Position Tolerance of a square feature on a disk
Position Tolerance of a square feature on a disk
(OP)
I have a disk that is inserted in a cylinder. A square sleeve will be inserted and welded to the square bore of the disk and I am trying to center the hole on the disk. Is a position tolerance the best way to do this? I have read that you can use position with any feature, not just a circle. Even though it is a square, the diameter callout still seems correct to me as the tolerance zone.
Otherwise, setting an X-Y tolerance on the distance to the centerline would give a similar result. I guess the only difference there is the square vs circular tolerance zone.
Is this correct? Thank you.
http://files.engineering.com/getfile.aspx?folder=9...
http://files.engineering.com/getfile.aspx?folder=7...
Otherwise, setting an X-Y tolerance on the distance to the centerline would give a similar result. I guess the only difference there is the square vs circular tolerance zone.
Is this correct? Thank you.
http://files.engineering.com/getfile.aspx?folder=9...
http://files.engineering.com/getfile.aspx?folder=7...





RE: Position Tolerance of a square feature on a disk
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Position Tolerance of a square feature on a disk
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
I believe what John-Paul is getting at is how to deal with the form error on part surfaces:
On the irregular hole shown, several different derived axes/centers are possible (as well as several different centerlines for the OD). Given the tight tolerances, the magnitude of the irregularities could be in the same ballpark as the tolerances.
I'm also wondering - why is the location tolerance for this hole so tight, if a square sleeve is going to be welded into it?
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Position Tolerance of a square feature on a disk
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
But ... what is the axis? The center of the AME from the vertical walls and then the center of the AME from the horizontal walls, then taking the intersection of those two planes? Or maybe a perfect square that expands until it hits, what, 3 points? (This seems to be an "irregular feature of size" if I can throw that term in here.)
The standard would normally say in a instance like this to default to the boundary interpretation. Yet the OP doesn't want that because the thing has to be centered in a circular fashion.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
RE: Position Tolerance of a square feature on a disk
There will be a chamfer on the square bore, and on the sleeve, and that is where it will be welded (currently only on one side of the disk).
We currently have a +.002" -.000" tolerance on the circular bore and a +.000 - .005" tolerance on the circular sleeve, so yes, pretty tight tolerances.
Measuring these tolerances relative to the OD seems tough to me as well. The real OD of this part is about 2'.
JNieman, that sounds like my end goal, but all relative to the OD. And yes, I am struggling to come up with best way to convey this.
RE: Position Tolerance of a square feature on a disk
Or locate the OD relative to each width of the square.
RE: Position Tolerance of a square feature on a disk
Can you explain the working of this assembly?
Just wanted to know whether concentricity between disc and sleeve is more important or perpendicularity between sleeve and disc face.
RE: Position Tolerance of a square feature on a disk
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
I'm not sure that your latest possibility works:
-The two directly toleranced width dimensions are not compatible with the profile tolerance (the dimensions should be basic)
-The position tolerance would only apply to one of the widths. I think it would need another position tolerance for the other width.
This gets into several gray areas. I'm not sure what happens when a position tolerance referenced RFS is applied to a width that is controlled by a profile tolerance. It's defined when referenced MMC, using the boundary position concepts, but I'm not sure about RFS.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Position Tolerance of a square feature on a disk
2X applies to both dimension and position. The frame can be moved to the right to make it more obvious, but it won't really change the meaning.
The square has 4 implied basic 90 deg angles and profile controls orientation of square sides to each other.
No, dimensions shouldn't be basic. No, the width is not controlled by profile tolerance.
In fact, when you see profile applied to feature without basic dimensions, it is clear indication that profile controls form or/and orientation.
RE: Position Tolerance of a square feature on a disk
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
I don't specify "true" outline - I don't control "true" outline. But if you see it as possible ambiguity, what will happen if I replace "all around" with 4X ?
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
Based on the other thread, we've apparently established that the size dims of this square slot do not have to be basic dims, even though there is a profile tolerance all around, right?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
Well, I guess we agreed that there is no "absolute" requirement to always have basic dimensions associated with profile.
We also found out that the concept may be confusing for many people.
If we agree that profile can be used to control form, orientation, but not the size, what do you think would be the best way to do so?
It's not a trick question or attempt to start another war.
If we believe something may be right, but confusing, the natural thing to do is to look for better way.
Hense my question from Dec. 1 about only using "4X"
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Position Tolerance of a square feature on a disk
With that in mind, this example of the square slot with all-around profile and non-basic dims seems to be legal per Y14.5. But I still don't have to like it :)
As for your question, yes it does seem to be the only way to control form/orientation but not size for an unusual shape.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
RE: Position Tolerance of a square feature on a disk
Also, feel free to weigh in on the other thread ("must profile be applied to a basic profile?").
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Position Tolerance of a square feature on a disk
Without datum B the form and radial location tolerance of the cone is still defined; what the diameter tolerance changes is the axial location of the flat relative to the cone apex. As such, the profile tolerance does not refine the diameter control at that location.
RE: Position Tolerance of a square feature on a disk
- pylfrm