I have been working on designing something in SolidWorks for the first time, which involves several parts with surfaces that slide into one another. I am wondering if there is a table or a standardization in terms of the distance that should be left between metal surfaces with sliding parts. I assume this depends on the type of metals and the tightness of the fit (I'm using copper parts, and the pieces should be able to easily slide in/out of one another). Obviously you can't have a metal piece you want to insert into another metal piece with the dimensions of the fit and fitting being exactly the same, it would be a very tight fit. Whether you should make an allowance 0.001 mm or 0.1 mm of space in your dimensions is beyond me though. Any advice?