Where to Find Tolerancing Resources for Mechanical/Design Engineers
Where to Find Tolerancing Resources for Mechanical/Design Engineers
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Where to Find Tolerancing Resources for Mechanical/Design Engineers
Where to Find Tolerancing Resources for Mechanical/Design Engineers
Quote:
Your education can’t always prepare you for everything that may happen in your engineering career. You’re working on a project and everything is running smoothly when you realize “I don’t know how to tolerance this part!”. You know you need some reliable information but you don’t know where to turn.
Luckily for all of us, the Internet can bring us together to learn beyond the classroom on websites like Eng-Tips Forums....





RE: Where to Find Tolerancing Resources for Mechanical/Design Engineers
Eventually, what a design can tolerate is a money problem, though it may detour through a stress problem on its way to being a money problem.
Another distraction is that of fit problems, but that's a combination of an apportionment problem with a cost problem on top of it. If car parts were made to nanometer level accuracy for cheap, most all parts could have nominal fits and they would go together.
RE: Where to Find Tolerancing Resources for Mechanical/Design Engineers
RE: Where to Find Tolerancing Resources for Mechanical/Design Engineers
As was stated above, in general tighter tolerances really mean a lower level of engineering. The real idea for any engineer should be to design parts that will perform their intended function for the lowest possible cost.
RE: Where to Find Tolerancing Resources for Mechanical/Design Engineers
Another thing is that cost is frequently stair-stepped relative to the tolerance; wide bands of tolerance can have exactly the same cost. On any of these stairs, the smaller value will result in less variation in the final product and less variation in performance.
Some of the most expensive parts to use I've come across are the ones that are the lowest cost to make.
RE: Where to Find Tolerancing Resources for Mechanical/Design Engineers
Engineers who say "make it to the print" and lazily walk off don't last, because if we need 8 pieces, only 8 get produced. There usually isn't time or money for scrap and starting over or changing manufacturing processes. This forces the conversation of what process was used, what tolerance was achieved, and is compared to what tolerance will really actually succeed. The drawing tolerance in most cases was a reasonable guess on all of those things up to that point.
We try to stick to common manufacturing methods: milling, drilling, water/plasma/laser jet cut profiles, turning. Key features may have an analytical tolerance based on engineering reasoning, others have tolerance based on reasonable judgment. Most all tolerances could be better - but most of those also have very little return on investment. The key is to get out there in the assembly area and with the component manufacturing centers and find the pain points. Tighten up tolerances if assembly is not going cleanly, open up tolerances if component manufacturing is having trouble, learn how the part is being made and used and adapt the design where possible. If the part is made by outside vendors, now the conversations and discovery must occur several times and the feedback must be aggregated.
David