Had a talk with a guy at the tool sharpening shop that made me rethink my offsets

Last Tuesday I dropped off a few dull end mills at Hendrickson's Sharpening in Dayton and got to talking with the owner, Mike. He's been doing that job for 30 years and he said most guys that bring in their tooling never check runout after a regrind. I admitted I never even thought about it because I just assume they come back perfect. He showed me a worn collet that was introducing .002 of wobble on a freshly sharpened cutter. That little conversation made me grab a dial indicator and check my whole toolholder setup. Now I'm wondering how many parts I've scrapped over the years just from bad holders. Has anyone else actually measured runout after sharpening or am I the last guy to figure this out?

2 comments

2 Comments

beth_hunt3d ago

Watched a guy at a job shop do the same thing with a collet that was older than him. He grabbed a tenths indicator and found out his main holder had .003 of runout at the nose. Swapped to a new ER collet and that same cutter ran true to .0002. That one change fixed chatter issues on a batch of stainless parts he was fighting for weeks. Check your end mill holders too, they wear out faster than people think. Sometimes the simplest fix is the one you overlook the longest.

dixon.daniel3d ago

Is it really the collet's fault though? I've seen guys throw brand new holders at a problem and still get chatter because their machine's spindle bearings are shot. You can put a tenths-holding holder in a worn out machine and it won't matter for crap. Plus, .003 of runout at the nose might be a symptom of the taper being dirty or damaged, not the holder itself. How often do you check the spindle face and taper before swapping tooling?