When you crash with that, you can mess it up , too,,,, right there where the inset is held.............. The biggest mistakes people make are, tool tip below center, tool not square to the work, too much or too little feed/speed, blade sticking out of the holder too far, not parting as close to the work holding (chuck or collet) as possible......
I see several RPM numbers thrown out, but no mention of the diameter of the part being cut. Diameter of the part is part of the calculation to determine what RPM you should be turning. SFM x 12 divided by (diameter of the part x 3.14) Common steels, like C1018, can be cut with HS tooling @ 100-120 SFM (surface feet per minute) = RPM. If you use carbide tooling, SFM can be increased by 3+ times that of HS tooling. There are plenty of on-line resources for SFM recommendations for the material you are working with. Parting is one place where SFM really matters. You need to know how fast to turn the spindle for the diameter of the part you are parting-off/turning/drilling/reaming to get the best results.
Most times your cut off blade isn't square to the work when this happens. I cut off 4140 Heat treated bar today w,/carbide insert&coolant at 250 rpm.That was where I messed up, not having enough relief.
I went back to the old school and lots of lube after trashing the insert style.
While all have an ear to this. I have a heck of time getting mine nice and square. Seems I always either go left or right with a taper or a crown.
Any tricks?
Jeff
Below center is death on a cut off tool. When bar grabs and climbs on top of cut off tool it's a hell of a wreck.Do not mis read this! This is the #1 mistake i see with machinist and part off tools.
Check with your tooling supplier when you order. My Iscar blades are supposed to be run 0-.007” ABOVE center.
Most tang grip inserted blades will give you fits below center. You will think its a rigidity issue but its not.
#2 mistake is feeding too slow. With proper sfm and feed. You should be able to bury that blade with no hesitating.
Carbide, on center and run it as fast as it will go. Keep the pressure on the tool. Most problems arise with too slow an rpm, off center tool, too light a feed, tool not rigid and no coolant or lube. For production work, I prefer the insert tools with flood coolant.
Run it fast and keep the feed going.