GD&T

[ctopher]

A few years ago I came across an Excel spreadsheet that you can take two parts and type in the dim's with tolerances using position, runout, etc. It gave you a tolerance number to use. I can no longer find it. Has anyone seen it or has anyone created one on your own? If so, can I get a copy? I am going to attempt to create a spreadsheet that is linked to design tables of parts for users to do GD&T. Thank you
ctopher

 

[drawoh]

ctopher,

Are you talking about the ISO tolerance letters?

Numerical tolerances are based on your application, not just the dimensions.

JHG

 

[ctopher]

All of GD&T in general

 

[drawoh]

ctopher,

I am not sure of what you mean by a tolerance number. Are you talking about the actual tolerance value?

JHG

 

[ctopher]

yes

 

[drawoh]

ctopher,

Your tolerances are based on your requirements. For positional tolerances for screws through holes they are

Floating: holeMMC - screwMMC

Fixed: (holeMMC - screwMMC)/2

For everything else, you need to know what kind of fit you want. The ANSI standard fits in the Machinery's Handbook are a good start. There is a page showing what manufacturing process achieve the fits. You do not want to weld to +/-.0001" if you can help it.

JHG

 

[ctopher]

Thanks drawoh. But I am looking for the spreadsheet I had seen before or if someone had created one in Excel. Just insert tolerances from mating parts to come up with GD&T on a dwg.