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Tolerance Calculation in Mathcad

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Re: Tolerance Calculation in Mathcad

if you could please help me with this subtraction logic, i'll be really thankful.

As rest everything is perfect, only this subtraction part is left

Re: Tolerance Calculation in Mathcad

You are perfectly right. It is the same error I was moaning about concerning the routines by Norm and Andy which I now made myself. So I was also wrong when I stated above that their suggestions will work for Additions and Subtractions only. They will not work for Subtractions either.

So it would be necessary to write your own subtraction function.

Unfortunately "explicit" will not work as you'd like it to do anymore in this case.

ToleranceAdd2.png

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Re: Tolerance Calculation in Mathcad

Here is a sheet with an added unary minus which is a bit more explicit-friendly.

The drawback is the way you have to write your subtraction (either A + - D, or A + (-D)).

ToleranceAdd3.png

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Re: Tolerance Calculation in Mathcad

Hi Werner,

Thank you very much for the help...this will solve problems for many.

Re: Tolerance Calculation in Mathcad

Thank you, for your clarifications Werner. This worksheet was from the old collab (I believe from Stewart Bruff if I remember correctly) and I've used it on simple mechanical assemblies, but now I think i'll recheck them for accuracy.

Maybe for mechanical assemblies worse case or root sum of squares approach is best (reference attached). But alas only for symetrical tolerances.

Re: Tolerance Calculation in Mathcad

As Shashank Sharma pointed out in a later post, not even subtraction is correct with the simple approach.

So after all calculations with tolerances aren't trivial at all.

Re: Tolerance Calculation in Mathcad

hi Werner,

Just a small Help can we add a plus minus symbol as well as shown below?

tol_rep.JPG

Re: Tolerance Calculation in Mathcad

For the definition of the variable this would be no problem. Simply define a function with the name +- with two arguments (nominal value and vector) which creates that 2x1 data structure.

But for the display of the calculations or in explicit thats another story.

Here is a (in my opinion unpractical) solution which would allow only for symbolical evaluation and has its drawback with the sum of more than two summands.

05.12.png

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