[Cl...] Posted April 30, 2019 Share Posted April 30, 2019 OK, some help need from the experts in here. Geometry being evaluated is an OD square. Datum -A- is a vertical OD cylinder underneath, and concentric to it. Surface profile, Unilateral (Nominal contour outside) As part (.253 BASIC) gets smaller, profile gets worse. Cut part towards the high (.2525) profile is good. Why, what is influencing this? Link to comment Share on other sites More sharing options...
[De...] Posted April 30, 2019 Share Posted April 30, 2019 The callout is specifying that there is an unequal profile, a total of 0.003 deviation in profile is allowed with 0.000 being allowed outside the nominal profile (so the only allowable deviation is in the minus stock direction). *Assuming the profile is positioned correctly in relation to the datums* If the part is cut over nominal size its out of tolerance because it has plus stock deviation. If the part is at nominal its perfect. The more it deviates from nominal by getting smaller, the worse it gets until it is out of tolerance due to excessive profile error in the minus stock direction. Maybe I am missing something but it sounds like its doing what it should be doing. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 30, 2019 Share Posted April 30, 2019 Per the ASME Y14.5-2009 standard, your tolerance implies that the profile applies unilaterally into the part .0030". The number to the right of the (U) tells you the amount of the tolerance zone outside of the true profile; in this case it is 0, so all of the tolerance applies into the part. Link to comment Share on other sites More sharing options...
[Cl...] Posted April 30, 2019 Author Share Posted April 30, 2019 Turns out we had a CAD model at .250, instead of .253. Link to comment Share on other sites More sharing options...
[Br...] Posted April 30, 2019 Share Posted April 30, 2019 It looks like you have the tolerance zone backwards. It should be (nominal contour inside). The tolerance zone starts at the nominal profile and goes into the material .003". But your color map appears to show the high limit as a positive number. The color map should show the high limit as 0 and the low limit as -.003 if you have the tolerance zone to the inside. Also, Make sure your model matches the print. If the model size is not exactly .253", you will most likely get false failures. Link to comment Share on other sites More sharing options...
[Br...] Posted April 30, 2019 Share Posted April 30, 2019 Please sign in to view this quote. Then in that case just do a bilateral .003" Profile. 0.250 is the center of the tolerance zone the print calls for. Link to comment Share on other sites More sharing options...
[Cl...] Posted April 30, 2019 Author Share Posted April 30, 2019 I updated the model to .253. Blue is minus mat'l, and the basics are measuring about .251 Link to comment Share on other sites More sharing options...
[Br...] Posted April 30, 2019 Share Posted April 30, 2019 Please sign in to view this quote. So your color map scale looks like this(maybe some different colors)? Link to comment Share on other sites More sharing options...
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