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Thickness of a wedge shaped part

Parker
Hi All,
I need to measure the thickness of a wedge/pie shaped part very accurately. Both sides of the wedge are flat, but obviously not parallel by design. (About 0.5 degree angle). I can probe both sides of this part if I stand the wedge up. With my current method, I believe I am getting some cosine error in the measurements, but am not sure. My current method is to establish a coordinate system using one side as the primary datum, call it the "straight" side. I level to X-, set X origin. I then take points at the same Y and Z coordinates on both sides. As you move along Y, the part thickness changes. Using the CAD I pull the vector for the "angled" side and set the points to the same Y and Z as the "straight" side. I also am using the smallest diameter probe I have. Does this approach sound correct? Customer is questioning my results so I want to make sure I am doing this the correct way.

Thanks!

  • By definition, there's no way to measure thickness of a wedge. You can measure at the wide end or the narrow end. You could do opposed points at pre-defined locations. Print could define it as profile.
  • I agree with kingsld1. I would look at the opposing points on the angle side as individual profile points. Or try to talk your customer in to this perhaps.
  • I would not use the same Y&Z on both sides. I would copy the points from one side, then paste with pattern MIRROR in the X. Yes, the new points will be in the same place and at the same XYZ values. HOWEVER, you simply hide all the cad data EXCEPT the side you want the points on, then F9 each one and click "FIND" (and ONLY find) and it will project them onto that surface at the shortest distance from their current location. This will keep them at the same 'thickness' place of the wedge and not slightly skewed (as I think you are finding).

    All that being said, NO, you can not check the thickness of a wedge. It has no 'thickness', it has a constantly changing nominal value. 'Thickness' has a single nominal value.
  • I should clarify, I meant thickness at each of those individual locations. Basically shortest distance between opposing points at a set Y and Z location. I'm torn between methods and don't know which is right. Method 1: The fixed Y&Z location for both straight and angled... and the method Matthew just described. The print does call one side "straight" and calls it a Datum. There also is a profile call out to that datum.
  • in reply to Parker
    Profile callout defines the thickness at that point. I'd just use that.

    Is the width/thickness actually called out?

    As far as cosine error, if you take hits on the model, the probe is going to approach at a normal angle.

    If you wanted to, you could trig out the distance between two points on each side and use that nominal for a 3D distance.
  • in reply to Parker
    As long as you are using correct nominals for the points, Pcdmis will calculate the correct 3D distance, no need to do it by hand
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