Thanks all for comments. Looking forward to doing some more work on this but will be another week or two before I have any more to show...business travel coming up right thru weekend. At least I'm headed to Orlando where it's a bit warmer!
Quote:
Originally Posted by will916691
for a .015 endmill you want to try and stay around .0075 depth of cut a good rule is half the dia of you endmill smaller depth of cut will be less stress on the endmill what did you work out with your speed and feeds?
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Will - Thanks. I did finally find a good source for these calculations and that's pretty much what I learned...no more than 1/2 endmill width for DOC. For the bottom grill plate with STERLING letters I had no problems. I used a .037 2 flute endmill w/ .01 DOC at 3IPM w/ 10,500 RPM spindle. I have since read that I should have been running about 10 IPM to keep from burning up the bit. I was hesitant to run that fast for fear of bit snapping. ?? On S relief pocket for the main grill I was going with the .015 endmill and went for same .01 DOC and the bit snapped almost immediately. Having not learned my lesson I loaded a .025 EM (not what the CAM file called for but figured it would be fine for test) and...same thing. Wha?? I ended resetting the Z axis height and cutting the S relief with the broken .025. LOL. As it turns out I had accidentally ordered standard length mini bits instead of stub. I think stub might have handled the .01 DOC but I'm staying under 1/2 endmill width for DOC from now on!! The correct miniature stub endmills have been ordered so I have high hopes for next set of parts.
Any thoughts on this next issue would be appreciated as well. I also had problems with slightly bigger end mills (more rookie stuff). Cutting the slots for the main grill with a .0625 2 flute EM (still at 10,500) w/ DOC .03 and Feed at 3IPM things looked real nice for about two or three slots then started looking rough...then real rough, then SNAP. I actually did the same thing with a .125 EM the night before cutting profiles out. After digging in to some metal cutting reading I'm pretty sure the issue was that I was actually running too slow on feed rate and overheated the bit causing it to clog w/ melted chips...calculations I have since found say at least 10 to 15 IPM at these spindle RPMs to keep from overheating or dulling. I kept slowing the feed rates down when I had problems and I think that was opposite of what I should have been doing. Looking forward to testing this theory and will probably slow the spindle down for .0625 and larger endmills. Thoughts?
Joe