Spent 8 months setting tool offsets wrong until a part crashed

I'd been running a Haas VF-2 for about a year and kept getting weird surface finish issues on aluminum parts. Thought it was just chip recutting or maybe my feeds were off. One day I had a 1/2 endmill let go and it gouged the part, which was a $400 piece of 6061 that I already had 6 hours into. Shop foreman came over, watched me touch off the tool, and immediately pointed out I was adding the tool length offset instead of subtracting it on this particular control. Felt like a complete idiot. Now I always double check my offset sign before the first cut, especially when switching between machines with different control generations. Anyone else had a bonehead rookie mistake that cost them a part before they figured it out?

2 comments

2 Comments

oliver2425d ago

lol dude I spent like 3 months on an old Mori Seki where the tool offset page had a weird quirk where if you didn't hit the write button twice it would default to a random value from a previous setup. Wrecked a $300 fixture plate before I figured that one out. The trick I learned is to always do a dry run with the rapid override at 5% and your hand on the feed hold, watching the Z move relative to the part. Also helps to write your offset values down on a sticky note next to the control at the start of every shift, old school but it works. That Haas thing with adding vs subtracting is brutal because the screen looks exactly the same either way.

rubyj115d ago

wait so were you adding instead of subtracting the whole time or was it just with that one control? because 8 months of doing it wrong without a crash is wild, like how did you not get a bad toolpath earlier? i had a similar thing with a Mazak where i kept forgetting the G43 offset was negative compared to the Fanuc i started on, and i trashed a $50 piece of delrin before i realized. those Haas controls can be weird about offsets compared to other machines, so what made you finally check your tool touch off procedure? like was it the foreman teaching you or did you figure it out from the crash?