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Overriding Hole Sizes in Reports

gcunniff
Our engineering staff prefers that I use gage pins to measure hole sizes instead of the result calculated by the CMM measurement. This is not a problem for a diameter size callout - I simply use a Keyed In Dimension and type in the result measured with a gage pin at that point in the report. The problem is when I have to report the True Position for the hole because then the measured hole diameter for the keyed in dimension doesn't match the measured hole diameter in the true position dimension - which uses the diameter calculated by the machine measurement - not the pin.

Is there any way to override the measured hole diameter in the True Position calculation so that it will use the number that I've inputted through a Keyed in Dimension?

This is how it would look in the report -



MEASUREMENT POINTS - MP06
==========================
DIM MP06= KEYED IN DIMENSION
AX NOMINAL MEAS +TOL -TOL DEV OUTTOL
D 5.500 5.530 0.100 0.100 0.030 0.000 -----#---


MEASUREMENT POINTS - MP07
==========================
DIM MP07= TRUE POSITION OF CIRCLE MP_6 UNITS=MM
AX NOMINAL MEAS +TOL -TOL BONUS DEV DEVANG OUTTOL
X 2940.800 2940.908 0.108
Z 1290.570 1290.465 -0.105
DF 5.500 5.528 0.100 0.100 0.028 0.000 -----#---
TP RFS 0.300 0.000 0.302 0.000 0.002 -------->
  • He could also report the diameter as he is currently doing, then use the variables from the X and Y location to caluculate the TP and report that through the Generic Feature.

    +1 !!!!!
  • I would recommend taking some time and some ring gages and developing some techniques to be able to measure diameters reliably.

    Use large prime numbers of points, large pre-hit & retract, sample hits, scans, and of course Max Inscribed.

    Once you can get repeatablility within the CMM's capability, and you can prove it, then start working on gaining the trust of your engineering staff.

    A key component is to be able to demonstrate that you can measure diameters for which there are no gage pins. This will go a long way to showing them the capabilities of the CMM. Getting them to believe the numbers involves the ring gages.

    Good luck!
  • I would recommend taking some time and some ring gages and developing some techniques to be able to measure diameters reliably.

    Use large prime numbers of points, large pre-hit & retract, sample hits, scans, and of course Max Inscribed.

    Once you can get repeatablility within the CMM's capability, and you can prove it, then start working on gaining the trust of your engineering staff.

    A key component is to be able to demonstrate that you can measure diameters for which there are no gage pins. This will go a long way to showing them the capabilities of the CMM. Getting them to believe the numbers involves the ring gages.

    Good luck!

    Part of the problem is that I'm using a Faro arm - so it's hard to get consistent measurements like you would with a DCC machine that's driving along a vector. The generic feature with the variable substitution in the MEAS field works just fine.

    Thanks guys - if this even possible in the first place, I knew this forum was the only place I would find out about it!
  • Part of the problem is that I'm using a Faro arm - so it's hard to get consistent measurements like you would with a DCC machine that's driving along a vector. The generic feature with the variable substitution in the MEAS field works just fine.

    Thanks guys - if this even possible in the first place, I knew this forum was the only place I would find out about it!

    Ah, in other words, they want you to do a job with the wrong tool. Figures.
  • If the circle name is CIR1, you input values cir1.tx, cir1.ty,cir1.tz in nominal values, and cir1.x,cir1.y,cir1.z in measured values. For diameter, you can also do it with an input comment, where operator type the pin diam value, and you input COM1.INPUT in generic circle diam.

    I'll try this, too...
  • Ah, in other words, they want you to do a job with the wrong tool. Figures.


    Yeah, "limitations" is an unrecognized concept around here...
  • Part of the problem is that I'm using a Faro arm - so it's hard to get consistent measurements like you would with a DCC machine that's driving along a vector. The generic feature with the variable substitution in the MEAS field works just fine.

    Thanks guys - if this even possible in the first place, I knew this forum was the only place I would find out about it!

    OK, I moved this to the Portable section.

    I still recommend that you should measure some diameters on a ring gage and seek techniques to improve accuracy with a Portable arm.
  • OK, I moved this to the Portable section.

    I still recommend that you should measure some diameters on a ring gage and seek techniques to improve accuracy with a Portable arm.

    If I get a chance, I will snap a couple photos of parts I am working with - some are cast aluminum with a parting line (and flash) through the middle of the holes and others are 6mm thick parts stamped for cold rolled steel. Accuracy of a diameter on a ring gage is a whole different story than real world application - pin gages have always caused me less of a headache due to the fact that measured results with a pin are highly repeatable - either the pin goes through the hole or it doesn't. I've had good luck with the diameters on thin stamped parts (1.0mm or less) with our DCC machine. The Faro arm with this other crap? Not so much...
  • If I get a chance, I will snap a couple photos of parts I am working with - some are cast aluminum with a parting line (and flash) through the middle of the holes and others are 6mm thick parts stamped for cold rolled steel. Accuracy of a diameter on a ring gage is a whole different story than real world application - pin gages have always caused me less of a headache due to the fact that measured results with a pin are highly repeatable - either the pin goes through the hole or it doesn't. I've had good luck with the diameters on thin stamped parts (1.0mm or less) with our DCC machine. The Faro arm with this other crap? Not so much...

    It's really difficult for a portable CMM operator to lay the contact point of the ball on the actual ID in sheet metal applications. Frequently, we are too high/low, and the diametric output suffers accordingly. PCDMIS Portable's AutoTrigger Point & Plane functions can help us more precisely position our hits. It's easy to use, too. Just build an AutoFeature Circle as you normally would, and make sure your Depth is 0.5" (half the thickness of the sheetmetal), your # of hits is appropriate, Sample hits is set to 3.

    Then, during Execution, activate (or appropriate deactivate) Plane Autotrigger. You will be prompted to shoot your sample hits (use the surface around the ID), and that sets the temporary 0-plane. Boom, AutoPlaneTrigger activates, and the laptop starts emitting a tone as the probe gets closer to the depth you've set in the Feature. Hits will automatically be taken as the center of the probe crosses this plane. Be warned that the first time you try this, you'll inadvertently take all your hits in one location!! Delete them and stroke the probe in and out of the ID as you walk the probe around the circumference. Listen for the AutoTrigger tone to peak as you cross it, and then fade in tone.

    The upshot is that you'll be guaranteed to have the hits positioned at the identical height, giving you truer results for your circle.
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