Reporting True Position of multiple holes

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armymachinist
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Reporting True Position of multiple holes

Post by armymachinist » Tue Apr 21, 2020 5:42 pm

New CMM user here. I am having problems reporting true position of circular patterns of holes. I am guessing that I am either missing a step while programming, or doing something out of order. True position is reporting up to .004" out of tolerance but if I report the X,Y locations of the same holes, they are not more than .0005" off of the nominal locations.

I've tried several different programming strategies with the same results. My most recent program I have two separate bolt circles. One has 8 holes, with an individual true position callout of .001, the other has 6 holes, also with individual true position callouts of .001. I programmed this part with circular hole patterns. My nominals are all correct, as well as the angular placement of each circle. In the past I have programmed similar situations in joystick mode, establishing each feature manually. Neither strategy has given me what I need.

I am trying to report the true position of each circle. I have read somewhere on here that this might be incorrect, that a point should be used for true position. Any help would be appreciated. I have attached a pdf showing what I have going for a program.
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CrashN8
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Re: Reporting True Position of multiple holes

Post by CrashN8 » Wed Apr 22, 2020 9:35 am

First an obvious (maybe) question... Are you using the same nominal (Basic) values for both True Position and Location outputs? I guess this is reason for large difference. To me, it sounds like you should be using Composite Position. Please search Help Files for Composite Position to see if this is indeed useful for you.

armymachinist
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Re: Reporting True Position of multiple holes

Post by armymachinist » Wed Apr 22, 2020 10:47 am

I looked through the basic values for the features and the reports. All are the same. I will try using composite position to see what happens. I've attached screen shots from one of the features.
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CrashN8
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Re: Reporting True Position of multiple holes

Post by CrashN8 » Wed Apr 22, 2020 11:40 am

Is this feature a Circle or Cylinder? If it's a Cylinder, the actual could be tilted slightly, thus explaining larger(er) Position deviation.

If you continue to struggle please email your Project file to US Help Desk for assistance.

Ortega H
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Re: Reporting True Position of multiple holes

Post by Ortega H » Tue Apr 28, 2020 11:46 am

ARE YOU USING CARTESIAN OR POLAR NOMINAL POSITION
FOR MOST BOLT CIRCLES ARE CIRCULAR PATTERNS I START WITH CARTESIAN (BECAUSE ITS THE DEFAULT) BUT END UP SWITCHING TO TO POLAR

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