Perpendicularity tolerance as refinment of Concentricity tolernce 2

[waqasmalik]

Is perpendicularity tolerance is a refinement of concentricity and symmetry tolerance?
To me, perpendicularity tolerance is a refinement of position tolerance, run out and profile of surface.

 

[CheckerHater]

If you can create concentricity or symmetry requirement, where tolerance zone is perpendicular to datum axis or plane, then you can use perpendicularity as well.

But I have my doubts.

 

[pmarc]

In my opinion, if one wants to apply perpendicularity tolerance in addition to existing concentricity or symmetry callout, the value of the perpendicularity tolerance shall not be greater than the value of the concentricity/symmetry tolerance.

 

[CheckerHater]

I guess so, but will it create a refinement, as in wrt the same datum(s)?

Imagine perpendicularity to A added to Fig.7-60 or 7-63 in 2009

 

[ewh]

It is not just your opinion, pmarc...;-) it is just plain common sense that it would be pointless to add a refining tolerance which is larger than the initial tolerance (which would provide the same type of control).

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[ewh]

If the cylinder that the concentricity contol is relative to has a perpendicularity control, you would have to add the two tolerance zones (which may be larger than your requirements) to determine what perpendicularity control you end up with. Then an additional perpendicularity control would be a refinement. If there is no initial perpendicularity control, adding one would be not be a refinement but an additional control.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[pmarc]

I guess so, but will it create a refinement, as in wrt the same datum(s)?

I would say this is not "classic" refinement since the two callouts (ASME concentricity and perpendicularity) can't really use the same datum feature references.

But even if we imagine (just for the purpose of theoretical exercise) that in fig. 7-60/2009 right face of the datum cylinder was assigned as datum feature B, and a perpendicularity callout wrt B was applied to the smaller cylinder in addition to the existing concentricity callout, I think that anything more than 0.1 in this perpendicularity tolerance would me meaningless. Futhermore, since the right face (assigned as B) would also have to be controlled by a perpendicularity tolerance to datum axis A in order to avoid incomplete drawing specification, I think the perpendicularity tolerance value for the smaller cylinder wrt B would have to be even less than 0.1 to make any sense.

Besides, why would somebody even want to combine perpendicularity with concentricity in reality? Unless we are in ISO world - then, using my modified version of fig. 7-60, concentricity to |B|A| and perpendicularity to B for the smaller cylinder would work.

 

[waqasmalik]

Attached figure has been taken from Alex Krulikowski book of "GDT Fundamentals".
At serial number 6 it is written that perpendicularity tolerance must be refinement of any other geometric control that control perpendicularity of the feature.
Does concentricity control the perpendicularity? With respect to what datum reference?

 

[pmarc]

Waqasmalik,
Concentricity does not control perpendicularity.

 

[waqasmalik]

Then how perpendicularity is a refinement of concentricity?

 

[ewh]

Concentricity is relative to a "parent" cylinder, and perpendicularity would be a refinement relative to that cylinders orientation.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[waqasmalik]

I am not following.Plz elaborate
Thanku

 

[CheckerHater]

Me too.

Also, what about "ISO world"?
I know in ISO concentricity is also named "coaxiality", but I've never heard about ISO allowing features to be coaxial and coperpendicular at the same time.

 

[ewh]

You have a cylindrical feature (datum B) perpendicular to datum A (flat surface) to within .010.
You have another cylinder that is concentric to datum A to within Ø.010.
This gives the second cylinder a resulting perpendicularity zone of .020 relative to datum A.
If you need the second cylinder to be controlled more tightly, you add a refining perpendicularity requirement (less than .020).

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[waqasmalik]

Alex has clearly written that as you can see in the figure i have attached.
"Is the tolerance value a refinement of other geometric tolerances that control the
perpendicularity of the feature?
(e.g Position tolerance, circular run out, total run out, profile of a surface, concentricity, symmetry)"
So concentricity is included amongst those geometric controls that controls perpendicularity.But how?

 

[CheckerHater]

You have a cylindrical feature (datum B) perpendicular to datum A (flat surface)
You have another cylinder that is concentric to datum A

How that another cylinder is concentric to flat surface?

 

[ewh]

Got me... that second cylinder should be concentric to datum B, not A.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[waqasmalik]

Thanx ewh.I was not thinking that way. I would like to ask some more questions.
"Total run out controls perpendicularity" as it is written in the figure attached.
Will the perpendicularity be controlled if i apply a total run out to surface constructed around datum axis?.See figure 9-3 in ASME Y14.5M 2009.

 

[waqasmalik]

I think total run out will control perpendicularity for the surfaces which are constructed normal to the axis

 

[axym]

wagasmalik,

I think it is possible to envision a case where a Concentricity tolerance indirectly controls Perpendicularity. Here is a possible scenario:

-Datum feature A is a planar surface
-Datum feature B is a cylindrical surface, nominally perpendicular to datum feature A
-The toleranced feature is a cylindrical surface, nominally coaxial with datum feature B (and hence nominally perpendicular to datum feature A)

The following Concentricity tolerance is applied:

CON|Dia 0.1|A|B|

This tolerance would indirectly control how tilted the toleranced feature's axis could be relative to Datum A (hence indirectly controlling Perpendicularity). I'm not sure if it would be controlled within the same value as the Concentricity tolerance. I haven't thought through the possible scenarios - perhaps others can help here.

Y14.5 does not show an example with a plane/cylinder datum feature combination in the Concentricity section, it just states that there needs to be a datum axis. The plane/cylinder datum feature combination is shown in the runout section, which also states that there needs to be a datum axis. So I don't see a reason why the same datum feature combination couldn't be applied to Concentricity.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca