cnc_works
06-06-2013, 07:24 PM
So, I'm cutting copper, unknown alloy but hard to cut with a knife. .1" thick, out of a 24" x 36" sheet, a Chinese character about 12" square. I have to use a 1/8" bit to get into the corners.
First try was with my go to bit, Onsrud 63-712...I know it is a plastic bit, but I've cut a lot of aluminum with it. 7000rpm, 20ipm, .025 depth of cut. Air for cooling, but no lubricant. It cut about 3" and broke. Made a kind of grinding, juttering sound.
Ordered a 63-606 designed for non-ferrous metals and it began making a somewhat similar sound, so I chickened out and stopped before it broke.
Called Onsrud, he said I'd be better off to cut a clearance cut with 1/4" and do a clean-up cut with the 1/8". Tried that with a 1/4" Onsrud 63-725 with air & lube still using the .003" chipload, 7000rpm, 20rpm, .025 depth of cut with a constant ramped cut. As soon as it reached full cutting depth of .025" the it made the same sound.
Tried speeding up the spindle some, maybe 10K, but samo samo. Researched the forum, didn't find too much to help. I experience no other problems with my bot, cutting aluminum, hardwoods, plastic.
Soooooooooo, any ideas?
First try was with my go to bit, Onsrud 63-712...I know it is a plastic bit, but I've cut a lot of aluminum with it. 7000rpm, 20ipm, .025 depth of cut. Air for cooling, but no lubricant. It cut about 3" and broke. Made a kind of grinding, juttering sound.
Ordered a 63-606 designed for non-ferrous metals and it began making a somewhat similar sound, so I chickened out and stopped before it broke.
Called Onsrud, he said I'd be better off to cut a clearance cut with 1/4" and do a clean-up cut with the 1/8". Tried that with a 1/4" Onsrud 63-725 with air & lube still using the .003" chipload, 7000rpm, 20rpm, .025 depth of cut with a constant ramped cut. As soon as it reached full cutting depth of .025" the it made the same sound.
Tried speeding up the spindle some, maybe 10K, but samo samo. Researched the forum, didn't find too much to help. I experience no other problems with my bot, cutting aluminum, hardwoods, plastic.
Soooooooooo, any ideas?