Ran a job with 0.001 tolerance on a 20 year old Haas and it actually held. Luck or skill?

I was out at a shop in Gary, Indiana last month doing a run of aerospace brackets. The print called for +/- 0.001 on three critical bores and I had to use an old 1998 VF-2 with worn ways. I babied the feeds down to 8 IPM and used a brand new 3/4 carbide end mill, but part of me thinks it was just dumb luck the machine didn't drift. My buddy swears you can hit those numbers with old iron if you take light enough passes, but the old timer next to me says its all machine condition and you're kidding yourself if you think operator finesse matters that much. Who's right here? Has anyone else held tight tolerances on a clapped out machine and felt like it was a coin flip?

2 comments

2 Comments

the_lisa7d ago

Nah man, I used to be on that old timer's side thinking it was all machine condition until I ran a part on a Bridgeport from the 80s that had 0.012 of backlash in the X and somehow held +-0.002 on a bore. That day I learned you can finesse a lot out of worn out ways if you're smart about climb vs conventional and take finish passes at like 5 IPM. I think the real answer is it's both, but skill matters way more than people give it credit for.

jenkins.wade7d ago

@the_lisa I gotta disagree a little man. Yeah skill helps but that 0.012 backlash is gonna bite you on the next part when the machine decides to act up. I've seen guys finesse tight stuff on old clunkers but it's not repeatable day in and day out. The real trick is not having to fight the machine in the first place.