Need help with IJK vectors & compensating for actual v.s. nominal surface

[[Ry...]]

Good day all,

I am struggling to obtain consistency on this particular job. We are trying to understand the tooth thickness of a bevel gear at a certain height off of the B datum (Z value) & diameter. As you can see in the picture below, the tooth of the gear is larger in real life than the nominal CAD. Since the tooth of the gear is larger, the point that my CMM takes is at a height, .002 above my target. I am thinking this is due to my approach angle at my targeted XYZ coordinate. I've sectioned the CAD model using the 'creating features' utility at the specified diameter & intersected the curve that I created with a theoretical plane at the wanted height. I then used the actual X & Y values that the intersection gave me as a formula for the nominal X and Y of the point. When I do this, I get closer to my desired Z height, but it is still not perfect. There are 47 teeth on this gear and each tooth might be different, so I need to compensate depending on each actual tooth geometry.

 

Is there an easy way to compensate for IJK based on the actual surface angle? I know I can do the math based on the plane angles but not sure how to put it into practice. Any help would be appreciated.

[[Ma...]]

Are you using plane point or space point?

[[Ry...]]

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Hi Martin,

I am using a space point. I was able to figure out my issue. I originally had shortened my curve start and end point because we were trying to evaluate a different Z height & I didn't want my probe to hit the root or tip of the tooth. We adjusted the wanted height to .222 & it seems like the scanned curve was not passing over the newly defined area we had wanted to evaluate the tooth thickness at. Using the X & Y of the curve in a single space point as a formula is achieving the desired Z height within millionths now.

[[Ma...]]

I am using plane points to obtain XYZ from manual input - with space points i didn't get real values ( i was touching plane from X/Y sides to obtain Z value - it didn't work on space point )

But I'm glad to hear you solved it - you'll remember this for a long time :-)

[[Ke...]]

Ryan, from what I have seen in this post, if this is the sort of job you work on often (or really gears in general often), you may be interested in GearPro, which handles these sorts of measurements very well and, in my opinion, easily