Position of two parallel holes with CZ and no datum (see ISO5458)

[[Sv...]]

I have 2 nominal parallel holes with a TED, CZ, an no datum.

According to ISO5458 I have to associate two parallel cylinders (around the points of axis) with the constrain of the TED where the size of the zones is minimal.

If I got it right, I can´t use the Calypso-parllelcylinders because this builds the cylinders around the integral surface and not around the axis and there is no constrain of the TED.

Does anybody has an idea?

[[Ma...]]

Wouldn't this be interpreted as a pattern? I can not imagine how you would calculate a value of a position when you have free space there - like TED diameter smaller than real diameter.

[[Sv...]]

Yes indeed. It“s an example out of ISO5458 the standard for position of pattern.

When the diameter doesn“t match you will have two cylindrical tol. zones of the same size. I think the minimum criteria for assoziation is the diameter of both. The problem ist that orientation and location of the zones is defined by the pattern itself. There are no outher constrains.

I also can‘t use the pattern function in calypso becaue you need an datum for that. But I do not have one.

[[Ri...]]

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Have you tried creating a Parallel Cylinder from the two individual cylinders? Features - Special Geometries - Parallel Cylinder. 

Then you would create a Position for each individual cylinder where the datum is the Parallel Cylinder?

If you have the new GD&T engine, you could do this with simultaneous evaluation.

[[Sv...]]

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Yes, I´m still checking that, if I can use this as a plan B.

The Problem here is that this parallel cylinder is made for common datums with fixed TEDs (so the TED is probably fixed here). But now the but... if I would like to follow the specification operator for my verification I have to use the derived points of the axis (midpoint of gaussian circles) for my association an not the integral points of the cylinder surface as it´s the case with datums. 

The second thing is that I have two positions then but I just have one characterisitic, so an additional calculation is necessary.