re: Plastic types and suppliers? -- Posted by: "Richard" phrhx~xxworldnet.att.net Date: Fri Jul 7, 2006 5:11 am (PDT) > Do you have any problems with outgassing of the pvc when you flatten > it? What temperature do you set your electric grill to when you do > this? I like the idea. I will have to give it a try. I have never measured the grill temp but set the dial (Sunbeam grill from walmart) between low and medium, Not very hot. The PVC pipe section unrolls when it gets warm enough and can be sandwiched between concrete blocks or anything flat and heavy to cool and it will stay flat. I have not noticed any gassing or nasty odors! ------- Re: 4 Flute vs 2 Flute in plastic [taigtools] Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Wed Oct 18, 2006 9:55 am (PDT) Ackley, Ray (R.J.) wrote: > Hi all, > I'm a bit of a machining beginner here and I found some peculiar > behavior with a 4 flute bit I picked up. > When I run the 2 flute bit I got through Nick/Taig though the plastic > I'm cutting it cuts perfectly clean and quietly at any spindle speed. > But the bit isn't deep enough for my needs, so I picked up a 4 flute > thinking "Hey, if 2 flutes are good, 4 must be better, right?". Wrong. > The 4 flute makes a terribly loud sound when cutting and also wind up > "flaying" the plastic in such a manner as it creates extremely fine > strands that somehow melt it back into place? The end result is a "cut" > plastic edge (by the sides of the bit) that has some kind of a weird > plastic fuzzy "hair" on it. It's very odd. > My google searches on 2 and 4 flute differences have yielded NOTHING > that could possibly explain this. Any ideas? > Thanks, Ray Ackley I'm going through some plastic machining hell myself. You want less flutes rather than more, and you want a slow spindle speed. The key is to not melt the plastic, or even soften it by overheating. You want to make the biggest chips possible. You can take a endmill and relieve the shank above the flutes a bit on the bench grinder (or surface grinder for a better grind) so you can use a short flute on a deep part. I was talking to Forrest at Taig and he said they used to put a stream of CO2 (or a Vortex type cold gun) on the part to keep it cold while cutting, I just bought a 1 flute plastic routing bit (specially made for soft plastic, by Onsrud) because I need to mill some UHMW and even a 2 flute endmill was melting the part a bit...$20 or so and carbide so I assume I'll destroy it accidentally... See our homepage at www.cartertools.com/nfhome.html ------- Re: 4 Flute vs 2 Flute in plastic Posted by: "Ackley, Ray (R.J.)" rackleyx~xxford.com Date: Fri Oct 20, 2006 8:16 am (PDT) Well I put in the new 2-flute and it works great... simple as that! ------- Machining Delrin [taigtools] Posted by: "davidjaypark" davidj93x~xxhotmail.com Date: Wed Feb 21, 2007 5:45 pm ((PST)) Hi all: Just curious to note if any of you have experience machining black delrin plastic? If so was interested in getting your thoughts in respect to speeds and feeds. Will be using a 1/4 flat end mill all the way down to a 1/32 ball nose end mill. Use a Mfg. calculator but the largest material multiplier is 2 for aluminum. It doesn't have any numbers for plastic, so I thought I would ask you guys. IF you could let me know your experiences with milling Delrin using the Taig and what your feeds & rpms were it would be great! Thanks so much for the help and will talk to you soon! Parkman ------- Re: Machining Delrin Posted by: "Roy" rx~xxshred2.net Date: Wed Feb 21, 2007 6:33 pm ((PST)) You can pretty much rapid through black Delrin in my experience. You'll want to go fairly fast to avoid melting it. I don't have a speed/feed off the top of my head, but some places suggest 400 sfm for HSS. Here's a link: http://www.cncplastics.com/PDFs/Machining%20Acetal%20Delrin.pdf ------- Re: Machining Delrin Posted by: "Landrum Haddix" lhaddixx~xxiglou.com Date: Wed Feb 21, 2007 6:55 pm ((PST)) Parkman, I used something like 10K rpm and 5ipm with a 1/8" cutter and .060 doc. It's made to be machined, it doesn't seem to care. It didn't try to melt even at that high of an rpm and low feed. Acrylic is totally different, but Delrin is ideal for cutting. A 1/32 ball end mill is going to break if you feed very fast and it's so small you can't go too high on RPM so it's a matter of what feed it will tolerate. If you are going to play with feeds on that be sure you have two or more mills on hand. I found a 1/16 end mill snaps somewhere between 10-15 ipm on acrylic. (I had to go for 15 and was sorry.) BTW if you ever need to cut something that melts easily like Acrylic, Harvey tool http://www.harveytool.com/ makes funky single flute cutters for plastic, but you don't need these for Delrin. It's fun and makes my enclosure look like one of those paperwieght snow scenes. Just for giggles here is a pocket in Delrin: http://lhaddix.net/machine/dustcover.html Oh, yeah you can use double-sided tape for fixturing as well. Landrum Haddix http://web.qx.net/lhaddix ------- Re: Machining Delrin Posted by: "Jeffrey Wittman" eyecreatex~xxhotmail.com Date: Thu Feb 22, 2007 6:01 pm ((PST)) At some point you may run across some reinforced acetal (Delrin is a trade name btw). Typically it comes with a glass reinforcement (fiber, powder, of micro spheres), and will quickly dull your bits. I have run into this because I often buy surplus (usually unlabelled). In this case try a diamond coated bit, which I have used on fiberglass, and carbon composite sheet with great success. Jeff ------- Machining UHMW on a shaper? [Metal_Shapers] Posted by: "Bill" manincocamox~xxyahoo.com Date: Sat Mar 17, 2007 12:09 pm ((PDT)) Hi All: Has anyone tried cutting UHMW on a shaper? [Ultra High Molecular Weight Polyethylene] Any tips or ideas on cutter angle grinding? Thanks Bill ------- Re: Machining UHMW on a shaper? Posted by: "Geoff Kingma" gkingmax~xxinterlog.com Date: Sat Mar 17, 2007 4:32 pm ((PDT)) I have used it on the shaper many times and it cuts very well. On the trailing edge though, the cut piece will still adheres so it looks terrible. A quick shave using a sharp knife cleans it up. I would say that the finish rivals that of aluminum. Geoff ------- Re: Machining UHMW on a shaper? Posted by: "Bill Williams" BWMSBLDRx~xxPeoplePC.com Date: Sat Mar 17, 2007 6:17 pm ((PDT)) > For those who aren't familiar with UHMW, my observations: it's a great bearing, hammer or slide material. Almost like a resiliant form of bearing bronze or aluminum in use. Very slippery material. I use it to shape sheet metal parts. Bill < You have had the experience that I have had; UHMW bumping hammers are a great starting point for forming aluminum and it turns nicely. Unlike nylon that tends to roll the chip over the tool tip and wind itself onto the cut surface, welding itself back on! Bill in Boulder "Engineering as an Art Form!" ------- Re: Machining UHMW on a shaper? Posted by: "Ed Godwin" eng4turnsx~xxyahoo.com Date: Mon Mar 19, 2007 10:25 am ((PDT)) Ultra High Molecular Weight Polyethylene. High Density Polyethylene (HDPE) is used for water and natural gas piping systems. Good stuff in many ways but it's worth a little study of its mechanical properties if you're going to machine it and use it for something of a precision or load-bearing nature. First of all, it tends to "give" when cutting so that if you think you've shaved off 0.050", you've actually taken off less than that. Also, if you're going to stress it in use, it has both a short and a long-term strength. You must use the lower long-term strength for any stressed part. Also, like Teflon, it will tend to flow with time. I've cut it successfully on the mill and the lathe with standard HSS grinds for steel but I'm sure you could do better with a little experimentation. Steeper rakes and less edge support would work well with this material since it has little resistance. A razor edge should be beneficial so it will shear instead of tear. HDPE in the color black is somewhat abrasive to the cutting edge due to the carbon black used to color it, so keeping the tool sharp is an issue if you're cutting a lot in the sense of production quantities. Overheating is an issue so don't overspeed. And the trailing edge of the cut will benefit from a sharper tool bit. If you use a sacrificial piece on the trailing edge of the workpiece, you will get a nice sharp edge. Since it cuts so easily, you will be tempted to take huge gobs of it off with each stroke. Resist this temptation and you'll get a better quality. Also, since it's relatively soft, simply clamping it in the vise will distort it, again calling for lower cutting forces than you might be tempted to apply. As with all things soft, a gentle touch works best. Ed ------- Re: Help needed [atlas_craftsman] Posted by: "uhmgawa" uhmgawax~xxthird-harmonic.com Date: Thu Sep 13, 2007 6:32 pm ((PDT)) artrich999x~xxaol.com wrote: > Is there some company or someone that can supply small, hobbyist-sized quantities (and prices) of acrylic plastics, or other machinable plastic? Needed is clear acrylic rods in 1/2" dia. up to about 1" dia. in pieces 3" to 6" long. Cutoffs, or slightly damaged pieces will do fine. < I don't know where you might find the red lens material but you might want to have a look at www.usplastic.com. Their minimum quantity purchase is fairly low as I recall. You might also check out www.use-enco.com as they carry plastic raw stock in various shapes. uhmgawa ------- Re: Help needed Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Thu Sep 13, 2007 8:07 pm ((PDT)) One great place is US Plastics. You won't get cutoffs, but they have nearly any sort of plastic material in many shapes and sizes. I mostly buy Teflon stock from them, but they have a TON of stuff in their catalog. I know their price on Teflon beats any other source. I think their minimum order is pretty reasonable, but then Teflon is pretty expensive stuff in general. Jon ------- Re: Help needed (Plastics source) Posted by: "azbruno" azbrunox~xxyahoo.com Date: Thu Sep 13, 2007 10:42 pm ((PDT)) First, nobody's mentioned yet the difference between