Question on defining run-out between multiple holes of identical diameter in pairs

Hi all,

I have jut completed the Level 1 course on Geometric tolerancing to BS8888 and ISO standards but I am finding it quite difficult to apply it to my own drawings. Any help on tis problem would be appreciated.

The part I need to tolerance (see attached) has 4 diam6mm holes and 8 diam5 mm holes. I would like to:
1) have the four diam6mm holes circular and concentric to each other, enough to fit a long shaft through them with an H7/h6 location fit.
2) have the other height holes toleranced by group of two so that:
- I can fit a small shaft through each pair with an H7/h6 location fit.
- the axis defined by the pair of holes is parallel to the axis defined by the 4 diam6mm holes
- each pair of holes is toleranced independently to the other, I do not want to over constraint he part by making all holes aligned.


I have tried to use a run-out tolerance to control the circularity and concentricity of the holes at the same time but I don't know how to make it clear that it should apply to each pair without repeating it four times. Also, which one is the correct way to define datum B: B1 or B2? and would B1 apply to all four holes because of the "4x"?

Many thanks for your help,

Alizee

This is a very basic question and course should have covered the methods of identifying many features as one..

Does the course author or provider have a help email or forum?

Obviously, here at Engineers Edge we have a support forum for our classes as well as provide you with a contact (me).

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