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Tolerance Calcs

Tolerance Calcs

RE: Tolerance Calcs

ctopher,

   You do realize don't you that the formulae for GD&T positional tolerances are very simple?  

   For a screw passing through a clearance hole into a tapped hole, the positional tolerances equal one half the diametral clearance, based on MMC values.  For a bolt passing through two clearance holes, the positional tolerances equal the diametral clearance, again, based at MMC.  

   Most of the time, I do the arithmetic in my head.  Without the convient tables, people might consider alternate GD&T schemes like setting the positional tolerance to zero (usually but not always at MMC), using holes as datums.

                    JHG

RE: Tolerance Calcs

ctopher,

I also do the math in my head, or scratch it down with other numbers I'm working with, but this is a good tip.  The site has alot of good reference information other than GD&T.  

RE: Tolerance Calcs

It's scary to think that there are people who would use those calculators without understanding what they are doing!

Tunalover

RE: Tolerance Calcs

(OP)
I was taught to do it by hand. But, these days I hear the excuses all the time from engineers and designers that they either don't have time (too busy) or why do it if it is available online.
Sometimes when I get very frustrated with coworkers, I catch myself doing the same. Or sometimes if I'm rushed, I may use the online site for check.

Chris
Sr. Mechanical Designer, CAD
SolidWorks 05 SP2.0 / PDMWorks 05
ctopher's home site

FAQ559-1100
FAQ559-716

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