Wall thickness at an angle

[[No...]]

I have a problem with the measurement of wall thickness. I know the solution, but I'd like to understand the problem.

I often have to measure the wall thickness of tube-shaped parts at different angles. Say I have a tube with inner diameter 50 mm and outer diameter 52 mm. Wall thickness has to be measured at 8 points around the tube (every 45 degrees).

The most intuitive approach for me in Calypso would be to measure two circles with 8 touch points at the same angles, recall all the points to single points (recall feature points --> add range limits --> point number --> recalculate nominal geometry) and then calculate the distance of the corresponding pairs with simple distance (3D) or 3D polar distance.
But that doesn't work. It only works for the points at 0, 90, 180 and 360 degrees, but not for those at 45, 135 etc.

In the example above I should get a nominal distance of 1 mm for each pair of points. But at 45 degrees I get a nominal and actual of 3.566 (in simulation). Can anyone explain this? This is what Calypso shows in the CAD window (light blue points):




By the way, the working solution is to use space points with a rotational pattern instead of circles. But I'd really like to understand what is happening here.

[[Ma...]]

Correct your vectors on points.

[[No...]]

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I have (not in the pictures). Makes no difference as far as I've seen.
I wonder why it isn't able to calculate the correct vector itself when I recall the point.
I've checked "recalculate nominal geometry".

[[Da...]]

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Norbert would go with another intuitive approach - with points with rotational pattern:

[[To...]]

If you used an inner and outer point using a rotational pattern, the point evaluation would need to be a plane point or space point and 3d distance should work. So, maybe the evaluation of the recalled points is set to touch point and needs to be changed to space point.

Geez. I see Dane is on a similar track...lol

[[Ri...]]

Rotational pattern is the easier approach.

I believe I've had this issue before, and it's due to the nominals not being correct (mainly vector), so it gets skewed like crazy.

[[No...]]

I had mentioned space points in my very last sentence 😃
But thanks anyway.

So the culprit is the touch point setting? Why? And why is this even necessary?
Doesn't it just need the point coordinates?
And shouldn't the actual points (light blue) at least be at the correct position, regardless of the vector?
That's what I just don't understand. I mean, it doesn't need to do any radius correction or something.

[[Da...]]

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Uff, sorry I was sloppy when reading.
And IDK the answer to OP.

[[Ri...]]

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Yes, it is still doing vector comp. That's the problem.

[[An...]]

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The calculation of the correct vector requires the appropriate surface data.
CALYPSO is for sure not able to calculate these data by the X;Y;Z coordinates
of the point.
It needs a special probing.

[[Ne...]]

Do you have curve? if so you can make two curves instead of circles and use the curve distance characteristic and it should work.

Also out of curiosity, did you try creating an alignment that was 45 degrees to base alignment and using it in the recall circle points
on the 45 deg's?

Neil

[[Ja...]]

You could measure point to point at zero degrees, create an alignment characteristic, in that alignment click on special, and rotate 45 degrees. Copy/paste your first two points. Go into to each new point, tick "keep position", and change to the new alignment. that will move your point 45 degrees and the vector will be correct. Uncheck "keep position" and change back to base alignment. Your points will stay there and they will be relative to the base alignment again. Copy/paste the new points and keep repeating until you have them all. Their should be an easier way but that always works for me.

[[No...]]

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I was hoping that a recalled point would carry over that kind of data.
Looks like I'm already GOM-spoiled 😃

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No, I didn't. Just because it's less effort to create space points with a pattern, I guess.
But I'll keep that alignment method in mind for a future task that needs it, thanks!