sample hits

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  • sample hits

    Hi all

    Does sample hits (using 3 points) override the vector/direction of 3D-features?
    I.e. if i take 3 sample hits for a cylinder, will the cylinder have the vector of the sample hits or from the centerline of cylinder?

    So if I wanna evaluate an angle between a plane and a cylinder with sample hits. would it dimension the angle between the plane - sample hits, or plane - center line of cylinder?

  • #2
    The sample hits (for a cylinder) set the measuring vector but the result vector will be the hits in the cylinder, sample hits are 'reference' hits, so it will use the C/L of the cylinder
    Originally posted by AndersI
    I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.


    • pcdmisstudent
      pcdmisstudent commented
      Editing a comment
      so the 3 sample hits are basically just an alignment?
      And what if theres no "real plane" and the surface is curved. Will the 3 points just act like a bf plane?

    • Matthew D. Hoedeman
      Matthew D. Hoedeman commented
      Editing a comment
      3 points can always make a plane. The purpose of the sample hits are:
      For determining the depth and initial vector of the feature.

      Circles, cylinders, SURFACE points (and probably others) can have sample hits. For the circles & cylinders, they are used as above (depth and vector) for SURFACE points they are used for the check vector of the surface point. A little overkill for SURFACE points IMO unless you are dealing with micron tolerances.

    • pcdmisstudent
      pcdmisstudent commented
      Editing a comment
      Oh okay: So if using sample hits on cylinder it "overrides" the initial nominal vector from the CAD's nominal value?
      And in other words, its not good to use for holes on curved surfaces like a hole drilled thru a spherical object?
      Or im i just noob at vectors

  • #3
    SAMPLE HITS. This is a function that was originally put in for SHEET METAL MEASUREMENTS because sheet metal (and plastics) are all but impossible to hold to correct form.

    1 sample hit:
    This will ONLY allow you to set a specific depth of measurement, it will not use anything but the THEO vectors.

    3 sample hits:
    This will allow you to both set a specific depth of measurement and a TEMPORARY vector to measure the feature at. Mostly useful for hole in thin stock part. Not really something that should be used for BLOCK type parts, as in MACHINED details.

    EDGE POINTS can have up to 5 sample hits or as few as 1, the number of sample hits changes WHAT is sampled.

    For a block-type part and measuring a cylinder, I would use ONLY 1 sample hit so you can control the depth for the 'top' ring of hits. Same deal for a hole drilled in a spherical object, you set WHERE the sample hit is going to be (by the start/end angles) so that it will hit in the 'lowest' area and thus give you a ring of hits for the circle that do not skip over the top of the part.
    Originally posted by AndersI
    I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.


    • pcdmisstudent
      pcdmisstudent commented
      Editing a comment
      Thanks matty
      i wondered because i evaluated the plane against cylinder drilled thru a big radius, and then same plane with same cylinder +3 sample hits, and the result varied 0.5mm

  • #4
    and the result was better with 3 sample hits


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