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I am looking for calculator or chart for slip fit and press fit for non standard size parts.

For example, I have oversized dowel pin 10mm +0.03/+0.01 diameter. I need to create a slip fit hole for that oversize dowel pin. What the size and the tolerance of the hole should be?

Another example is I have an undersized plastic bushing which diameter is 20mm -0.05/-0.02 diameter. I need to create press fit hole for that bushing. What the size and the tolerance of the hole should be?

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  • $\begingroup$ Slip fit is heavenly dependant of you application and its friction values. When the CoF is really important here, i would recommend testing. If you know how tight or how much clearance you require, you can calculate your fit. Hence I/you need a bit more context to answer you question. For (ISO)fit size determination i frequently use fit calculator & info. $\endgroup$ – SimpelenLeuk Oct 29 '16 at 17:52
  • $\begingroup$ You have to measure your dowel pin with a micrometer first, whatever the micrometer reads just add .0005 inches to .001 inch to that reading and that is the size reamer you need to ream your hole for a slip fit. Press fits are a little trickier because it is material dependent to determine how much interference you want ( and how much force you want to apply to force the pin into the hole). $\endgroup$ – William Hird Nov 28 '16 at 15:50
  • $\begingroup$ Before you start specifying hole/shaft tolerances, you need to define the function of the fit. Do you need a running clearance? Asliding fit where the parts can move, but are not free running? Is the fit definging location? How precise does the controlled location need to be? How much slop in the joint is acceptable? How tight does the press need to be? Do you need a shrink fit? A light press? There are a good 25 pages in Machinery's Handbook on designing fits, not including fastener clearances, with the information you've provided, all I can suggest is to read those pages or use Google. $\endgroup$ – DLS3141 Feb 27 '17 at 16:40
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You will need to decide what standard you want to base your estimates off of and the level of tolerance. There is also the expense and manufacturability to consider. Here is a calculator I found. The site has others as well. I am sure an internet search will lead to other calculators and guidelines:

https://www.engineersedge.com/calculators/mechanical-tolerances/ansi-fit-tolerances.htm

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I think, unless you are planning for mass production, you need not search for any standards.you can experiment and decide the values yourself.(Iam not sure about this suggestion.But from what I learnt IT grades are used in mass production of hole shaft assemblies because machining cannot be done precisely and identically for all the parts.In case of single components, I think its not needed)

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