Found a 1970s drafting manual in a Seattle library that says we used to dimension everything to the nearest 1/64th

Pulled it off the shelf on a whim. The detail was insane, way tighter than any modern spec I've seen. Makes you wonder if all our CAD precision actually made us lazier. Anyone else run into these old-school tolerance rules on a retrofit job?

4 comments

4 Comments

susan_adams2mo agoMost Upvoted

Yeah, that bit about CAD making us lazier hits home. A buddy of mine was fixing up an old factory conveyor system, and the original prints from like 1962 called for some wild fit. He said they had to hand-scrape a bearing seat to get it within a couple thousandths, no machining marks allowed. The old guys who built it basically did watchmaker work on industrial gear. His whole crew was sweating it, while the original install notes were just like "step 14: achieve smooth blueing pattern.

adams.uma2mo ago

Just reading that gave me hand cramps (and I wasn't even holding a scribe).

the_wendy1mo ago

God, that's exactly the kind of thing that makes me nervous just hearing about it. My buddy Tim had to do something similar on an old planer mill. The original hand-scraped ways were still in spec, but he had to touch up a worn spot on the saddle. He spent three whole weekends with a carbide scraper and bluing ink. Said his hands shook for a week after. The worst part? The original guy probably did it in an afternoon.

bettym112mo ago

Wait, they had to hand scrape to a smooth blueing pattern on a factory machine? That's next level. I can't even get my saw blades that perfect. Makes you wonder how many months some of those old builds took.