Hackaday: When designing parts on a screen, it’s very easy to type in a bunch of nice round numbers and watch everything slot together in perfect harmony. Unfortunately, the real world is not so kind. A 10mm shaft will not readily fit in a 10mm hole, and producing parts to perfect dimensions simply isn’t possible. This is where fits and tolerances come in, and [tarkka] have created a practical demonstration of this on Youtube.
2 comments:
I don’t deal with tolerance that much anymore since scenery tends to just assume give or take 1/16th, but back when I was quality control on my high school robotics team, I was basically in a constant state of trying not to scream at the designers about tolerances. Because we were a bunch of teenagers, we didn’t really know what we were doing, and so people would constantly design parts and then slap a +/- .001 tolerance on the drawing as if it is reasonable to expect a bunch of high school students to machine that precisely at all, let alone in a timely fashion. It made QC take forever because I basically just had to go to every designer and tell them the actual dimensions on each part and then ask them if it actually mattered or not. And often even though it wasn’t in the listed tolerance, it was actually fine. Often times it wasn’t though, because people weren’t designing parts to not need to be precise (ex: drill holes to match when assembling rather than machining plates separately, slots instead of holes, etc.) Definitely wish I could’ve had everyone watch this video back then.
I’ve never had to deal with tolerance, but I know that I will as soon as we start Rube. This is definitely a stressor in my life, because I’ve never dealt with it before and I’m not sure how to prepare for it. Luckily, this article has helped me identify how to plan the fabrication and planning of allocation of supplies without being too nit picky. Hopefully, I’ll be able to estimate correctly with the help of my teammates even thought I’m still not exactly sure what I’m doing. I’ve been in plenty of crew calls where everything is stopped by scenic because a piece wasn’t built completely correctly. Having to prepare for errors, both big and small, are part of tolerance and should also be calculated based on crew skill level. I remember building trusses for Figaro, and we, the freshman, were trying to build them to fit together perfectly. We took so much time that one of the graduates had to come in and do it for us. He did it in a quarter of the time it took us and everything turned out okay because of allowances.
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