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Round (tube) parts alignment (Romer Arm)

Dear forum members, does anybody can share his/her experience of round parts alinment when using a portable arm? I tried to align tube with two rounded slots and through holes but each time I faced with inversion of two coordinates after alignment - when moving probe in x+ or z+ ditection it translated in x- or z- direction accordingly in pc dmis interface. I have no any idea what should I start from to prevent this inversion. Please help.

Attached Files
  • I'm sorry - I didn't check the photo after uploading. Please look at attached pdf - this is sketch of tube I tried to set alignment for.
  • I tried to set alignment today, and from the 3rd alignment part was found correctly (all steps listed in attached file)Slight smile. When part be aligned 2 issues to be solved:
    1) to align part with round slots oriented perpendicularly to the table surface,
    2) to change vector direction in plane settings (F9) if inversion in probe movement has been found (Z- instead of Z+, X- instead of X+)

    Attached Files
  • Try aligning using the circles directly (not creating a line between them). Remember that the DIRECTION of the line between the CIR1 & CIR2 is important, if you get this wrong you will get a flipped alignment, just as you mention.

    Primary alignment use the plane.
    Secondary alignment, select CIR1 and then CIR2 and Y-PLUS around Z-PLUS (the selection order of the circles are important).
  • I don't have a Romer, but I work exclusively with cylindrical parts. The machine has a rotary table that all of the parts are loaded on to. I do the following:
    - Measure a circle around the OD
    - Take a point on the face
    - Rotation Feature
    Now, usually there is a notch on the part. I'd take two points (one on each side, left/right) and construct a midpoint. I would construct a parallel line from the circle to the constructed point. Keep in mind the line's "K" value, which should be positive.
    The circle's "J" value should be positive. Create an alignment:
    Level Y+ to the circle who's "J" value is probably 1
    Set the circle to the X and Z origins
    Set Y origin to the face of the part
    Rotate Z+ to the line (who's "K" value is probably 1) about Y+

    The problems I would usually have with aligning round parts was in the construction of the parallel line I use to align. If I were to make the line from the midpoint to the circle, "K" would be negative, A.K.A down, thus if I try and align Z to this line, it would point downwards. To fix this I just recreate the line from the circle to the midpoint.

    This may not be what you're looking for, but I hope you (and of course anyone else) can take something from my process.