araugh
09-05-2012, 10:05 AM
Whelp, just broke 2 bits by not learning from a mistake. I'm cutting many holes in some 0.190" 6061 aluminum and my bit breaks in the middle of one of the holes about 2/3rds of the way through. I feel the bit after shutting down and it's very hot.
I think about this and think that it's hot because my speeds are set incorrectly, so I modify my rates and try again, as I'm running the file I notice a slightly odd noise in it's travel right before it starts a few holes from where the bit broke last time. I stop the machine and realize why the bit got too hot previously with known good speeds for the bit. I knicked one of my holddown screws while traveling because my safe Z wasn't high enough. Just barely, just a TINY bit, but enough to smash the cutting edge of the bit so that it does a poor job and generates excess heat, then snaps the bit.
A stupid lesson that I should have been prepared for, but at least I know better now. I hope this serves as a decent cautionary tale to other newbies that don't use a vacuum hold down.
I think about this and think that it's hot because my speeds are set incorrectly, so I modify my rates and try again, as I'm running the file I notice a slightly odd noise in it's travel right before it starts a few holes from where the bit broke last time. I stop the machine and realize why the bit got too hot previously with known good speeds for the bit. I knicked one of my holddown screws while traveling because my safe Z wasn't high enough. Just barely, just a TINY bit, but enough to smash the cutting edge of the bit so that it does a poor job and generates excess heat, then snaps the bit.
A stupid lesson that I should have been prepared for, but at least I know better now. I hope this serves as a decent cautionary tale to other newbies that don't use a vacuum hold down.