True position

[Bob Pierce]

When dimensioning TP of a 2D hole to datums ABC, the hole being normal to Z, is the Z location being used in the calculation?

[Jan d.]

Yes, typically your datum A is a plane perpendicular to the cylinder. If the hole is far away from datum A and it is slightly angled, this is all taken into account when PC-DMIS calculates the TP.

I have a lot of calls where my datum plane is about 4 to 6" above my actual cylinder. I can see the numbers get real bad quickly, when the hole is not drilled straight. I am quite convince that in V4.2, PC-DMIS evaluates this correctly (as you may know, I never used anything before V4.0).

Jan.

[Matthew D. Hoedeman]

When dimensioning TP of a 2D hole to datums ABC, the hole being normal to Z, is the Z location being used in the calculation?

It is IF:

1) You are using surface samples (as you should)
-AND-
2) You include it in the TP dimension

-OR-

You can keep reporting it as you are and mark the DEVIATION PERPTO CENTERLINE box for the TP, this will give you a simulated stab-pin check result (best method for sheet metal) and eliminates all the surface deviation from the TP calculation

[Bob Pierce]

It sounds like and it had been mentioned in a prior post, although I did not quite understand, that for my application I will use the perp to centerline to eliminate the surface deviation. Calculations on XY only.
Thanks

[dandrewsca]

If you are in doubt to the calculation, try this....

construct a generic point at the holes nominal location - all three axis
move your origin to the generic point
rotate to the surface (make the surface a 1 vector) and
output your actual hole location

I always output xyz location to the main datum scheme and then output the tp as per above to give the tool maker the ability to adjust the tool if required

Hope this helps
Dan