Base Alignment / Space Point Question

[[Lu...]]

Hello,

We have an arc segment type of part that distorts after the machining operation (the radius becomes smaller). So, the model is a bit different than the physical parts.

The print essentially calls for arc length. I've programmed this successfully using some construction features and math functions; however, when I first tried to program it, I tried doing profile points (space points), and that didn't work. I would like to better understand why the space points didn't work.

 

Here is the strategy that I used to create the space points:

Leveling: Measured the top of the part for the base plane (rotation about the X axis, rotation about the Y axis, and Z translation)

Translation: Measure the radius of the part (obtain the center point of the part) for XY translation

Rotation: measured a line on the right side of the part. Then, I intersected this measured line with the radius of the part. Then, I constructed a line from the center of the part to that intersection point. I used this constructed line for rotation.

This is the same strategy that I used with my arc length math functions...

So why do my space points read far out of tolerance when my arc length measurement great? The form of the part form (circularity) is within tenths. Could the "space point" method possibly be fitting a nominal size radius to the part when it finds that XY center point?

[[Ma...]]

I often use plane point, because they are fixed in vector, but reports true XYZ values.

Now i don't know what space point does, but i had either space point or another type and when i was manually probing this point it was reporting only in vector correctly, but i needed Z value ( was +Y ), which was reported as nominal.

[[Ri...]]

Space Points are vector comped back to nominal, so IMO they aren't very useful unless your points are fixed to a normal direction. In most cases, Plane Point is the more appropriate choice for single point measurements, especially for Profiles. The only other one that is useful is Mid Point, but it's very limited in uses (primarily nesting into a thread, spline/gear).