Old timer told me to stop chasing tenths and it saved my sanity

Been running a Haas VF-2 for 4 years now and I used to tweak offsets by 0.0002 every time a part was off. Old guy named Pete at a shop in Newark pulled me aside last March and said I was chasing temperature swings, not tolerance. He was right, my shop temp varies by 8 degrees over a shift and I was fighting a losing battle. Anyone else get told to loosen up and found their parts actually got more consistent?

3 comments

3 Comments

rosepark15d ago

You ever catch yourself adjusting offsets just because the numbers moved, even though nothing else changed? @hernandez.gavin pretty much nailed it with the "cutting in the same air twice" thing. I had an old-timer tell me to watch the chip color and sound more than the readout once the machine is warm. If it's cutting consistent chips and the finish looks good, that 0.0002 might just be the barometer changing. Also, get a decent digital thermometer and map your shop floor temp changes. Then set a window for your offsets so you're only touching them when a part drifts outside that range. It's weird how letting go a little actually makes things more reliable.

johnson.eva15d ago

That chip color and sound advice is gold, most guys overlook it. But I gotta gently push back on the digital thermometer thing a little. You don't REALLY need a fancy one, just a cheap dial thermometer hung by the machine is enough to see the swings. I had a $5 one from Grainger taped to the side of my VF-2 for years and it told me everything I needed to know. The key is knowing WHEN the temp changes happen, not the exact number. Pete probably would've laughed if he saw me with a digital thermometer anyway, he was more of a "feel the casting with the back of your hand" type.

hernandez.gavin15d ago

Eight degrees over a shift? That is wild. I can't believe you were trying to hold two tenths in a shop that moves that much. That's like trying to glass bead a part in a hurricane. Old Pete did you a real favor. I had a similar moment with a guy named Dave who told me to stop checking everything with a micrometer and just make sure the machine is cutting in the same air twice. It changed my whole approach. You were probably chasing air temperature changes in the coolant and the casting, not even real problems with the tool or the program.