Ran a $400 titanium part into a vise jaw because I skipped a tool offset check

Been running CNCs for about 4 years now and I always thought I was good about double checking offsets before hitting cycle start. But last Tuesday on a rush job I had a new tool I just popped in and assumed the numbers were right from the previous setup. First pass at 12k rpm and 200 ipm and I watched that endmill plow straight into the jaw face. The operator before me had left a different tool height in memory and I never verified. That $400 part was scrap and I spent 3 hours dialing everything back in. Anybody else learn this lesson the expensive way or am I the only one who got too comfortable?

2 comments

2 Comments

jenny_jackson10d ago

Honestly, you're far from the only one who's been burned like this. A simple solution is to make it a hard rule that every tool gets a quick touch-off on a known surface before the first run, even if you think the offsets are good. It takes thirty seconds and saves three hours of rework.

kelly.parker10d ago

OH man, this reminds me of when I was helping a buddy set up his new mill and he was SO confident his tool presetter was calibrated perfectly. He ran a whole batch of parts before checking with a test indicator, turns out the presetter was off by like .005 because of some dried coolant gunk on the reference surface. We ended up having to scrap half the batch and start over, which cost him way more than the ten seconds it would've taken to just touch off on a gauge block first. Now I've got a rule for myself: I'll touch off on the same piece of scrap every time, even if I just ran that tool five minutes ago. It's a little obsessive but at this point it's just muscle memory.