Runout - a Definition

This might sound a simple question I've not been able to find an answer to it on the 'net.

When collet manufacturers etc. quote a runout figure, are the talking about the total deviation (the span of a DTI needle swing) or the deviation from the median.

I suspect the latter - it sounds better.

Cheers

Steve

I have always used TIR, total indicator runout which would mean that a shaft eccentricity of 1 unit TIR would be running 1/2 a unit away from zero. As for claims by sellers, I suspect that the quality ones use TIR, but who knows what the cheapies do. If you want to buy er collets, then check out APT, they sell 4 different grades and you can choose which to invest in.

Edited By old mart on 25/06/2023 20:02:17

Edited By old mart on 25/06/2023 20:02:51

Edited By old mart on 25/06/2023 20:09:02

I think you have good instincts, always assume the most beneficial interpretation.

I interpret "rounout" as TIR while "concentricity" is the axial displacement, but English isn't my first language so please don't take my word for it.

Steve , you may find it useful to raise this question with Coventry Collets Ltd . Trevor.

If you go to the recent thread on identifying collets and follow the link to the old Crawford Collets pages they show the accuracy figure is TIR. The new CC catalogue also shows accuracy as TIR.

Martin C

Rego-fix also use TIR for their ER collets and I seem to remember ARC do too

Thank you, TIR seems to be the standard definition.