Base alignment match help

[[Pe...]]

Hello,

I have an excessively long part (55 inches) that is going to have to use a base alignment match to measure the whole thing.  The part itself sits on a fixture so it was my thought that I could use the fixture itself to do the alignment match.  My plan is to have 4 points (that I engrave circles around to give a target for the operators to hit) and two circles (two reamed holes) to establish the alignment match.  Which sounds like it could make a perfectly stable alignment.

But when setting up the match, you cant tell it that the points should define the Z level and circles would define XY and you cant define a rotation in space or a planar alignment (I am guessing that it uses some sort of best fit of all features selected).  So how do I know that the manual probing of the circles aren't driving the Z and likewise the points aren't dragging XY around?

In simulation, it gives a high standard deviation for the match.  I can only assume that is because of the above issue, I can't click the manual points exactly where the nominal positions of points and circles are.  So how bad of a deviation would be acceptable?  I have set to execute as an automatic measurement after so it will run the same alignment in cnc mode to help with that.  But is there a way to loop that cnc run for accuracy or is that not necessary?

 

[[Da...]]

Use the 4 points as a plane (Rotation in space), create a 2D line on the wall of the cut-out (for Planar Rotation) and then choose one of the cylinders to control X and Y.

[[Pe...]]

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Base alignment match does not allow you to define rotations in space or planer rotations.  All you can do is select from a list of features:

[[Da...]]

How to Leapfrog alignments- alignment match.pdf

This is what I have that is similar to what you are trying to do. Not exactly what you want but maybe it can help.