Post by thread:[OT]: Cutting acrylic/lexan/plexiglass

Looking for suggestions on making smoother curved cuts in 1/8" and 1/4" acrylic. urrently I use a Dremel rotary tool with a Roto-zip type cutting bit (rotary/spiral saw bit) but get very jagged edges. Anyone know if there a better bit I could use for this? Perhaps a Dremel 194 high-speed cutting bit would work better? Or is there another process I could use for this? Scoring/snapping and circular saw with carbide-tipped bit are the only other processes I know for this, but they are just for straight cuts. Cheers, -Neil. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I've cut lexan and PVC sheet using a Jig Saw with a special plastics blade. The blade has teeth on both leading and trailing edges so that the trailing edge teeth clear the cut. Using normal blades you often end up just melting the stuff and getting the blade jammed in the plastic. 1/8" might be a bit thin for this type of saw though. Perhaps a smaller hobbiest version could be used? Not sure if the blades are available for those though. Andy -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Looking for suggestions on making smoother curved cuts in > 1/8" and 1/4" acrylic. urrently I use a Dremel rotary tool with > a Roto-zip type cutting bit (rotary/spiral saw bit) but get very > jagged edges. I use a Dremel jigsaw with a fine mini-hacksaw blade that has around 20 tpi (teeth per inch) ground down, er, with a grinder, to about 2mm width (from the original 5mm).Also, it is important to (a) support the underside of the cut with a piece of scrap board (b) not cut an exposed acrylic surface.This depends on which way you have the blade - electric drill type jigsaws (and circular saws) cut on the up stroke, the Dremel can cut on the down stroke, if that's the way you put the blade in. I use paper-like packaging tape (if the original protective paper is gone), particularly on the surface that the blade is cutting towards (c) use a sharp blade that has a reasonable offset to remove waste. If you don't you'll just end up melting your way through and the cut closes up behind the blade. Triangular teeth are not as good as shark-fin teeth as they don't remove waste so readily and the plastic tends to clog the blade (d) don't cut at a speed that causes the plastic to melt (e) if possible, pre-score the cutting line with a scalpel or modelling knife. This stops any chipping into the required finished area, just as you would do so if chiselling wood. You can leave 0.5mm or so excess outside the line for sanding or filing Taking these precautions I can satisfactorily cut acrylic even on the bandsaw, which has a nasty 6 tpi wood blade, although for finer work I prefer the Dremel -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> curved cuts they use a router, though they couldn't > find out what bit they use. A router does work, but you have to be very confident with your tools and jig. Acrylic will shatter all over the place. I've used a 6mm carbide flute a couple of times making cut-outs for LCDs but didn't feel terribly comfortable doing it. You can get 3mm flutes, although that probably wouldn't make a lot of difference generally unless you're interested in the internal radius of corners (that you could finish off with a square or rat-tail file anyway) -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 11:49 AM 5/15/02 +1200, you wrote: > > curved cuts they use a router, though they couldn't > > find out what bit they use. > >A router does work, but you have to be very confident with >your tools and jig. Acrylic will shatter all over the place. I've >used a 6mm carbide flute a couple of times making cut-outs >for LCDs but didn't feel terribly comfortable doing it. You >can get 3mm flutes, although that probably wouldn't make >a lot of difference generally unless you're interested in the >internal radius of corners (that you could finish off with a >square or rat-tail file anyway) One really nice way is with a table saw. Micromark in FL (USA) has a little table saw or you can use a full-size one with the proper blade. I think it should be carbide, but check. And be particularly careful that you don't lose any fingers. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Machine cutting of plastic is not much different than cutting metals. The cutting tool applies pressure which increases the temperature of the material just ahead of the cutter. The sharp edge then peels away the heated region. Since acrylic materials don't conduct heat well, the region just in front of the cutter will heat very quickly, and will stay hot longer than say, aluminum or steel. The two things to master in cutting plastics is to make sure the cutter doesn't stay in one place too long - meaning that the feed rate has to be pretty high, or else it will make an ever-increasing pool of molten plastic from which chips can't escape; and that the feed isn't too fast, or a tooth will try to peel off material that is still too cold and hence hard, causing a fracture. The same is true with rotating cutters and reciprocating or band saws. I second the comments about work holding. Good clamping will prevent fractures from the occasional blade hang-ups that can occur. I routinely cut acrylic sheet with end mills, band saw & saber or jig saw, depending upon the thickness and complexity of the cut. I have developed my own speed & feed technique with two-flute end mills or blade tooth pitch similar to what I would use for aluminum, and my feed rate is between two to three times that which would be used for cutting aluminum. Once you start a cut, you have to just keep going without hesitating once you have found a comfortable feed rate. A router or rotating Dremel tool should work, but the super-high RPM's would make the needed feed rate higher than I would want to try by hand. I would think that with a good speed controller one could get good results. If you want to calculate where to start, figure somewhere between 1 & 2,000 surface ft per minute cutter speed, and no more than .010 in. of feed per tooth. For example, if a round cutter is used, try: rpm = 4 x sfpm/dia. This should give you an idea of how fast to feed thru the plastic at various RPM's. You can approximate the surface feet for saws and it should work just as well. Chris > {Original Message removed}

