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Tolerance Calculation in Mathcad

Forum|Forum|12 years ago
December 4, 2013
3 replies
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Hi all,

After doing so many complex design and engineering calculations, i am stuck with this simple plus minus calculation.

I have to do this addition and subtraction of dimenssions with tolerances, as shown in the attached image.

Request you to please help.

As i want similar representation of Tolerances in mathcad sheets.

Thanks,

Shashank

Statistics_Analysis

Best answer by Werner_E

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)).

R

Raiko

17-Peridot

Hello Shashank,

hope this small routine will do. Add cells to the nested array Y as much as you need

Cheers

Raiko

P.S.

This is a MC 15 sheet

1_Compute-Tolerance-xmcd.zip

N

nas0k

1-Visitor

Another example to add along with Raiko's for your Mathcad toolbox. Also, a MC15 file but will convert to Prime.

I hope this helps.

1_Tolerance-Worksheet-xmcd.zip

W

Werner_E

25-Diamond I

Nice idea. Do you know why your inverse +/+ does not work as modificator placed in the unit field at the end of an evaluation? It should in my opinion but it keeps moaning about the argument is not a vector?

Working with tolerances is easy if you stay with addition and subtraction only, but going further your approach may fail because you assume you get the minimum/maximum value of any calculation by applying the minimum/maximum value of every variable involved. Unfortunately thats not true as the following simple example shows.

04.12.png

Furthermore it is not for sure that every calculation will end up in a symmetrical tolerance interval.

A

AndyWesterman

12-Amethyst

Hi,

I tried various ideas for this approach.

Most of the applications, however, became too complex to make it useable for what I needed.

attached is a simple sheet with a few functions - hopefully they will give you some information about mathcads capabilities

If you make any useful modifications to these functions, I would be grateful if you could publish them here.

Regards

Andy

1_tolerance-xmcd.zip

W

Werner_E

25-Diamond I

Hmm, all these approaches only work OK if you just use addition and subtraction in your calculation. It may fail if using multiplication and/or divison or functions, absolute value, etc.

A more general (but also more cumbersome) appraoch can be found here: http://communities.ptc.com/message/199660#199660

Its in Prime2 format.

S

ssharma-2

Author

1-Visitor

Thank you all for your kind responses,

But what i need is actual tolerance representation and the logic behind upper and lower tolerance calculation while adding or subtracting parent dimenssion values.

Thanks