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Help - How to Search for Point Radially or using Circular Moves?

CarbideEVO
Is there a simple way I can seek a hit target while doing a circular move, IE, looking for a clocking feature that is rotated about an axis randomly.

Ive encountered many occassions where this would be helpful - Usually it's a machined channel or grove where there is only clearance to move radially, where I cannot use Check Distance / Prehit / Retract.

Please advise, thank you!

  • Is there a simple way to find something on a part that exists randomly? No not really.

    What is the geometry you're trying to find? With a little more context & we might be able to come up with something.
  • something like a keyway in the ID but its orientation is not critical to the rest of the part and they are random? I've had that to deal with
  • Please see attached MS Paint drawing. Clocking key is inside narrow groove feature/channel, let's say 0.040" width" and can be anywhere, radially, relative to the rest of the datum structure.

    My question is:

    Is there a way to make PC DMIS seek a feature following a defined radius, something like "On Error" "Create Read Point" and then rough clock to that?
    Attached Files
  • I see what you're trying to do, but I do not know if can be done. You could try measuring a circle with arc move and set an onerror for when it runs into the key, having it set a read point, put the x,y,z locations from the read point into variables and use them to create your measurement. Just spit balling here, I have not tested this.
  • I see what you're trying to do, but I do not know if can be done. You could try measuring a circle with arc move and set an on-error for when it runs into the key, having it set a read point, put the x,y,z locations from the read point into variables and use them to create your measurement. Just spit balling here, I have not tested this.

    I've used a similar method - but with scanning rather than on-error. Define a rotary scan on the main surface at the radius you want to search, execution controls=normal / relearn, nominals method=master, boundary type=plane, number of crossings=1. Edit the end point (point 2) Z value to be just below your surface (say 0.5mm) and edit the PLANE vector to 0,0,1. The probe will scan in a radial path until it drops into the feature you are searching for (so long as the tip is smaller than the feature). Once the tip centre crosses the boundary plane - in this case 0.5mm deep - the scan will stop. You can now take a readpoint, origin on it and perform whatever other measurements you need to refine your search and measure your feature. Obviously, if your main surface is not levelled to Z, adjust point 2 and the boundary plane vector accordingly. You will probably have to scan quite slowly too since you will need a small tip - Ø0.7 max - to fit inside your feature as you say it is only around 1mm wide.
  • Are there other features on the part that you are rotating/clocking to when aligning? then, if I understand correctly, this feature is random to the clocking features??


    If there are no other clocking features then the easiest solution that I would suggest is setting the part up so the slot is located at the same position every time. (ie: 12 O'clock, 3 O'clock, 6 O'clock or 9 O'clock.

  • Hello, bring back from the dead Slight smile

    M-Cosmos (Mitutoyo) simply has a circular path point measure. You tell it start angle, radius, and CW/CCW, and it will start at that point and circular move at measure speed for the prehit distance until it measures a point (or errors). Could this be done with a circular move and on error (when it hits the surface), use read point to get an approximate result?

  • in reply to Vernon Zimmerman

    I think the issue would be that MOVE/CIRCLULAR has to be part of a feature - there are no parameters to control it.

    I would think a better option might be a vector point in a loop, with 'on miss part' incrementing the loop on.  When a hit occurs, this could be clocked to and then exit the loop.

  • in reply to NinjaBadger

    Maybe just make a loop to move to X,Y point and do some trig calculations each loop to move the equivalent of so many degrees of rotation at a given radius. I have formula saved somewhere for PR to XY coordinate calc. Could make it a subroutine with input variables for center, radius, start angle, and how many degrees per attempt.

  • in reply to Vernon Zimmerman

      You should file/request this at the Hexagon Idea Center.

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