A-c datum alignment

Opinion needed:

Was wondering if it was possible for one of these holes (dat-c-) to give good t.p readings. Since the parts is symmetrical all 3 holes should be used with dat-a- for an alignment (a-c in feature control frame). So it would be possible for a different selected hole to be dat-c- and give out of tolerance true position readings. Correct?

Attached Files

PART (2).pdf

Parents

UKCMM over 9 years ago

First the part is not symmetrical about the centre datum a small amount of rounding has been used in the order of 0.0003"-0.0004" this will have an effect on the final results.

Depending on which hole you start with and set the ' C ' datum then the results can be out of tolerance.

If you create a set of generic holes pitched perfect to the drawing dimensions then off set a centre point 0.0015" along the Y axis the position diameter will come out at 0.003" for all
holes.

If you now create a line between the offset centre point and one of the lower hole and rotate align to that then the position results now vary between 0.0021" 0.0045".

Think you need to talk to your customer about using a best fit to the holes
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UKCMM over 9 years ago

First the part is not symmetrical about the centre datum a small amount of rounding has been used in the order of 0.0003"-0.0004" this will have an effect on the final results.

Depending on which hole you start with and set the ' C ' datum then the results can be out of tolerance.

If you create a set of generic holes pitched perfect to the drawing dimensions then off set a centre point 0.0015" along the Y axis the position diameter will come out at 0.003" for all
holes.

If you now create a line between the offset centre point and one of the lower hole and rotate align to that then the position results now vary between 0.0021" 0.0045".

Think you need to talk to your customer about using a best fit to the holes
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel

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