Chatted with an older drafter about manual dimensioning, now I'm questioning my CAD habits

I was talking to a guy at a local drafting meetup in Portland who's been drafting since the board era, and he said that relying on auto-dimensions in CAD makes you lazy about understanding the actual geometry. He told me he still manually checks every critical dimension with a calculator to catch things the software misses. Has anyone else found that slowing down and verifying dimensions by hand actually saves them from redlines down the road?

2 comments

2 Comments

blake_cooper18h ago

That old-school drafter has a point but I think the bigger issue is how auto-dimensions can hide bad modeling habits. When you just click edges and let the software place numbers, it is easy to ignore that your actual geometry might be slightly off square or out of parallel. Manual checking forces you to look at the part as a whole system instead of just letting the computer slap numbers on there. I have caught problems where my sketch constraints looked right but some tiny angle was drifting because I never bothered to verify the math. It is more about building good spatial reasoning over time than just catching errors in the moment. The software will give you a number every time, but it won't tell you if that number is actually meaningful for how the part gets made or assembled.

keithbennett16h ago

Yeah totally agree with you on that. The software will happily dimension something but it won't tell you that your part is actually 0.0001 degrees off from parallel. I had a job once where a flanged bracket looked perfect on screen with all the auto dimensions lining up but once we put it on the assembly table nothing would seat right because the mounting face was just slightly twisted. Took me hours to find out the sketch had a tiny angle that the auto dims never flagged because they just measured the endpoints. You really gotta zoom in and check those constraints by hand sometimes. It's like the computer gives you the answer but doesn't teach you how to ask the right questions lol.