Probes

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  • Probes

    Hallo,
    I have a problem. We have a product with lots of holes that are countersinked. The drawing asks for the concentricity of the countersink to the drilled top hole.
    The drilled hole diameter is 0.370" - 0.380" and the countersink is 0.615" - 0.635".
    To measure this countersink I had to make a special probe. Diameter of special probe is 8.8mm and the shaft has a diamter of 1.4mm (It is the shaft of a standard Renishaw probe 2x20.) The sphere is not completely round, but the top section has been milled off. It is just a little bit more than a half circle. Like a mushroom
    DSC06520.jpg

    When I calibrate the probe PC_Dmis displays an error. When I look at the results, it shows a diamter of 8.6mm.
    The error is because the build up of the probe is not correct. I had to choose a standard tip from the PC_Dmis pull down menu.

    What I want to know is: Can I make my own probe files and import them into PC_Dmis.(Like the option to create a different CMM)
    sigpic If only all problems were so simple

  • #2
    Originally posted by Big John View Post
    Hallo,
    I have a problem. We have a product with lots of holes that are countersinked. The drawing asks for the concentricity of the countersink to the drilled top hole.
    The drilled hole diameter is 0.370" - 0.380" and the countersink is 0.615" - 0.635".
    To measure this countersink I had to make a special probe. Diameter of special probe is 8.8mm and the shaft has a diamter of 1.4mm (It is the shaft of a standard Renishaw probe 2x20.) The sphere is not completely round, but the top section has been milled off. It is just a little bit more than a half circle. Like a mushroom
    [ATTACH=CONFIG]7158[/ATTACH]

    When I calibrate the probe PC_Dmis displays an error. When I look at the results, it shows a diamter of 8.6mm.
    The error is because the build up of the probe is not correct. I had to choose a standard tip from the PC_Dmis pull down menu.

    What I want to know is: Can I make my own probe files and import them into PC_Dmis.(Like the option to create a different CMM)
    Yes you can.
    I have not had to do this in several years, but from memory:

    Pick a probe file that is close to what you want to create and make a copy. Open the file with a text editor like notepad or wordpad. Somewhere on this forum, and possibly in the F1 pc-dmis help directory is a breakdown of what that text means, although you may be able to figure most of it out on your own. Edit as needed to describe the custom probe you have. Once you think you have it right, give it the name of your new tip and copy paste it back into the probe directory. Now you can use it in the probe utilities window to make your stylus build.

    A couple of words of caution:

    TEST TEST TEST make sure you know you are getting good results by measuring some known artifacts similar to the features you will be checking with this probe.

    Be extra careful taking hits with the part of that probe that is above the equator of the sphere. Unless you have a 6way TP-20 probe those hits could be deflecting the tip in a direction the probe cannot register (i.e. away from the probe).

    HTH
    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

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    • #3
      ALSO, quick & dirty....

      Calibrate a good probe so the machine knows where the qual-tool is. THEN, manually calibrate that probe (telling it NO, the tool has not moved) and it will update the data to the length that you have. You should then be able to calibrate it in DCC mode, as long as you get the start/end angles correct for the shape.
      sigpic
      Originally posted by AndersI
      I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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      • #4
        IN the pc-dmis install directory is a file called probe.dat - this contains all the probe definitions.

        Find the closest probe (in the probe utilities window - I think there's a similar one to yours) and note the name.

        Find it in the probe.dat file and cope from the probe name down to the end tip line

        It use to be that you added new probes into this file - but now you're meant to create a new USRPROBE.dat file and add your user defined ones in that.

        Hopefully you'l be able to see how the build up is done, but you specify start and end locations, diameters etc to define your new probe.
        Automettech - Automated Metrology Technology

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        • #5
          Automettech - Automated Metrology Technology

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          • #6
            Hey Guys,
            thanks for the help. I will try your ideas next week. About to take a long weekend off...........
            sigpic If only all problems were so simple

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