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should it be a runout callout or perpendicularity?

god_paul

Aluminum
Joined
Dec 11, 2013
Location
MI
In the picture below, it is a 30mm diameter small cylinder; the highlighted red color means the bore is machined at this operation.
The face has been machined in the previous operation.

should it be runout callout or perpendicularity?
if it's runout check, we use arbor to locate the part on the bore, rotate the part and the dial indicator checks the face
if it's perpendicularity check, we use air gauge, let the part sit on the air spindle , rotate the part, get the perpendicularity results.

The way we check is kind of reverse check, meaning we are grabbing the bore and checking the face.

This bothers me a while as some people prefer runout but other prepfer perpendicularity...

Capture.jpg
 
The answer is "It depends on what you're trying to control".

Your example shows a CIRCULAR RUNOUT callout. That means the tolerance zone applies to each individual circular element of the surface, independently. In other words the surface could be conical and still meet the CIRCULAR RUNOUT tolerance.

The PERPENDICULARITY callout means every element (point) of the surface must be within the tolerance zone. Therefore the surface must be flat within the tolerance limit as well as perpendicular to -A-.

If you were to use a TOTAL RUNOUT callout, it would be equivalent to the PERPENDICULARITY callout in your example.

IMO, CIRCULAR RUNOUT and PERPENDICULARITY are not equivalent in your example.

IMO, TOTAL RUNOUT and PERPENDICULARITY would be equivalent in your example.

All above based on ASME Y14.5M-2009 (and all previous revisions back to 1974).
 
Perpendicularity makes sense to me. I see that type of callout a lot.

I've never seen runout called between two features like that, although that also means I have no corroboration as to if its allowable or not.
 
True position could define requirements much better for round holes, probably preferable
 








 
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