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-Z Point vector angles aren't square to CMM


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Hello all,

I have a program that checks Perpendicularity and upon manual verification, I find it to be much less than what the CMM is telling me. After some investigation, I have been noticing the vectors on my -Z points have been at an angle. 

What could be causing this, and could this be playing a significant role in some of my bad results on Perpendicularity, Runout, etc.? 

Below are images of a sample plane that I had probed on the surface plate of the CMM and the feature data.

 For context I am using a Contura G2 (Vast XT) Calypso 2020. Calibration occurred in April. 

image.png.2292363cd5d81c08fab0e61b057bfabb.png

image.png.1ba99e6d562b55f15525c75ad0e855f8.png

image.png.6fdb5444a47b9d34d381631585fcd065.png

 

Thanks in advance, 

Christian

image.png

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The angle of the point vectors do not affect calculations like runout or rectangularity, only the actual point coordinates are relevant for this.

BUT if you get vectors that skewed when touching the granite, there might indeed be something wrong with your probe head. I suppose you took these points in the machine coordinate system?

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 No recent major Collisions and this is happening with multiple stylus systems. (1mm cone stylus with extension and 8mm with carbon shaft). Surfaces are always as clean as we can get them. 

 

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 Yes, I was using the machines coordinate system and probing the granite of the CMM. I will reach out to Zeiss Support to try to get this resolved if the head is suspected to be the issue, which is what I was afraid of.

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First, The granite can have a porous surface, chips, and scratches. Small probes can fall into the pores. Its always best to check the part, and not a mated surface. When possible of course. 

Secondly, the surface you checked (the granite) is larger than the part resting on it. So depending on how you are asking for the perpendicularity (Is the Perp From the plane or are you measuring the perp OF the plane) it may read as a higher number than when you check it manually. You can make the plane the same size as the part by changing the nominals to match your part size.  I hope that makes sense. 

PSH and WNTGFABS !🍺

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I am wondering - are those green arrows from manual or CNC touch? There can be difference if it's show before / after base alignment.

Am I seeing one green arrow with correct vector?

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