A few questions about cutting birch ply and UHMW
I can't seem to get my bits to stop screaming at me when I cut 1/4" birch ply. Full depth pass at 3ips and fluctuating between 11500 and 13000rpm adjusting to try to find the less sqealing Hz. I'm new to cutting so I error on the side of conservative with feedrate. I usually profile cut this 1/4" birch for those squirlly letter doorhangers that are popular. Am I just going waaaay too slow with my feedrate? Also some of the big radius corners are a little chattery where it looks like the bit skips down the wood. I've tried using compression mortise, spiral up, and downcut bits. I use screws for my hold down method with tabs.
On the UHMW, I cut some for the first time last night. I cut 65 parts out of a 1" thick piece using a new upspiral single O-flute bit from Centurion. All of the recommendations I've found said go 1.5-1.7ips at 18,0000rpm. I cut it in 2 passes and my first pass was .51 deep. THIS STUFF MAKES A MESS! GOOD GOSH! The bit was squealing at me at first and I lowered my rpms to about 16000 or so but it still had a good amount of squeal and a good amount of chatter on the smaller pieces I cut. I was using screws as my holddown and tabs. The chips on the first .51 deep pass packed into the groove pretty tight and looked like they were ejecting about halfway out of the groove. This is a no-no, but I tried to rake out the chips from the first pass as the machine was going around for the second pass thinking that there may be some rewelding happening, which really didn't happen. Should I feed faster or decrease my pass depth and feed faster?
So, any suggestions? Thanks guys.
2006 PRTalpha 96x48
3hp SEV spindle
Vcarve Pro8
Always eager to consume large amounts of info, tips, and techniques!