I used to do this way back when.... Use a bandsaw to cut it out a little over sized (you can cut several clamped together sheets at one time, depending on your blade), then use a 1" vertical belt sander to fix/smooth the edges. To keep from scratching it, leave the plastic sheets on it until your done sanding it. When sanding, sand edge at 90 degree angle from flat surfaces (perpendicular) hard enough to get off any edge cracks from bandsawing. Then sand at 45 degrees from both sides, then run "very lightly" (on part of belt sander that has no steel backing) at 90 degrees again (perpendicular) to get rid of residual flashing. {Original Message removed}

>This is the first time I've heard of a blade with >teeth on both sides. I need to go search for this. >Do you have a source for this blade? I would guess >that it has very fine teeth? I have a blade like this that came in a Black and Decker blade pack that I got for my jigsaw. I cannot recall what it is described as, but it has quite coarse teeth, i would say about 6/inch. It may be worth seeing what is in a blade pack at your local DIY. My experience is that there are not many staff who have real knowledge of what advice to give when you start asking these sort of awkward questions. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Hi Neil, ring around the local signwriters, they almost all have CNC flatbed machines set up for acrylic which they do all day every day. If you take in your acrylic and a decent drawing they can cut your shapes neat and exact in whatever quantity you need. The operator is usually skilled enough to whip up basic geometric shapes in minutes, although they may ask you to leave the job until off-peak. For a few small pieces they'll probably charge about $10. :o) -Roman Pic Dude wrote: {Quote hidden}> > Looking for suggestions on making smoother curved cuts in 1/8" and > 1/4" acrylic. urrently I use a Dremel rotary tool with a Roto-zip type > cutting bit (rotary/spiral saw bit) but get very jagged edges. > > Anyone know if there a better bit I could use for this? Perhaps a > Dremel 194 high-speed cutting bit would work better? > > Or is there another process I could use for this? Scoring/snapping > and circular saw with carbide-tipped bit are the only other processes > I know for this, but they are just for straight cuts. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Lots of options here, so I need to start experimenting. The curves will be fine, and I intend to make a jig. The options I have are now many: - Heated wire -- need to locate proper wire. Power supply etc is easy to get, but will need to experiment with settings. - Router/dremel with appropriate bit -- easiest to start with since I already have one. Two bit options are now available to me. - Jig-saw or equiv -- need to find the right bit. I'm avoiding sanding, etc cause I will be making multiple copies of a piece and want to make it a repeatable process vs. say, an art. :-) Thanks for the options everyone -- I now have my homework to do and will let you know what the outcome is. Cheers, -Neil. {Original Message removed}

----- Original Message ----- From: "Alan B. Pearce" <.....A.B.PearceKILLspam.....RL.AC.UK> > > I have a blade like this that came in a Black and Decker blade pack that I > got for my jigsaw. I cannot recall what it is described as, but it has quite > coarse teeth, i would say about 6/inch. Yep that's the one I use came in the same pack. Seems to work well with thicker lexan and other plastics not sure how well it would work on thinner stuff though. When I first tried this I was cutting about 15mm thick soft poly-something-or-other sheet. I carefully marked things out got out my Jigsaw and made the cut great! Then I tried to push the section I had cut out of the surrounding material it wouldn't move the cut had effectively self healed behind the blade! Must say that next time I have much of this to do I may take up the idea of visiting a local sign maker! I build model r/c subs for a hobby (hence all of the plastic cutting). I often end up buying things like servo activated air valves, lexan tube, pumps etc. I've always found that once you tell the guy (and it always seems to be a guy!) behind the trade counter what it is you are doing they go way out of their way to help you, much more so than any profit they are making would justify. Often doing stuff for free. I guess it just makes a change to get a request for something out of the ordinary. A bit like the piclist I suppose people just like to help when they can! Andy -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Andy Shaw wrote: {Quote hidden}> > ----- Original Message ----- > From: "Alan B. Pearce" <A.B.Pearcespam_OUTRL.AC.UK> > > > > I have a blade like this that came in a Black and Decker blade pack that I > > got for my jigsaw. I cannot recall what it is described as, but it has > quite > > coarse teeth, i would say about 6/inch. > > Yep that's the one I use came in the same pack. Seems to work well with > thicker lexan and other plastics not sure how well it would work on thinner > stuff though. When I first tried this I was cutting about 15mm thick soft > poly-something-or-other sheet. I carefully marked things out got out my > Jigsaw and made the cut great! Then I tried to push the section I had cut > out of the surrounding material it wouldn't move the cut had effectively > self healed behind the blade! > > Must say that next time I have much of this to do I may take up the idea of > visiting a local sign maker! I build model r/c subs for a hobby (hence all > of the plastic cutting). I often end up buying things like servo activated > air valves, lexan tube, pumps etc. I've always found that once you tell the > guy (and it always seems to be a guy!) behind the trade counter what it is > you are doing they go way out of their way to help you, much more so than > any profit they are making would justify. Often doing stuff for free. I > guess it just makes a change to get a request for something out of the > ordinary. A bit like the piclist I suppose people just like to help when > they can! > > Andy One word of caution is in order here. I do a bit of woodworking and occasionaly need to cut plastics like Lexan with a power tool. You have to be *very* careful because this stuff will splinter and kickback and cut you badly if you don't stay out of the way of the direction of travel. Also, when these plastics are cut or milled, they emit a gas which is very bad news. If you must cut this material, I strongly recommend moving the cutting machine outdoors if possible and avoiding inhalation of the resultant fumes in all cases. -- ------------------------------------------------------------------------------ Tim Daneliuk @spam@tundraKILLspamtundraware.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> Lots of options here, so I need to start experimenting. > The curves will be fine, and I intend to make a jig. > > The options I have are now many: > - Heated wire -- need to locate proper wire. Power > supply etc is easy to get, but will need to > experiment with settings. Don't bother - hot wire doesn't remove waste and you'd need the wire insanely hot to make any progress, with the added side-effect of monomer fumes. I tried it once and what a messy job it did. The cut will seal behind the wire even worse than a bad blade and the molten plastic makes a ridge. Hot wire is only suitable for a limited range of materials, like polystyrene foam -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

