AUTO circle start and end angle

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  • AUTO circle start and end angle

    I have just noticed something and wanted to know if I am doing something wrong, have a setting wrong or whether this is a bug.

    v3.7mr3
    No CAD
    Measuring an arc from 15º to 165º using 6 points in the X/Y plane.
    No settings for pitch, depth, or height.
    The start and stop angles are not the 15 and 165 that I asked for in the autocircle, they are consistantly 18º for the start and 162º for the end. In other words, the included angle of the arc is small by about 6º.

    Is there an some "offset from end" type of setting that I am overlooking??
    Links to my utilities for PCDMIS

  • #2
    It is probably because the number of hits you specified will not divide evenly into 150º (165-15). It moves the hits in a bit to evenly space them. Probably safer than moving them out a bit and risking hitting a flat or missing the part altogether.

    The number of hits specified is most likely a divisor of 144º (162-18).
    Last edited by #2#; 03-05-2007, 01:45 PM.

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    • #3
      Originally posted by Goodluck View Post
      It is probably because the number of hits you specified will not divide evenly into 150º (165-15). It moves the hits in a bit to evenly space them. Probably safer than moving them out a bit and risking hitting a flat or missing the part altogether.

      The number of hits specified is most likely a divisor of 144º (162-18).
      That is possible. I was expecting that it would take the start and end angle and divide the points into that and come up with the spacing angle from that. I had the same problem with 4 hits instead of 6 although the offset angle from the end seemed to be bigger.

      I thought that maybe it was offsetting from the edge of where CAD model would be if I used one.
      Links to my utilities for PCDMIS

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      • #4
        Originally posted by cmmguy View Post
        That is possible. I was expecting that it would take the start and end angle and divide the points into that and come up with the spacing angle from that. I had the same problem with 4 hits instead of 6 although the offset angle from the end seemed to be bigger.

        I thought that maybe it was offsetting from the edge of where CAD model would be if I used one.
        Try using 15 hits or 10 (both divide nicely into 150). See if it moves them then.

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        • #5
          pc-dmis will start and end I think it is 2 deg. short of the starting and ending of a auto circle.That is built into the software.I believe that only happens on a not complete circle.
          Last edited by JIM HARRIS; 03-05-2007, 02:02 PM.

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          • #6
            Originally posted by Goodluck View Post
            Try using 15 hits or 10 (both divide nicely into 150). See if it moves them then.
            Ok, I think I found what is going on.
            When I change the hits in the autocircle window(f9) it is not calculating the start and end correctly, but if I turn on show hits and parameters in the regular edit window and make the changes in the edit screen then it calculates them right.

            I can get this to duplicate over and over now. It is a bug from what I can tell.
            Links to my utilities for PCDMIS

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            • #7
              Greetings,
              I believe both Jim Harris and Goodluck are correct. The two degrees that Jim refers to can be found in the help menu for create an auto circle under properties box, start ang box. DMIS will always leave at least two degrees at the start and end of an arc. Never less than two degrees. Then it will divide the hits evenly on the arc. If you have a 180 degree arc 0-180 with five hits it will start at exactly 2 degrees and end at exactly 178 degrees. 180 -4 = 176 divided by 4 (the spaces between 5 hits) = 44 degrees between hits. I have found this to be true with or without CAD.
              John

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              • #8
                Originally posted by JohnCTB View Post
                Greetings,
                I believe both Jim Harris and Goodluck are correct. The two degrees that Jim refers to can be found in the help menu for create an auto circle under properties box, start ang box. DMIS will always leave at least two degrees at the start and end of an arc. Never less than two degrees. Then it will divide the hits evenly on the arc. If you have a 180 degree arc 0-180 with five hits it will start at exactly 2 degrees and end at exactly 178 degrees. 180 -4 = 176 divided by 4 (the spaces between 5 hits) = 44 degrees between hits. I have found this to be true with or without CAD.
                John
                Ok, I finally found what you are talking about. Thanks for pointing that out. Funny thing, what I said earlier about it doing it "right" from the edit window vs the dialog box holds true 50% of the time. It does it right sometimes and not other times. So it is inconsistant.

                I find this to be a stupid override of what I am asking for. I read the description about the offset having to do with CAD, but I would expect them to offer a setting that allows you to define the amount of offset from the edge of the CAD feature and not use some arbitrary amount especially when you are not using CAD.
                Last edited by cmmguy; 03-06-2007, 03:16 PM.
                Links to my utilities for PCDMIS

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