Runout Tolerance Applied on an Assembly 1

[greenimi]

Why runout is used in this figure? (instead of profile)

What would be the difference between using profile (maybe even with dynamic profile modifier) instead of currently shown total runout?
Are there any mathematical difference between shown total runout and profile (again with dynamic profile maybe) ?

 

[mfgenggear]

Let's break this down a little.
Runout and total runout is generally but not always use with a spinning rotating surface, eg shafts, rotating disk, gears, bearings ect.

Total runout is used to control taper, runout on the entire surface. A ground bearing surface. Which the shaft is ground with a rotating grinding wheel.
Runout does not control taper.
But the enter diameter or face.
Must adhere to the runout.

Both are use for rotating hardware.

Axis for this rotating generally is controlled with two or more datums. This is how it works in real life.
Profile is generally not used on rotating hardware. And the parts must be located on the datum while verifying runout. With a dial indicator. It is a face and simple measuring tool.

 

[mfgenggear]

I would like to add runout is the preferred method for very precision ground bearing surfaces.

 

[Burunduk]

12.6.8 Runout Tolerance Application on an
Assembly in ASME Y24.5-2018 adds an exception to the rules, but it doesn't change the rules. On a detail drawing runout must still reference the axis the surface is constructed around as a datum.

 

[greenimi]

Honestly, the 2018 version did not make the world a better place.

Yes. I agree. Was released to make some $$$$ for ASME organization.
The pressure the organization put on the committee to release something finally had its effects

 

[greenimi]

Assembly in ASME Y24.5-2018 adds an exception to the rules, but it doesn't change the rules. On a detail drawing runout must still reference the axis the surface is constructed around as a datum.

Burunduk,
If you go that route by not having the datum axis in the FCF, then I think you risk of having a runaway train.
The specification will be fraught with ambiguity which is exactly what a standard is meat to prevent.
So, my preference is to use dynamic profile with customized DRF -as you suggested - and forget about runout ON THIS assembly example (do not extrapolate my replay more than it's stated)

 

[CheckerHater]

There is no chiseled in stone rule how exactly feature has to be fixtured to produce datum axis. Shaft being installed on bearings inside of a motor, pump, etc. is no better and no worse than shaft installed on v-blocks.
It looks like using GD&T on assemblies is a next big thing, and Fig. 12-16 is only the beginning, so brace yourself everybody!

 

[3DDave]

I'd rather see profile of surface be the only control available. It can be extended to mean midplane or median axis as well. With enough creativity and some amount of squinting it is the universal solution to all tolerance problems. This will be a boost to those who make volumetric point cloud inspection equipment and we can finally ditch the old-fashioned dial indicators and calipers.

 

[greenimi]

It looks like using GD&T on assemblies is a next big thing, and Fig. 12-16 is only the beginning, so brace yourself everybody!

Then I think belong here, not in Y14.5.
Adding such a confusing assembly as the last picture into the last chapter (of the Y14.5) does not help at all.
Sorry, mathematical rigor and standard consistency is not Y14.5's committee strength.................... looks like.

 

[greenimi]

How this is a consistent approach with Y14.5?
Or looks like everyone is doing whatever they want, right?

 

[mfgenggear]

ha almost every machinist and mechanics tool box ihas eighter a mag or indicator stand with an assortment of dial indicators.
most rotational shafts are held between centers , manufactured and inspected between centers. all diameter runout or adjacent faces are verified with dial indicators. it is a very fast and inexpensive
measuring method. try to obsolete that and
every machinist will revolt.

 

[mfgenggear]

a machinist can not stop production just to take a part to a cmm to verify their part.
every machinist has v blocks, centers, or some type small fixture tooling on their bench. master gear setup up with bench tooling. or a surface plate. to measure parts
with inspection equipment. people really need to spent some time in the factory.

 

[Burunduk]

Greenimi,
What do you find ambiguous about 12-16?
I personally don't see any ambiguity.
The measurement set up will be based on datum feature simulators interfacing with the bottom base (A) and 2 pins (B). Be it the orientation of the dial indicator practically, or the two-planes and coaxial-cylinders tolerance zones theoretically, it's rigorously defined. The thing about the rotation axis - if it's a single part you need to constrain it by a datum feature simulator as indicated in the FCF or the requirement is ambiguous. If it's an assembly, that's a different story - you have no affect on it because the practical "datum feature simulator" for the rotation axis is within the assembly you are inspecting. And the requirement is actually between components and not between features in a single component, that's why requiring a relationship of the wheel to the base structure makes sense.

 

[greenimi]

ha almost every machinist and mechanics tool box ihas eighter a mag or indicator stand with an assortment of dial indicators.
most rotational shafts are held between centers , manufactured and inspected between centers. all diameter runout or adjacent faces are verified with dial indicators. it is a very fast and inexpensive
measuring method. try to obsolete that and
every machinist will revolt.

Just for clarity: my question has NOTHING to do with the way your machinist/ mechanics/ inspectors are qualifying the requirement (with your indicator stand and with an assortment of dial indicators). They will continue to do so. No change.

My question has mainly to do with the definition of the runout IN THE ASSEMBLY context.
I hope I am clear. So, nobody wants to obsolete anything...don't get to high and excited on this.

 

[mfgenggear]

greenimi
it has every thing to do what is specified on the engineering drawing.
most efficient and precise method for manufacturing, cost efficient to inspect.
ADQP requirements. ISO 9001 requirements .
and more.

 

[greenimi]

or a surface plate. to measure parts
with inspection equipment. people really need to spent some time in the factory.

Yes, sure. “Every man takes the limits of his own field of vision for the limits of the world.”

 

[greenimi]

I personally don't see any ambiguity.

But you don't see any consistency either......Nor with "The definition of runout tolerances was not changed" nor with the AED (2023) standard, right?

 

[Burunduk]

Greenimi,
As I mentioned, I don't think the definition changed. There is an exception added, for assembly drawings.

As for that new standard, I guess if you reference it you would need to add "AG". If you only reference Y14.5-2018 you could skip that symbol. If anything that is an inconsistency or redundancy caused by the newer standard developers and not the fault of Y14.5.

 

[greenimi]

As for that new standard, I guess if you reference it you would need to add "AG". If you only reference Y14.5-2018 you could skip that symbol. If anything that is an inconsistency or redundancy caused by the newer standard developers and not the fault of Y14.5.

But at least the AED standard is consistent with the fact the datum axis is part of the FCF whereas Y14.5 lacks, hence creating great confusion.

If it's an assembly, that's a different story - you have no affect on it because the practical "datum feature simulator" for the rotation axis is within the assembly you are inspecting.

That's exactly what I don't like about the new "addition", being a "different story" !
Different story, but using the same "title" and the same "author"

 

[Burunduk]

Greenimi,
I’ll say this—if you think of "GD&T" as a way to communicate and want it to be an effective one, using runout like in 12-16 is supposed to feel pretty straightforward and easy to understand. On the other hand, throwing in dynamic profile with a custom DRF is basically a guaranteed way to confuse a bunch of people. Sure, they technically mean the same thing, but as you can probably tell, I didn’t exactly take my own advice too seriously.

 

[greenimi]

I’ll say this—if you think of "GD&T" as a way to communicate and want it to be an effective one, using runout like in 12-16 is supposed to feel pretty straightforward and easy to understand.

So giving up definition robustness and consistency for the sake of simplicity is your (and committee's) chosen option, right?
Is this the way a STANDARD supposed to work?
Instead of education (continuous improvement) I will just surrender........