FWIW, I have watched the shop next door cut stuff for me, and they use a 1/8 " dia., 1" long carbide flush trim bit in a router. A high speed router. Seems the best way. They use a template or guide. I have used jigsaws ( a pain) , Bandsaws ( also a pain and dangerous), a dremel tool with saw blade ( slow, messy and not very accurate) and a small dremel router( worked great, but slow). Good luck, and as noted before, be careful, wear safety gear, and use lots of ventilation. I also recommend cutting jigs, and gloves, because the stuff can bind and whack your fingertips. Not that I have ever been that clumsy. Er, at least not more than a few times. M. At 09:40 AM 5/16/02 +1200, you wrote: {Quote hidden}> > Lots of options here, so I need to start experimenting. > > The curves will be fine, and I intend to make a jig. > > > > The options I have are now many: > > - Heated wire -- need to locate proper wire. Power > > supply etc is easy to get, but will need to > > experiment with settings. > >Don't bother - hot wire doesn't remove waste and you'd >need the wire insanely hot to make any progress, with >the added side-effect of monomer fumes. I tried it once >and what a messy job it did. The cut will seal behind the >wire even worse than a bad blade and the molten plastic >makes a ridge. Hot wire is only suitable for a limited >range of materials, like polystyrene foam > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email spamBeGonelistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email TakeThisOuTlistservEraseMEspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

> And be particularly careful that you don't lose any fingers. > > Best regards, > > Spehro Pefhany Oh, he'll be alright. Look, I can count on one hand the number of fingers I've lost through industrial accidents. Or I used to be able to You might want to think about safety glasses though, especially with any high speed rotating tools like a router -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

> How's that go? "Don't look into LASER with remaining eye...?" > Actually, you've reminded me of laser or water jet cutting. I've got some acrylic components that I need cut out and had intended to check out the local company to get a costing. I think this will be a better option than molding or milling for the shapes and quantities I need Some years ago a friend had acrylic boxes fabricated and square holes cut for switches - he reckoned it was reasonably cheap after the set-up costs. I've got one of the boxes here and it looks like a pretty good job, clean and accurate cuts -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservEraseMEEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

Yes, If you 've got a laser cutter company somehwere near that is the best way. Reminds me of an 8085 assembler project I did many decades ago. We demo'd a laser cutter system for GM by cutting through 2" thick Plexi. Made a perfect circle with a gantry type XY system. Was given the project on a Friday, worked all weekend on it and demo'd on Tuesday. Too cool. John Dammeyer Wireless CAN with the CANRF module. www.autoartisans.com/documents/canrf_prod_announcement.pdf Automation Artisans Inc. Ph. 1 250 544 4950 > {Original Message removed}

>Some years ago a friend had acrylic boxes fabricated and >square holes cut for switches - he reckoned it was reasonably >cheap after the set-up costs. I've got one of the boxes here >and it looks like a pretty good job, clean and accurate cuts I knew someone who was into making stereo amplifiers for the "high end market" and they had black Perspex laser cut for them. The front panel push buttons were done by cutting a square in the Perspex, but one side was not cut the whole length, and became the hinge point for the button. I saw one of these panels, and the laser cut was real fine. I believe about the only thing that is difficult to cut with a laser is aluminium, because the melting temperature and thermal conductivity is such that the molten metal will not flow away and solidifies in the cut behind the laser. :) -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestspam_OUTKILLspammitvma.mit.edu