Grabbed a worn endmill thinking it would still cut clean, and it chattered so bad it trashed a $300 part

I was running a job on a Haas VF-2 in Phoenix last Tuesday, and I swapped in a used 1/2 inch carbide endmill I'd sharpened twice already. About halfway through a pocket in 6061 aluminum, the tool started squealing and left a surface finish that looked like a damn washboard. Has anyone else pushed a tool too far and regretted it?

3 comments

3 Comments

drewr151mo ago

You ever have a buddy who swears he can squeeze one more pass out of a dulled up tool? My friend Dan did that on a Bridgeport last month, pushed a beat up 3/8 endmill through some 4140 and it snapped clean off. Scared him so bad he almost dropped his coffee.

elliotm571mo ago

Bet Dan's gonna think twice before trying to squeeze blood from a stone again. Nothing wakes you up faster than a carbide grenade going off in the middle of your shop.

elliotm571mo ago

...and that's exactly the kind of thing that makes me cringe every time I hear someone say "she'll hold together just fine for this one." I've seen a guy try to run a dull 1/2" rougher through some stainless and it started grabbing and chattering so bad you could feel it in the floor. Then when it finally let go, the whole work piece got yanked out of the vise and flew across the shop. Dan got lucky he just snapped the endmill and not his wrist or worse, because that 4140 doesn't give a damn about your "one more pass" plan. I swear, some guys treat tooling like it's a favor they're doing for the machine instead of just swapping it out and saving the headache.