Circle Diameters

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  • Circle Diameters

    I'm having an issue with hole diameter in a plastic injection part. The hole is out of round approx. 0.020" I've run a scan of the diameter and exported the results into an .iges file to evaluate it in CAD and that correlates well with the roundness calculation from the dimensioning menu. Another way I have evaluated the diameter is to take 8 hits individual hits inside the diameter and created 4 distances. However, for the part program report that goes out to the customer, I am reporting out a Diameter, based on an auto circle (2.5 dia hole - 32 hits). How is this diameter calculated in an auto circle check? I assume it is an average of the 32 hits. Also, what do you think is the best way to measure and report out the diameter of this circle based on the fact that it is out of round? The customer's preference is for a single dimension on the report. I am thinking the best solution might be to report out the largest diameter using a distance check from 2 opposite points (the wider dimension is always in the same direction) and then report out the roundness using the auto circle feature. Comments or suggestions?

  • #2
    Originally posted by gcunniff View Post
    I'm having an issue with hole diameter in a plastic injection part. The hole is out of round approx. 0.020" I've run a scan of the diameter and exported the results into an .iges file to evaluate it in CAD and that correlates well with the roundness calculation from the dimensioning menu. Another way I have evaluated the diameter is to take 8 hits individual hits inside the diameter and created 4 distances. However, for the part program report that goes out to the customer, I am reporting out a Diameter, based on an auto circle (2.5 dia hole - 32 hits). How is this diameter calculated in an auto circle check? I assume it is an average of the 32 hits. Also, what do you think is the best way to measure and report out the diameter of this circle based on the fact that it is out of round? The customer's preference is for a single dimension on the report. I am thinking the best solution might be to report out the largest diameter using a distance check from 2 opposite points (the wider dimension is always in the same direction) and then report out the roundness using the auto circle feature. Comments or suggestions?
    There are several ways to ahve Pcdmis calculate the diameter of the tip, and they are in the AUTO-FEATURES CIRCLE menu. MAX-inscribed will give you the size of the biggest round pin that can go through the hole, which would probably be the best.
    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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    • #3
      You can select the following for circle diameters.

      Least Squares - The way I understand it it is the average dia.

      Max. Inscribed - The biggest pin that will fit in a hole.

      Min Circumscribed - The smallest ring that will fit around a stud.

      I'd report max. inscribed as it sounds to me as if you have a hole and then dim. the roundness too.

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      • #4
        Originally posted by Matthew D. Hoedeman View Post
        There are several ways to ahve Pcdmis calculate the diameter of the tip, and they are in the AUTO-FEATURES CIRCLE menu. MAX-inscribed will give you the size of the biggest round pin that can go through the hole, which would probably be the best.
        Too quick for me again! How many times has that happened?

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        • #5
          For diameter on plastic........gage pin & keyed in dim.
          sigpic.....Its called golf because all the other 4 letter words were taken

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          • #6
            This forum is like the Hoedeman hotline.

            The problem with the gage pin method is that I don't have a 2.5" gage pin.

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            • #7
              To give you a more accurate description of the part, it is a bore with threads on the lower half. The print gives me a call out for the gage point inside the bore, which is why I inspected it as a circle and not a cylinder.

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              • #8
                Originally posted by gcunniff View Post
                This forum is like the Hoedeman hotline.

                The problem with the gage pin method is that I don't have a 2.5" gage pin.
                WHATTHEHELL kind of lab are you in that you don't have a 2.5" gage pin? Same as me, I guess!
                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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                • #9
                  What you have gage pins...
                  sigpic
                  if you had soap on a rope it would be tied to yer ankle

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                  • #10
                    I'm just happy we have electricity here.....

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                    • #11
                      Originally posted by gcunniff View Post
                      I'm just happy we have electricity here.....
                      Oooohhh, and what sort of thing is THAT?!?!?!
                      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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                      • #12
                        Originally posted by Goodluck View Post
                        You can select the following for circle diameters.

                        Least Squares - The way I understand it it is the average dia.

                        Max. Inscribed - The biggest pin that will fit in a hole.

                        Min Circumscribed - The smallest ring that will fit around a stud.

                        I'd report max. inscribed as it sounds to me as if you have a hole and then dim. the roundness too.
                        What about MIN_SEP and FIXED_RAD?

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                        • #13
                          Originally posted by gcunniff View Post
                          What about MIN_SEP and FIXED_RAD?
                          I'm not sure on those. Try searching this forum or the PC-DMIS help.

                          Anyone else know?

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                          • #14
                            Originally posted by Matthew D. Hoedeman View Post
                            Oooohhh, and what sort of thing is THAT?!?!?!
                            That is that warm, fuzzy feeling you get when the Hooter's waitress walks up.

                            Originally posted by Matthew D. Hoedeman View Post
                            Oooohhh, and what sort of thing is THAT?!?!?!
                            That is what you are creating when you ride that stationary bike that gets the CMM and computer running.
                            When in doubt, post code. A second set of eyes might see something you missed.
                            sigpic

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                            • #15
                              We don't have gage pins either - we have calibrated pin punches that range from .061 - 1"
                              sigpic Life is not a journey to the grave with the intention of arriving safely, but rather a skid in broadside, totally worn, proclaiming WOW What a ride!

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