Have you tried cutting corrugated polypropylene plastic?

[Mayo]

I've cut some 1/2" thick corrugated polypropylene plastic on the shopbot but since I never tried it before, I got less than perfect results. The edges were kind of fuzzy looking. I was able to smooth things out with a file but I would rather not have the extra clean up step.

If I remember right, when I did this I used a two flute, 1/4" carbide down spiral bit.

I'm now trying to cut some 4mm corrugated plastic (Coroplast is one trade name). Ideally the best way to do this is to just have the pieces die cut but I don't have the $350 for the die, nor do I need a sufficient quantity (at the moment) to make it economically feasable.

Have you cut this stuff on your shopbot and how were the results? Any suggestions for getting a nice edge?

[billp]

Mayo,
I've tried the spiral "O"bits in acrylic, and HDPE, absolutely beautiful ,clean, cuts. A few companies are selling them now, ranging from Mastercam ( expensive-$37), to BAM tools (www.bamtool.com) ( medium $27), and now Grizzly has them too ( economical- $17). I have tried the first two, not Grizzly's yet though.The bit geometry seems to evacuate plastic easily, and with the HDPE my shavings looked like Ivory soap flakes. Bill P.

[dands50@hotmail.com]

Mayo,
I use coroplast all the time for temp signs like for political signs ect. but I have never tryed to cut them on the bot I normaly cut them with a razor knife and a template so I guess you could try doing a sandwitch of bottom layer 1/4" plywood then 4mm coropalast then a template 1/2" plywood top with the template fixed to be in the same place each time so your router bit would go around that as if a template for a rub coller bearing on a hand held router this should help keep the thin 4mm from tearing from the speed of the bit. Just a thought David in Wyoming P.S. Good Luck let me know how it works