Tolerancing a 'V' block

[Nathan448]

Hello is this correct?
I would like the H7 holes to hold dowel pins which are used to align the V block, which must hold a shaft perpendicular to them.
I am concerned I have not placed a datum onto anything 'real' although the machinist would make a shaft at the reference diameter to check the tolerance.

We are in Australia and use AS1100 however, AS standards are quite similar though to ASME standards, however I couldn't see a problem with someone with ISO1101 knowledge giving answer.

All dimensions are in mm

Thanks,

 

[mkcski]

Hathan448

Use of the datum A as you have shown is not "appropriate". It may add more confusion and regarding selection of material condition modifiers for partial features of size

I suggest "flipping" the features and locate the face of the V's from the holes and other "added" features. I would apply a "loose" position for the two holes relative the bottom face (primary, 3 motions controlled) one side (secondary, two motions) and a second side (tertiary, 1 motion). You can refine the perpendicularity inherent in position to make the holes "more" perpendicularity to the bottom face. I would then apply profile of a surface to the 90-deg V-faces, with the bottom face (primary - 3 motions) and make the pattern of two dowel holes the secondary datum (3 motions). Hope this helps.

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