I'm having bad luck machining pink foam. Using a mill with carbide end mills, running at about 1500 rpm. I'm leaving a lot of attached material and the walls are rough cut. Not smooth like the pink stuff Kelly has been been been been routing.
Sorry for your troubles. -Diameter and feed rate, depth of cut? -One or two passes? I have had pretty good success with 1/8" (3.2mm) and 1/4" (6.4mm) tooling on foam in my small CNC. PS My speeds are relatively high too, drywall router on a speed control, maybe 9k on the 1/4" and 12k on 1/8". Feeding 40-70 inches per minute.
Instead of 1500rpm, you need more like 15k-20krpm. Woodworking bits work better than those intended for metal cutting because the rake and gullet on the cutting edge cut and clear chips in the soft material much better. Need router speeds, not knee mill speeds. More flutes will help a little and all the speed you got. At 15-20krpm, two flutes are best. I use spirals. They cut the best. Best, Kelly
Yeah, after going back and looking at your pin router video, I can see that you are going at a much faster rpm. I need to set up a router with woodworking bits and try again. Thanks to both Tops and kelly for your responses! Much appreciated.
If you are using a mill and want to retain the use of you XY table, you could make a router mount that clamps to your quill. It would be a good lost foam casting project! Best, Kelly
I believe Kelly cuts all of his stuff in the conventional manner too, not climb milling. Or is it the other way around?
Always conventional on roughing and most everything else with upcut spiral flute cutters. Sometimes I'll do a full depth clean up climb cut, but with double flute spirals meant for foam cutting, it doesn't make a great deal of difference. Either way you'll never achieve what sanding with 220-320 grit abrasive will do, and it's quick and well worth it where it counts. Best, Kelly
