Cutting soft foam

[bob buttons (Unregistered Guest)]

i have a project where i need to cut a pocket out of 4inch thick soft foam 2 inches deep so a product can be protected by the foam. i have a porter cable router and a shopbot but have had no luck cutting the pocket yet. i have various bits but they all pull and tear the foam instead of cut it clean. anyone that has any experience in this area that can shed some light on this would be appreciated. i assume the bit is very important to getting a clean cut. thanks in advance!!!

[billp]

Bob,
When you say "soft foam" it's hard to tell what the material is really like. Is it a rubbery texture as in furniture seats? If so most of the time that's cut with a sharp knife or an electric carving knife. Have you tried reversing the direction of your cut, as in clockwise versus counter clockwise? What about a bit that has more flutes, and less room between them? A 4 flute bit might work better than a 2 fluter..

[Brady Watson]

Bob,
I would advise using a 1/2" straight bit with a 2" depth of cut. Depot sells them (Viper brand I believe) for under $20.

I will assume that you are running PartWizard.

7691
Be sure that when you are cutting a female/inside pocket/cut into foam that you always run the tool in Climb Mill. If you want a nice clean edge on say, the outside contour of letters, you'd run Conventional.

I would recommend running your router at the lowest speed, probably 9 or 10k RPM, a move speed of 1.5/.7, a stepover of .375 and a stepdown of 2". You should be able to get a nice clean cut in foam at those settings. You will have to test it since I run a Colombo.

Hope this helps.
-Brady

[Brady Watson]

You beat me to it Bill!

-Brady