cast acrylic and extruded acrylic. You want cast acrylic for machining. Extruded does not machine well at all. TAP has lots of extruded. I think you can get cast in clear, but not colored. My source is Delvies (http://www.delviesplastics.com/). The cast acrylic rod is sold in 4' pieces and the minimum is only $35. I've done a lot of searching and their prices are about the best I've found. You night be able to get all you need for the minimum. If you find short scraps, make sure you know what it is. I once ordered some rods of cast acrylic and was mistakenly shipped extruded (not Delvies). I could tell by the way is reacted when I used a small saw to cut off a piece... far more brittle. Bruno ------- Re: Help needed ... small lot acrylics [sherline group -- same question] Posted by: "jthandbook" jthandbookx~xxverizon.netp Date: Thu Sep 13, 2007 3:23 pm ((PDT)) Hi Art... You might consider Small Parts, www.smallparts.com. Their online catalog is incomplete but email inquiries get a fast response, service is as good as it gets. And they sell down to 3 inch lengths in cast acrylic round. Best, James ------- Turning Acrylic [sherline] Posted by: "steve" steve12345x~xxtalk21.com Date: Tue Oct 16, 2007 8:38 am ((PDT)) Hi, has anyone machined 'Acrylic' on his lathe and is able to give me advice on what speeds/feeds to use and what shape the cutting tip should be. The plan also calls for cutting a thread in the acylic for attaching the lid. After machining is there any advice on polishing? I'm making a small fuel tank for a model aircraft engine and I'd like to make it to drawing if at all possible. Thanks in advance. Steve ------- Re: Turning Acrylic Posted by: "Tony Horstman" tonyx~xxoryx.net.au Date: Tue Oct 16, 2007 4:06 pm ((PDT)) Steve: Acrylic is fun to turn. Speed should be slow to medium, because the material will melt quite easily. Keep the workpiece wet - I use plain water with a drop of dishwashing detergent for acrylic - you will quickly get a feel for speed and depth of cut versus surface finish. Tools should have rounded nose (for finish), but with a sharp upper cutting edge. Acrylic takes threads beautifully, as long as you observe that sharp peaks will be inherently very weak and prone to chipping. Acrylic, however, for all it's good turning and fantastic finish, is prone to stress cracking brought on by exposure to solvents, alcohol and hydrocarbons. Damage may not immediately be apparent, but a day later you may find you wonderful part neatly shattered. I googled this page, which is useful: http://microadvances.com/chemicals1.htm For a fuel tank, why not try polyethylene, delrin or similar - even easier to turn. Tony H ------- Re: Turning Acrylic Posted by: "Tony Horstman" tonyx~xxoryx.net.au Date: Wed Oct 17, 2007 6:32 pm ((PDT)) Steve: You're going to be disappointed with acrylic in contact with this mixture. It will most certainly disintegrate after a short period (often overnight, which makes taking a second look at your newly machine masterpiece really sad). Tools must be sharp for plastics, otherwise the tool rubs too much and melts a blob rather than peeling off a nice string. I use acrylic to machine small molds for vacuum casting (good to see what's going on inside, and easy to get a mirror polish). I recently got most of the way through a fairly complex core and cavity and picked up a nearby marker pen to mark a face that needed some extra work the next day. Put the core and cavity together, went home satisfied with progress. Next day saw the core neatly cleaved into 3 pieces on the bench. The solvent in the ink had evaporated in the closed cavity and cracked the part. Leaving the cavity open would've saved it. Live and learn. Tony Horstman ------- The use of plastic as a gib [atlas_craftsman] Posted by: "Bobby May" widgitsx~xxsbcglobal.net Date: Thu Jan 17, 2008 4:22 pm ((PST)) DennisF MacIntyre wrote: > I read a post a year or two ago where someone said what type of plastic > it was and why it is better (longer wearing)than the original equipment. Although many types of plastic could be used for this purpose we have to ask ourselves who knows more about these machines. The Engineers and machinists who designed and built them or the guy's who use them everyday. Several machine manufacturers have used plastics as a liner wear surface for gibs. One that I can think of from the top of my head is Fadal. They used to make the gibs for the box ways on their CNC vertical mills out of aluminum and line the wear surface with Turcite. The aluminum worked well to support the weight and the thin plastic Turcite shim gave it a smooth surface to slide against the box ways making the ways actually last longer. Fadal recommends also the use of Vactra #2 waylube for their machines But several things were considered before doing this such as the weights and forces applied to the parts in question vs the yield stregnth vs the drag (Cv) and stiction (static friction). The plastic also acts as a sacrificial media in case chips (swarf) get between these 2 surfaces. It actually allows