L Shape Probe Calibration

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  • L Shape Probe Calibration

    Hi all

    i Have an L shape probe that keeps losing calibration. It will go from .0001 stdev one day to .002 the next. I have a 2by20 i use as master. I tried changing start and end angles, nothing is loose on the probe either. It keeps giving me the Failed Calibration error. i changed the 1by10 tip, same. changed the TP20 also, still same. changed the extension, still same. i don't know what is happening. I use this setup a lot and i desperately need it to work.. It will calibrate okay one day and completely off the next. I cleaned everything a million times-but nothing has helped. Usually the first indication of it losing calibration is that it will give me crazy results when measuring a part. I calibrate my tips daily and like i said i use a master tip. PLEASE HELP!!
    Attached Files

  • #2
    I'm actually using a TP20_6WAY module. I deleted the probe and re-created it that's why in the picture it's a standard TP20

    Comment


    • #3
      1) Ensure that the file itself that your probe files are stored in IS NOT "read only". If it is "read only", the software can't write to OR update the file once you calibrate, so nothing would actually be happening at a software level when you tell the machine to physically calibrate. This is a windows setting.
      2) Ensure you're calibrating correctly. Master probe you should say YES sphere has moved for T1A0B0, all other tips on the Master and for all other tips on all subsequent probes, you should be saying NO sphere has NOT moved.

      With the above being said, there are also environmental factors that could cause a change in accuracy..

      FOD in the air (oil particulates, dust, chips, etc settling on the probe)
      Temp fluctuations
      Humidity fluctuations

      Is this a shop floor CMM or one in a nice clean lab with temp control?
      Last edited by DAN_M; 11-20-2020, 02:11 PM.
      Beep beep beep..

      Comment


      • #4
        Originally posted by DAN_M View Post
        1) Ensure that the file itself that your probe files are stored in IS NOT "read only". If it is "read only", the software can't write to OR update the file once you calibrate, so nothing would actually be happening at a software level when you tell the machine to physically calibrate. This is a windows setting.
        2) Ensure you're calibrating correctly. Master probe you should say YES sphere has moved for T1A0B0, all other tips on the Master and for all other tips on all subsequent probes, you should be saying NO sphere has NOT moved.

        With the above being said, there are also environmental factors that could cause a change in accuracy..

        FOD in the air (oil particulates settling on the probe)
        Temp fluctuations
        Humidity fluctuations

        Is this a shop floor CMM or one in a nice clean lab with temp control?
        1-It is Read Only. I will change this
        2-Yes i'm doing as you say

        3-this is in a clean temp controlled room and only operated by one person

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        • #5
          Originally posted by Disal View Post

          1-It is Read Only. I will change this
          2-Yes i'm doing as you say

          3-this is in a clean temp controlled room and only operated by one person
          Okay i unchecked read only-will let you know what happens

          thank you for respodning

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          • #6
            So it failed cal again-Stdev .0009-.0006 on all angles. I re-calibrated and it came out to .0003-.0002 so I let it run because i'm super behind on production.
            Any other ideas please??

            i noticed some of the hits it takes it beeps twice. i think that's one of the issues. And it's not on the same spot that it does that, it does it randomly anywhere on the sphere.. I'm lost. I changed the module, extension and tip also so it's basically all new

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            • #7
              The beeping twice it only does it on this setup not on my other tips

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              • #8
                Originally posted by Disal View Post
                So it failed cal again-Stdev .0009-.0006 on all angles. I re-calibrated and it came out to .0003-.0002 so I let it run because i'm super behind on production.
                Any other ideas please??

                i noticed some of the hits it takes it beeps twice. i think that's one of the issues. And it's not on the same spot that it does that, it does it randomly anywhere on the sphere.. I'm lost. I changed the module, extension and tip also so it's basically all new
                FIRST TIME calibrations can have 'funky' values if the build isn't perfect, BUT, if you do NOT reset probes, it will use the previous calibration values as the 'theo' values for the next calibration.

                That being said, if you are working with probe files that have, for whatever reason, been made READ ONLY, then you are never, EVER checking a part with a calibrated probe.
                sigpic
                Originally posted by AndersI
                I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

                Comment


                • #9
                  Originally posted by Matthew D. Hoedeman View Post

                  FIRST TIME calibrations can have 'funky' values if the build isn't perfect, BUT, if you do NOT reset probes, it will use the previous calibration values as the 'theo' values for the next calibration.

