Runout using only on a partial radial portion 2

[Madhu454]

Hi ,

ISO 1101 allows use of runout on a partial surface as shown in the attached drawing.

Does this is allowed in ASME ? I beleive there is no such examples given in ASME. But as an extended principle can we use this kind of specification in ASME?

I dont know what is the practical application, but I guess this type of control may be used in Cam design. I may be wrong, just a guess.

 

[PaulJackson]

Madhu454,
Which ISO publication was that example from?
I have not seen that one before.
Paul

 

[CheckerHater]

When it comes to practical applications, there are many partial features around.
For example in tooling and gages they sometimes create diamond-shaped pins ground to two different diameters in X and Y directions.
I think it will be good application of extension principle.
After all you don't see the problem applying Runout to the shaft with key slot in it, and it technically makes "incomplete" surface.

 

[PaulJackson]

Doh... 1101... I'll look it over.
Paul

 

[pmarc]

Madhu454,
No reasons why this should be considered not allowed per Y14.5.
I would just make sure that the angular dimension is basic, and the line (arc) for indicated area is a chain line.

 

[PaulJackson]

Madhu454,
I agree with the others... I had never noticed it expressed in Standards Publications... thank you for pointing it out.

In practice many many designs specify runout to features that have interrupted surfaces ... like the major diameter of an external gear or spline. Some features typically controlled with circular runout don't even have a continuous portion of the surface designed with a common radius from the axis... like the pitch circle diameter of a gear or spline. In practice an inspector chooses a gage pin or ball sized to contact the feature in near the center of its profile (often approximately at the pitch if possible) and the runout is recorded from the MAX and MIN peak measurements over the gage.

Paul

 

[Madhu454]

Hi Paul,

Thanks for your reply.

If I understood your post correctly, you are saying that runout can be applied to PCD of a gear. Is that true?.

As I understood Runout can only be applied to surface elements, and it cannot be applied to imaginary PCD. Please correct me if I am wrong.

If I assume it is legal to apply runout to PCD of a gear, How do we measure it? I did not understood your explanation of measuring it.

Could you please educate me.

 

[CheckerHater]

This may be good start:

http://www.gearsolutions.com/media//uploads/assets/PDF/Articles/inspection0605.pdf

 

[PaulJackson]

Madhu454,

If I understood your post correctly, you are saying that runout can be applied to PCD of a gear. Is that true?.

I said "in practice many many designs specify runout..." over interrupted surfaces and... gears or splines often have a runout control (if not a total composite action control) on the theoretical PCD.

This circular runout measurement commonly applied to the PCD (accomplished typically with a pin or ball touching tooth profiles in the tooth space) is subject to errors in tooth form and spacing as well as the gear's circularity, eccentricity, and orientation with the datum axis.

Legal? Lets just say that the standards have not as yet addressed every measurable practice.

Paul

 

[Madhu454]

Hi Paul,
Thanks for explaining, I understood now.

Also thanks to CheckerHater for sending a good link on basics of gear inspection.

 

[fsincox]

I am not a big runout fan, but, I have to agree with the others. Thanks CH for some useful info, a star for you.
Frank

 

[dingy2]

Reading 9.4.2 of ASME Y14.5-2009, it does not state that the circular feature must be a continuous surface or a full 360 degrees. With that, I would agree that circular or total runout could be applied to a circular feature that is interrupted such as diameter with a key way cut.

Dave D.

http://www.qmsi.ca