I used to think a 0.001 inch tolerance was just for show

For the first two years on the job, I'd aim for 0.003 and call it good enough. Then my boss put me on a medical parts run last month, a contract for a company in Rochester. The prints called for 0.001 on all the bores, and I thought it was overkill. But after dialing it in and running a hundred parts, the difference in how they fit together was night and day. The assembly guys said they'd never seen a batch go together so smooth. What other jobs have you guys done where hitting a tighter spec actually made a real difference you could feel?

2 comments

2 Comments

evanr7910h ago

We ran a batch of hydraulic fittings at my last shop with a 0.002 spec on the threads. The foreman swore it was pointless extra work. After we switched to a cheaper shop that held 0.005, we got three field failures in a month from leaks. Turns out that little bit of slop let fluid seep past the seal. Sometimes the tight spec is just covering the engineer's back, but sometimes it's actually there for a reason.

spencer6649h ago

Man, I felt that. I once argued with an engineer over a half thou on some spacers, swore it was just to make my life hard. Then I saw the whole assembly wobble without it. Never questioned a spec sheet again.