the chip to get imbedded into the plastic and this reduces the scraping effect by reduction of weight and surface area above the chips. Better way of putting it would be that the chips don't get smashed into the ways Turcite works very well for this type of application. Pretty blue color. Rulon would be a good choice for bushings for shaft applications as long as the speeds and loads arent too high as it is much softer than Turcite. Deep red color. Torlon makes nice bushings and wear surfaces also, a bit pricey. Gold in color. Teflon (PTFE) is too soft and it changes size with just a few degrees of temperature change. White in color. Nylon would work but it wasn't compounded for this application and it's a bit softer than the others as such would wear much quicker. White to Cream yellow color. Polyethylene and polypropylene are also way too soft, even the UHMW (Ultra High Molecular Weight). White to clear white color. Vespel would be an optimum choice to make a gib out of as it is quite stiff and offers the lowest drag coefficient (Cv) out of them all, but the formula for making it and the patent rights have not yet run out to other manufacturers. Dupont owns it, Damn if it's not expensive !!! I was buying a billet of Vespel every couple of months for making some real expensive parts. A 10" x 10" x 2" thick blank costs just over $9000. Yes, thats $9000 US dollars for 200 cu. in. of plastic. I call it a bit expensive, but it's good stuff. Too expensive for making gibs out of. Deep Brown in color. Hope this helps By the way, I uploaded a cool PDF file (Fasteners_Handout.pdf) in the atlas_craftsman files section on fasteners and threads, It has some very good info if you like designing new stuff to build on your machines. Later Bobby May ------- Re: The use of plastic as a gib Posted by: "Bobby May" widgitsx~xxsbcglobal.net Date: Fri Jan 18, 2008 4:33 am ((PST)) Bill brought up the idea of using Delrin. This would be a good cheap plastic for making a gib out of. But I would anneal this before fabrication. I know, how can you anneal plastic? For delrin pop it in momma's oven at 200 deg F for about 4 hours for a little piece- 6 hrs if it's larger. This drives the moisture from the plastic making it stiffer and more stable for holding physical sizes. Plastics have many names for the same product. Delrin is DuPonts name for Acetal. But it's also known as Polyacetal, acetal resin, polyformaldehyde. And other manufacturers call it Celcon and Kepital. But it's made with formaldehyde. This is the smell you get when cutting it quickly; small quantities from smelling this stuff won't hurt you too bad. Something interesting about plastic names. Lexan belongs to GE (General Electric Plastics division). Everyone else has to call it Polycarbonate. Lexan outgases whats called Bisphenol-A, bad stuff as it is known to cause cancer and birth defects. Good tough stuff in the thicker sizes especially if you want to stop bullets. Teflon belongs to Dupont. Everyone else calls it PTFE (Poly Tetra Flouro Ethylene). Note the first and last word in PTFE -- Poly and Ethylene. Yes, this is the stuff they make TupperWare bowls and Cool Whip lids out of. It is also the base compounds for making Teflon. The stuff in the bottom of momma's fry pan is actually a form of thermoset teflon that is sprayed on like powder coating and then baked. Acrylic (PMMA) belongs to Rohm and Haas. Its real name is Polymethyl Methacrylate, that's a mouthful. Others call it Plexiglass and Lucite, but there's tons of other names for it also. Something cool is the use of some compounds for other things like cyanoacrylate (Crazy Glue). I would say that my biggest point here is to choose your plastic materials wisely. And be careful cutting some raw materials you might get for nothing as scrap rems as it might be very bad for your health. "No Way Bobby, that's not bad stuff." I have heard this many times before. Take a few minutes and look up "Aluminum Poisoning" on the Internet. You will be VERY surprised at what you learn. Here's one: http://www.squidoo.com/aluminumpoisoning Later Bobby May ------- Re: The use of plastic as a gib Posted by: "Michael Fagan" woodworker88x~xxgmail.com Date: Fri Jan 18, 2008 7:24 am ((PST)) Delrin is one of the best, IMO. Hard enough to machine with good dimensional precision, soft enough to be easy to machine and act as a bearing. It also comes in several (expensive!) variants for different applications. Two of my favorites are glass-filled Delrin, used for making abrasion-resistant components like chain guides, and Delrin AF, a teflon- filled delrin that is basically self-lubricating. I use it for glides, sliders, and wheels. Neither is cheap, but most applications don't need much. I buy them through McMaster-Carr. Keep the Delrin AF cool while machining, since hot Teflon is a big problem (health hazard). For the glass filled material, take the same respiratory and machine precautions as if you were machining fiberglass, although it's much better in terms of machinability and surface finish. Michael -------