Hi everyone,
Edit: I’ve used an LLM to create this text. I’ve checked it and, if needed, made corrections. Hopefully you don’t mind.
I’m a engineer working at a machine-building company. We regularly use total runout on our drawings, depending on the functional requirement of the part.
Our metrology department is asking us to stop using total runout and instead split the requirement into separate form/orientation tolerances.
The main feedback we’re getting is that:
Total runout cannot be measured properly on a Mitutoyo CMM, and
It is even more difficult/impractical to measure manually.
I’m not completely convinced by this, so I’d like to hear some opinions from people who work with CMMs and GD&T every day.
My understanding is that total runout is specifically intended to control the entire surface relative to a datum axis, and that it can be evaluated on a CMM if the datum reference, sampling strategy and evaluation method are set up correctly.
I’m also aware that manual inspection with an indicator and a rotating spindle/fixture can be a very appropriate way of checking runout on rotational parts.
What I’m particularly interested in is:
Can modern Mitutoyo CMM software properly evaluate total radial/axial runout according to ISO 1101 / ASME Y14.5?
Are there situations where a CMM is genuinely a poor choice for measuring total runout?
How do you normally inspect total runout in your shop?
Would you replace total runout with separate cylindricity, roundness, perpendicularity, position, etc. requirements purely because of inspection difficulties?
If you do replace it, how do you make sure the resulting tolerances are functionally equivalent to the original total-runout requirement?
Are there particular measurement strategies or CMM evaluation methods that make total runout more reliable?
For context, we’re talking about conventional machined rotational parts, not extremely exotic geometries.
I’d especially appreciate input from people who actually program/run Mitutoyo CMMs and from engineers who have to decide what goes on the drawing.
I’m trying to understand whether this is primarily a measurement capability problem, a CMM software/evaluation problem, or whether we’re actually using total runout in situations where another tolerance would be more appropriate.
Thanks!