circular runout - part gripped at hex

[rotty1974]

Regarding circular runout. Ifi have a cylindrical part that contains an internal hex, where should the datum reference be applied. If the part was being gripped at a hole instead of a internal hex i would choose the inside diameter as the reference. Does anyone have any knowledge as to what to do regarding a internal hex instead of a hole? Thanks in advance.

 

[dept664]

rotty,


Any feature of size may be used as a datum, even a hex. Apply your datum to the hex just like you would have a round hole. It will mean that your inspector(s) will have to build a hex-shaped arbor, or use a Cordax machine to inspect the part.


Gary