my small tip =(

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  • my small tip =(

    hello all
    my small tip (0.5mm) always measures stuff bigger than it really is. (about .006-0.1mm) even tho i just calibrated it.
    it calibration results it get good std, but the the diameter always measures to 0.480 mm.
    anyone has any tips & tricks for my small tip?

  • #2
    Good day,

    please check first if the calibration and measurement are carried out with the exact same touch speed.

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    • #3
      I would not worry about the size reading 0.480 it is normal for the ball to read smaller as an example our 0.7 styli read around 0.638 but give very repeatable accurate results.

      If you are getting up to 0.1 errors, I would advise checking the probe is not shanking out. The 0.5 ball does not have much room for error in the physical alignment of the part.

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      • #4
        might i sugguest checking the size of the calibration sphere and your parameters set on the cmm correlate with each other

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        • #5
          Different ruby sizes & styli lengths than advertised its a normal thing. Machine ought to calibrate & calculate how much to compensate. Like others have said check probing parameters, sphere size & touch speeds. Cal touch speeds have to be the same as with program touch speeds to start. Moreover, Hexagon level 2 training manual's got touch speeds for different probe sizes & probe heads under Autocalibration section. I use very low touch speed in calibration & programming to prevent styli bending. I also calibrate with more points than minimum on the sphere.

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          • #6
            You have any ring gages that you can measure ? You see the same thing on a width for example ? Measuring a hole with 1 tip and comparing it to another ? Please expand on your question / information.

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            • #7

              calibration parameters are almost the same.
              for my 0.5mm tip the only difference from the other tips is that i start measuring 10 degrees above the equator not to get shank.
              measuremenet speed is the same

              Schlag
              yeah i have program that checks probes against a ring and a sphere, this is where i noticed the small tip always measures the diameter of the ring/sphere to be 0.006 - 0.012mm smaller than the other tips measures it too

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              • Mike Ruff
                Mike Ruff commented
                Editing a comment
                Check the circularity of the ring gage diameter as well

            • #8
              have you checked the ruby size with mics? or comparator or anything to see if its correct? Sometimes deleting the probe file and making a new one clears things up when I've had stuff like that happen.

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              • mbatten
                mbatten commented
                Editing a comment
                Be careful with this, you could damage the ruby or break it off the shank if you're not gentle.

              • markoor99
                markoor99 commented
                Editing a comment
                isn't one of the qualifications for being a good cmm programmer delicacy?

            • #9
              Is the tip defective? Have you checked the ruby under magnification to see if there is a crack?

              What's your touchspeed at ?

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              • #10
                have you checked it to a standard ring gage?
                do that first, get your results, and edit the tip diameter size. rinse repeat until the ring gage measures correctly.
                Che Guevara is a communist scumbag.

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                • #11
                  Maybe the 10º off from equator is messing up the probe compensation(shouldn't). Can you calibrate 0º-90º and then retest your gage evaluation? it would show a change right away if it were the issue.

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                  • bfire85
                    bfire85 commented
                    Editing a comment
                    Yeah the probe won't shank at the equator. So I am not sure about the 10° thing either.

                  • KatmandudaMeow
                    KatmandudaMeow commented
                    Editing a comment
                    I would check how square the head is to the machine axes (use a dial indicator and lock 2 axis check in linearly and also see how straight the whole build setup is to a straight edge. If you're calibrating off 10° then it seems something isn't straight IMO

                • #12
                  What probe system do you have? Any time I use a probe under 1mm, I significantly reduce probe touchspeed.
                  Depending on probe system that speed can be 1mm/sec for tp200, or 4mm/sec for our HP-S-X1H scanning head.

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                  • #13
                    Yep, I would slow touch speed down at calibration and continue to do this until the ring gage measures correctly.

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                    • #14
                      .5 mm touch speed is what I run for a .5X20 mm probe tip on a standard force module with a TTP. Ring gauge accuracy was usually .0001 to .0000.

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