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My old boss said to never dimension to hidden lines in a view
I thought it was just his personal quirk, but it bit me hard on a recent project for a machine shop in Dayton. The shop foreman called because a part was off by 0.03 inches, and the error traced back to a dimension I pulled from a line that was obscured in the section view. Has anyone else run into a rule like this, or was my boss just overly strict about one thing?
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the_rowan2mo ago
That 0.03 inch error in Dayton is a perfect example. Your old boss was right, it's a solid rule. Hidden lines can shift based on how the model is cut or viewed. I've seen similar issues cause scrap parts. Always dimension to visible, solid geometry.
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foster.tessa1mo ago
@phoenix_bailey you're right that three hundredths is the worst kind of error. Back in '98 I had a job in Toledo where a 0.02 inch hidden line shift turned a run of 200 aluminum brackets into scrap. The print looked fine at first glance. The machine shop cut them all before anyone caught it. My boss back then had the same rule as your old boss. Dimension to solid edges only, period. I still follow that rule today and it's saved me a lot of headaches.
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phoenix_bailey2mo ago
Wait, that error was only three hundredths? Honestly that's terrifying. I've seen way bigger shifts from hidden lines before but that tiny amount is somehow worse. It's small enough to pass a quick check but still completely scrap the part. Tbh that's the kind of mistake that keeps me up at night. Your boss's rule is the only safe way to work.
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