Runout & True Position

[Jay Gus]

Good morning All.

Question,

Position on 2 cylindrical features,

When inspecting with V-block and dial indicator and get .005 tir, in terms of
true position would the .005 be doubled?

This has always been a discussion with several engineers & operators and need some good input.

Thank you very much, Jay Gus

[#2#]

We had this discussion a while back. I'll try to locate the thread.

[craiger_ny]

0.005 runout on perfect form is 0.005 true position that is the closest "equivalent" anyway. Be careful.

Craig

[#2#]

I couldn't find the thread. But I seem to recall, the conclusion reached agrees with Craig's post.

[Jay Gus]

Thanks Again Guys! Jay Gus

[than_357]

I'd agree, and with the hypothetical perfect everything else considered. True position deviation would be twice the polar radius for the CMM; runout with an indicator would read twice the max offset centerline distance (i.e. you catch half on the low side and the other half on the high side when rotating to get twice the actual offset with TIR). So your answer would be as Craig said- the same for both.

Of course, depending on the reference frame the reverse won't always be true.

Tom H>

BTW- sorry for the late replies, but you're all working a shift ahead of me.