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Validate my method is fine please (programmers differ in opinion)

Lord_Warfield
Good Morning Interweb,

So I have a simple alignment. Plane A, circle B, circle C. I Leveled to the plane A and origin Z to it. Translate XY to circle B. Rotate to a line made from B to C. Done.

A different programmer believes I must rotate before translating.... I totally disagree on this simple alignment. Using Legacy btw.

Without being degrading... please reply.
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  • I often rely on:

    Measure plane
    - Align: Level and origin Z
    Measure circle 1
    - Align: Recall previous: Origin XY
    Measure circle 2
    Construct line between cir1 - cir2 centroids
    - Align: Recall startup, then Level, Rotate to constructed line, Origin

    Doing this makes sure the rotation vectors that you take for the circles are normal to your component's level plane.
    Also, if your initial origin is perhaps dead-nuts centered between the two circles, you have a chance of flipping vectors as the polarity of your rotation can shift from centroid super easily, and 180 your entire routine.

    This method I have had internal issues with. never anything i have documented or researched in any way but i believe (again just a mental simulation no proof) creating multiple alignments when creating your final alignment would incorporate deviation from the previously measured features. thus changing the location of the part with each alignment.

    vs measuring the entire alignment features from one single alignment whether it be a manual alignment or the CMM startup alignment.

    Just an opinion.

    i would also like to state that in this example of plane circle circle i dont think it would have too much of an impact. however on a plane line point alignment or anything with more chance for deviation during measurement would have a greater impact on the alignment.
  • in reply to cheesiechanman
    Respectfully, the ultimate goal of alignments is to isolate any variation, as-contributed by the part not being squared to the machine's system/components.
    If you level and origin Z first, you prevent introducing bias from vectors being incorrect whilst probing the following alignment features.

    Creating multiple alignments is entirely irrelevant.
    --As long as your final alignment recalls startup, then Levels, Rotates, & Translates all six degrees of freedom per PCDMIS guidance... whatever you programmed before that recall/startup command is the same as not existing in the eyes of the demon.

    Doing your initial align this way enables you to confidently mitigate almost all cosine error from those hits.
Reply
  • in reply to cheesiechanman
    Respectfully, the ultimate goal of alignments is to isolate any variation, as-contributed by the part not being squared to the machine's system/components.
    If you level and origin Z first, you prevent introducing bias from vectors being incorrect whilst probing the following alignment features.

    Creating multiple alignments is entirely irrelevant.
    --As long as your final alignment recalls startup, then Levels, Rotates, & Translates all six degrees of freedom per PCDMIS guidance... whatever you programmed before that recall/startup command is the same as not existing in the eyes of the demon.

    Doing your initial align this way enables you to confidently mitigate almost all cosine error from those hits.
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