                  That being said, if you are working with probe files that have, for whatever reason, been made READ ONLY, then you are never, EVER checking a part with a calibrated probe.
                  I have Reset Tips checked

                  We changed the Read Only-but just to mention it-i still had full access to eevrything even though it said Read only

                  what is bothering me is that everything was calibrating okay until last week. I tried all the things i mentioned and i don't know why was it calibrating good all the time until last week. There was no crash, it just started giving us weird results so i calibrated and then it started doing this

                  Comment


                  • #10
                    Originally posted by Matthew D. Hoedeman View Post

                    FIRST TIME calibrations can have 'funky' values if the build isn't perfect, BUT, if you do NOT reset probes, it will use the previous calibration values as the 'theo' values for the next calibration.

                    That being said, if you are working with probe files that have, for whatever reason, been made READ ONLY, then you are never, EVER checking a part with a calibrated probe.


                    I'm super worried about this statement!! I never knew this. I'm going to check all my other machines now

                    Comment


                    • #11
                      0.0002"-0.0003" are normal stddev values. You may want more or less accuracy depending on your tolerances and probing system that you're using but in general if I saw that I wouldn't be worried at all unless it was my reference probe.

                      My personal settings...My MASTER (4X20) will alarm out if STDDEV>0.00010, most other probes will alarm out if STDDEV>0.00025, certain weird/heavier/longer probes I use for lower tolerance jobs will alarm out at STDDEV>0.00040

                      Good, check those other machine my friend, you need to have full permissions and full read/write (preferably admin) over any file that has anything to do with PC DMIS or you'll start having a bad time.
                      Last edited by DAN_M; 11-20-2020, 02:19 PM.
                      Beep beep beep..

                      Comment


                      • #12
                        Originally posted by DAN_M View Post
                        0.0002"-0.0003" are normal stddev values. You may want more or less accuracy depending on your tolerances and probing system that you're using but in general if I saw that I wouldn't be worried at all unless it was my reference probe.

                        Good, check those other machine my friend, you need to have full permissions and full read/write (preferably admin) over any file that has anything to do with PC DMIS or you'll start having a bad time.
                        I agree on up to .0003", but this tip changes daily from that to .002 sometimes without me doing anything on it

                        So all machines have "read only" but i have full permissions. Does that help?
                        IT is working on it but can't figure out why we can't uncheck "read only". we do it, when we go back it's checked again.

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                        • DAN_M
                          DAN_M commented
                          Editing a comment
                          This is because a file higher up in the hierarchy is set to read only.

                          If your probe file is at "C/My Documents/PC DMIS FILE/PROBE_FILES"... EVERYTHING from your "C drive" to "PC DMIS FILE" to "PROBE_FILES" must all have read only unchecked. If you have a file lower in the chain with read only unchecked but stuff above it IS checked, then minute you get out of the dialogue box it will read up and re-check itself for you! Super annoying.

                          Give yourself full permissions. Then, restart computer. Then, start at the c drive and go all the way down to your probe file and make sure all of the files are NOT READ ONLY. IF you start at the top and work all the way down, it will then stick.
                          Last edited by DAN_M; 11-20-2020, 02:30 PM.

                      • #13
                        What are your speeds and settings for the verification? I'm using an L probe, 50mm extension with a 2x20 stylus and it regularly says .0001-.0002 std deviation.

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                        • #14
                          DAN_M I tried that multiple time-but it keeps going to back to read only. The probe files themselves are not read only, i have admin rights but it still doesn't agree with me. There has to be some security setting that's stopping it from doing what i tell it to do. i let IT find it

                          ctw00 It used to be up to .0002, at worst .0003". it's been almost a week that it's changing. I use Move speed 90%, Check speed 3%-which is what i use when measuring. 23 hits 3 levels

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                          • ctw00
                            ctw00 commented
                            Editing a comment
                            How fast is 100% on your machine? The machine I am using 100% speed translates to 300mm/sec. With my 1x10 probes if I went faster than 1.5% (4.5mm/sec) it wasn't repeatable.

                        • #15
                          ctw00 It's 254mm/sec. i tried making it a lot slower but didn't help too much

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