True Position with different axes.

[[Da...]]

I have a roughly cubical part, with threaded holes on the 4 sides. They are called out with true position to .2 mm with datums A|B|C a group.

I am getting results from calypso that do not seem to mesh with reality. The report says that some are out as much as 10 mm.

Doing true position for each side individually yields more like .3 mm for each.

Any ideas as to what is going on?

[[La...]]

Do the coordinates in the TP characteristic (X/y, Y/Z, etc) match those of the drawing?

[[Da...]]

Please sign in to view this quote.

It is a MBD part - I don't have basics on the drawing. The angles are all correct though.

It is in Calypso 2019.

[[Ja...]]

How are you measuring the threaded holes? Filters/Outliers?

[[De...]]

If these holes are at a angle / compound angle relative to the datum reference frame, then you will need to input the basic position / angle of the hole by hitting the special button and inputting the offsets to the hole and the angle / angles of the hole relative to the datum reference frame.

[[Da...]]

I am measuring the holes with 6 linear paths, 2 mm/s, .01 mm step width.

Evaluating as Maximum Inscribed Element. Filters - Gauss, low pass, wavelength .25mm. Outliers +/- 3 sigma, only outlier, 1 iteration, wavelength 0-2.5mm

The top of the cube is datum A, and the slabs of the sides form datums B and C. The holes are perpendicular to the face they are on. That is, they are 90 degrees to datum A.

[[Ja...]]

So your nominal values for the axis would be approx. half the width of the "cube" with a tolerance zone in the two directions whose cross product lies along the axis?

[[Da...]]

Please sign in to view this quote.

I think so.

Imagine a 1-2-3 block, with holes only on the 1x2 and 1x3 faces. The 2x3 face is datum A, and the middle of the other two axes are B and C. I need true position of the side holes as a single pattern.

[[Ja...]]

Set your origin at a corner of the cube (Level to A, Rotate to B, Translate X, Y, and Z to A, B, and C as appropriate). Rotate probe, measure threaded holes using linear scans as you have done. Now you should be able to just report Position. Using CAD? Great, nominals should be good. No CAD? Geometry should be able to help you determine what your noms are.

I would suspect alignment issue if you're getting results that far out. Can you post a screenshot of your model with alignment trihedron?