Perpendicularity or TIR?

[rinkman11]

Hello all,
Perpendicularity or TIR that is the question.
A conveyor tube runs thru the center of several donuts. When the tube starts its rotation the faces of these donuts have wobble in them. An indicator is used on the face of the donut to check the variation of wobble. Is this perpendicularity or TIR?

 

[ornerynorsk]

Axial runout would be the more correct term rather than perpendicularity.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[BrianE22]

An indicator would be measuring TIR. TIR would include all effects (perpendicularity + flatness + probably other stuff).

 

[is2634]

Both "Perpendcularity" and "Total Runout" can be used to specify control of the geometry you describe per ASME Y14.5M-1994 (see sections 6.6.4 and 6.7). Therefore both can be correct. The best resolution is to have it specified clearly on a drawing and linked to a national standard definition.

TIR is typically an abreviation for "Total Indicator Reading" or better described as FIM "Full Indicator Movement". Some refer to TIR as "Total Indicated Runout". None of these terms officially control geometry per the standards. However, many people use TIR to describe "Total Runout", which leads to confusion.

My guess is you are actually measuring "Circular Runout"
1. If the indicator tip remains fixed at one radial position then the proper terminology is Circular Runout.

2. If the indicator tip is slid in and out radially and that sliding action is constrained in both axial position and perpendicular to the rotating axis, the proper term is Total Runout.

3. If the indicator tip is slid in and out radially and that sliding action is NOT constrained in both axial position and perpendicular to the rotating axis, the proper term is Circular Runout(i.e. several measurements of scenario 1)

See ASME Y14.5M

 

[ornerynorsk]

What the OP is describing in his precise situation is axial runout.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[is2634]

I agree that many would call this axial runout, but "Axial Runout" is not defined in the standard either.

"Circular Runout" specified with a drawing pointing to the desired surface is the most complete definition.

 

[BillPSU]

The indicator reading will be TIR or total indicator reading. You will be measuring the total affect of all variations causing the TIR.

 

[Tmoose]

Are the donuts fixed to the shaft, or is each donut a stationary support bearing with the shaft rotating inside?

I'm guessing the donuts are NOT bearings.

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this device is fixed to a rotating shaft.

http://www.technologystudent.com/images5/swcam2.gif

It looks to be made from a flat plate mounted non-perpendicular to the shaft.

A device could be made to create similar axial motions (runout) as it rotates such that every radius is very perpendicular to the rotating axis.

This device is designed to create axial motion (has runout)

http://i.ebayimg.com/19/!Bn56J0Q!mk~$(KGrHqEH-CMEtr!Iw4nPBLl(OILTDQ~~_3.JPG

the sides of the grooves in this shift selector drum could all perpendicular to the shaft.

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The surfaces that from the had of this valve for a 4 stroke engine could have very low axial runout ( single arrow symbol )

http://www.autohausaz.com/secure/PartImages/028109601D.jpg

But there is not a perpendicular surface to be found.

Specifying low Total runout ( double arrow symbol ) would turn the valvw into this.

http://bearsperformance.com/canada/images/40spline-spool.jpg

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I think Either total runout ( 2 arrows ) or flatness and runout of teh donut mounting face would give you what you want.

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long shot that I would still check - the donuts are fine, and the shaft is bent. Shaft bend can exist on the naked shaft or be induced by components mounted on it.

real life example of a bend-inducing component - a long hub with a relieved section in the bore, retained by setscrews placed in a relieved section of the bore. tightening the setscrews bends the shaft.