runout relative to same feature's axis
runout relative to same feature's axis
(OP)
Hi,
I am working on a legacy drawing that I am reviewing for GD&T correctness. This part is a shaft that is calling for circular runout on the OD surface referenced to shaft dia as reference datum(please see the attachment). I know better ways of controlling this shaft but I can only change it if it is against Y14.5. I can't question the design intention because they were making these parts before???
Is there anywhere in Y14.5 that prohibits using axis of same cylinder as ref for run out control of its face?
I am working on a legacy drawing that I am reviewing for GD&T correctness. This part is a shaft that is calling for circular runout on the OD surface referenced to shaft dia as reference datum(please see the attachment). I know better ways of controlling this shaft but I can only change it if it is against Y14.5. I can't question the design intention because they were making these parts before???
Is there anywhere in Y14.5 that prohibits using axis of same cylinder as ref for run out control of its face?





RE: runout relative to same feature's axis
I would suggest changing that to roundness but make sure the roundness tolerance is inside the size tolerance range. It the size tolerance is +/- .010, then the roundness must be no more than .020 and probably, much less.
If this is the complete drawing, then one does not need a datum on the OD.
Dave D.
www.qmsi.ca
RE: runout relative to same feature's axis
I agree with you regarding the callout. I just can't find the item in ASME that backs it up.
I am dealing with a tough checker and definition of runout is not clear on this issue.
Thank you,
Kaveh
RE: runout relative to same feature's axis
"Where features to be controlled are diameters related to a datum axis, one or two of the diameters are specified as datums to establish the datum axis, and each related surface is assigned a runout tolerance with respect to this datum axis."
I have only seen runout of a datum surface controlled relative to itself in the case of two datums establishing a datum axis collectively, but the above quoted paragraph seems to allow a surface runout relative to the surfaces axis.
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RE: runout relative to same feature's axis
RE: runout relative to same feature's axis
RE: runout relative to same feature's axis
Roundness and straightness could be combined in a cylindricity call out and it would be comparable to total runout if we had 2 diameter on the same axis.
Dave D.
www.qmsi.ca
RE: runout relative to same feature's axis
RE: runout relative to same feature's axis
"Each considered feature must be within its runout tolerance when the part is rotated about the datum axis. This may also include the datum features as a part of the runout tolerance control where so designated."
The diagram pointed out by kmansoor supports this. The circular runout tolerance on the Datum D feature references Datum D.
I can't say that I understand why this is allowable or why anyone would use this technique.
I agree with TheTick that if datum targets near the ends of the feature were specified, then the runout of the remainder could be checked. If datum targets were not specified, however, it doesn't make sense to me.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: runout relative to same feature's axis
It might be legal to specify but as you said parts are being produced from quite some time how is quality inspection been done with this kind of condition.