Extruded Acrylic

[bleeth]

Been doing plastic signs lately and got a deal on some 1/2" extruded for the punch through letters.
First time I did extruded and sure had issues at first. I used single flute O flute and cut at 8k RPM and 1"/sec. No extra cooling. The bit was an up cut 3/16D (Onsrud). For cast cut with same bit but faster on RPM and speed. Up-cut fights holddown but gets more plastic out of the way.

[navigator7]

Richard wrote:
"I was going to mention as well there are different types of plastic. "

Richard, what is the brand of some carve able plastic you know?

Bill's problem reminds me of issue I had turning UHMW in a large manual lathe.

We were making rollers for the phone company and these chips wanted to reach out and touch somebody.
I once had a chip reach out into a previous pile, suddenly snag and I had a ball of UHMW as big as a four or six yard dumpster attacking the lathe chuck.

We later sent some UHMW to a cnc shop and discovered the CNC machine had a "peck" feature. The machine would cut and stop and the air blast kept the cutting area free. Only tiny little chips were produced.

@ Bill,
You said the plastic machines like chewing gum?
What about using dry ice to give the plastic some chill?

[rb99]

I am not sure. I have seen extensive spec sheets from GE Plastics though. I bet a search would yield something, or talk to your plastic suppliers about what works.

RIB

[bill]

As they say "spilt milk under the bridge" er sumfin' like that... the job is done, delivered and a happy customer.
For now, in belief that it was a bad batch of acrylic with consistancy at fault (fingers crossed). The next time will bid higher on this brand of material just in case. I am going to set up for cooling air as well. Want to thank all for your help! Vortex (tooling) suggested the straight, 2 flute O flute to try and prevent the wrapping issue. Have off-cuts to experiment with once the straight O flute tooling gets here and will let all know what becomes of it all.
Once again, Thanks to all.

[navigator7]

Never heard of O flute so I googled it:

http://www.toolstoday.com/p-5879-sol...-down-cut.aspx

[clueless]

I cut some extruded, although it was 1/8", but used a 1/4" O-flute, single flute. Cut very nice and left a decent edge as well.

[bill]

... just give an initial close watch if the material is brand named Evonik Ind. by Cyro Ind. That's the only extruded material brand I have had problems with.

[carlcnc]

Bill
could yu share source /techniques for the led strips that you use?
thanks
Carl

[magic]

Is it possible to do some of the perimeter cutting on a table saw>

[jerry_stanek]

what bits are you using to engrave the clear acrylic?