tips on cutting plastic

[Alan m]

hi there
iv been cutting some cirlcles and curves out of plastic with my trion but im melting more than cutting.
i think its policarbonate
i often put it as inspection windows when im redoing the dc on my tools

i have tried speed up and down, rougher blade ,fine blade,.
the only way iv found is go really fast but thats not accurate enough.

have you got any tips on cutting it

thanks alan

 

[mouppe]

I have had the same problems as you are having when cutting plastic. My solution was to trim it close with a jigsaw, and then sand to the line. I wore eye protection and a respirator and I looked like I had been tarred and feathered by the end of it!

 

[tbellemare]

Plastic shavings/dust will remelt due to the heat generated. As always, it's a feed and speed thing.

The blade Festool recommends for the task is 486554. That should help some. I would slow the speed of the blade way down so that you can push the saw at a comfortable rate and not dwell too much.

I haven't cut plastic with a jigsaw but have cut a lot of it with other saws and routers and slowing the cutter way down is the trick for me.

Tom

 

[Alan m]

i tried the speed at on and the roughest blade i have. it still melts behind the cut

 

[Jesse Cloud]

I can suggest how NOT to cut plastic.  Don't use a bandsaw, unless you want to spend a long time cleaning the stringy fibers out of your saw. [scared] [eek]
Don't ask me how I know that. [embarassed]

 

[tbellemare]

I'm not positive, Alan, but I don't think you want the roughest blade. Below is an image of the S 75/4 FSG next to the HS 75/3 bi. The S 75/4 FSG is considered a fast cutting wood blade. The HS 75/3 bi is the blade for plastics.

[attachimg=#1]

There is a noticeable difference in the teeth.

Tom

 

[Alan m]

thanks tom.
i will look and see what i was using

 

[Jonhilgen]

If possible, try to cut it with a ts55 or skil saw.  When you are cutting plastic with a jigsaw, the width of the cut is such that it will melt back together behind the blade.  I had to cut a clear plastic vanity down and learned this the hard way.  After cutting with a skil saw or Ts55 then either route is with a straight edge to your finished dimension or belt sand as Richard suggested.  

Jon

Edit: it would help if I read that you were cutting circles....so disregard

 

[awdriven]

There are specialized router bits for cutting polycarbonate. Is that an option for you?

http://www.toolstoday.com/p-5879-solid-carbide-spiral-o-flute-plastic-cutting-up-cut-down-cut-router-bits.aspx

 

[fdengel]

I've had some success using crown-tooth blades in a scroll saw, for somewhat thin plastic.

 

[Alan m]

thanks jon
i would try the ts55 if it was straight. would the plastic ruin the blade (or take the fineness off the edge)

awdriven.
i dont really need the accuracy of the routerbit or the jigs jigs it would require.
most of the pieces are for the top of dc schrouds  and be siliconed in place

 

[Brice Burrell]

Alan, I bet a coping saw would work.

 

[Qwas]

Hi, Alan. I've cut plastic quite a bit with my Trion jigsaw and I don't have too much problem. Plastic can be finicky to get cutting just right.  The blade Tom Bellemare showed should work but I use a normal wood working fine tooth blade like the S75/2,5 or the S50/1.4K, just be sure it is sharp. You will have to play with the motor speed  but something between 1 and 4 should do and once you start cutting, don't stop and move as fast as you can without forcing the saw to cut. I've seen the plastic melt at motor speeds of 1 and 4 but be fine at 2 or 3.

When cutting plastic, friction is your enemy. The saw blade needs a good teeth set so the blade itself doesn't rub and cause friction. You need sharp teeth to stop friction there. When cutting a circle, make sure the back of the blade isn't rubbing on the plastic. If it is, switch to the S50/1,4K blade. You can also try a light coating of baby oil on the plastic before cutting.

 

[mattfc]

Alan, make me wonder whether the heat build up might be due to the jigsaw blade guides rather than the cutting action itself? maybe try loosening them right off and doing a test straight cut to see whether thats causing the problem

 

[Alan m]

thanks mattfc.
i will try that
the guides were not that tight but were properly adjusted.

qwas
i tried my festool ones (rough il find out the no) , dewalt rough, dewalt very smooth(very good finish on timber at times) , super fine (hiti ones), and metal cutting ones
all brand new and razor sharp.

i will try and lub it up and see.
i will try and find that sweet spot with the speed. i varied it but didnt try every speed variable

should the pendulam setting be on or off  and what no

thanks alan

 

[Qwas]

I didn't even think about the pendulum setting. Mine is always set on 1 and it rarely gets moved, so I would recommend 1.

I would rule out the metal cutting blades right away, too many teeth and the teeth aren't deep enough to pass out the plastic chips.

 

[GhostFist]

Try cutting a 4x8 sheet of 1" thick plexi on a cabinet saw (never mind just getting it up on the saw) if you want to talk about nerve racking. oh ya no splitter either, hows that for an exercise in stupid? It was years ago, cuts came out perfect but I was drenched in sweat after the whole thing. Never again!!

I've cut a lot of plexi Don't recall using a jigsaw on it but I must have done an ellipse or two just cant recall what I was using or my settings. been a long while, pre-festool for me so no tips just reminiscing from the peanut gallery

 

[Brice Burrell]

Try cutting a 4x8 sheet of 1" thick plexi on a cabinet saw (never mind just getting it up on the saw) if you want to talk about nerve racking. oh ya no splitter either, hows that for an exercise in stupid? It was years ago, cuts came out perfect but I was drenched in sweat after the whole thing. Never again!!....

Just imagine how easy it would have been with the TS55.  I couple of years ago I cut a piece of decorative polycarbonate for a front door.  This stuff was really cool, it had bamboo and little flowers in the center so the whole thing looked like some sort of flowering bamboo trees.  I was told the flowers were real.  If memory serves it was $1600 for a 4x8 sheet.  Super easy to cut with the TS55. [thumbs up]

 

[Alan m]

brave man brice.
i would be very nervious

 

[Alan m]

i was cutting more today .
i set the trion to speed 2 and pendulium 2 and used the 75mm /4 blade (i think )
i also used mattfc s  tip . i opened the guides up a bit wider than normal. the heat must have been coming from there . it was the same blade i was using before so it didnt get any sharper etc
it worked great. it is amazing on speed one it melted