ISO GPS - Concentricity with reference to a planar face?
ISO GPS - Concentricity with reference to a planar face?
(OP)
Hi,
Firstly, apologies for the bad drawing enclosed (CAD system is currently down)...
Anyway, I was just thinking about something I came across when working at my previous company (a large global leader in fluid control), and would love anothers opinion. Part of my job was to apply GPS to 2D drawings, and this is something I have a few years experience with. One thing I seen at this particular company, which I had never seen before was using a concentricity tolerance, which also referenced a perpendicular, planar face. I have drawn a very basic example of what I typically saw on some drawings, and I was just curious, has anyone ever seen this before?
My understanding is that coaxiality references an axis and concentricity references a point, where only the corresponding axis (or combined axis to make a common axis reference such as A-B) or point is the reference for the tolerance frame. I understand it is normal to add a concentricity tolerance to one diameter axis, which references another diameters axis (for example, a diameters axis referencing datum A as per my sketch), so I thought it was strange to also reference a planar face (datum B on my sketch), which is at 90 degrees to the A axis. I cannot find any examples of this anywhere else (web and reference books).
Please look at the sketch and tell me what you think, as I would love to know if anyone else has seen this (perhaps I could learn something).
Many thanks in advance
Firstly, apologies for the bad drawing enclosed (CAD system is currently down)...
Anyway, I was just thinking about something I came across when working at my previous company (a large global leader in fluid control), and would love anothers opinion. Part of my job was to apply GPS to 2D drawings, and this is something I have a few years experience with. One thing I seen at this particular company, which I had never seen before was using a concentricity tolerance, which also referenced a perpendicular, planar face. I have drawn a very basic example of what I typically saw on some drawings, and I was just curious, has anyone ever seen this before?
My understanding is that coaxiality references an axis and concentricity references a point, where only the corresponding axis (or combined axis to make a common axis reference such as A-B) or point is the reference for the tolerance frame. I understand it is normal to add a concentricity tolerance to one diameter axis, which references another diameters axis (for example, a diameters axis referencing datum A as per my sketch), so I thought it was strange to also reference a planar face (datum B on my sketch), which is at 90 degrees to the A axis. I cannot find any examples of this anywhere else (web and reference books).
Please look at the sketch and tell me what you think, as I would love to know if anyone else has seen this (perhaps I could learn something).
Many thanks in advance





RE: ISO GPS - Concentricity with reference to a planar face?
It would have certain meaning, if was referenced as primary datum feature, that is, if coaxiality callout was |COAX|dia. 0.1|B|A|.
Side not: diameter symbol is missing in front of coaxiality tolerance value on your sketch.
RE: ISO GPS - Concentricity with reference to a planar face?
RE: ISO GPS - Concentricity with reference to a planar face?
http://files.engineering.com/getfile.aspx?folder=5...
The same is shown in ISO 1101:2012, figure 151, page 80.
RE: ISO GPS - Concentricity with reference to a planar face?
Must admit, I didn't spot that in the ISO 1101 standard, so thanks for finding it. As is mentioned above, concentricity is not really favoured by me over run-out either. However, just so I understand the ISO example (and my own bad example), is the axis on the planar face just trying to say that the 0,1 toleranced axis is central to the planar face of datum B? Isn't the reference in the tolerance frame already saying this by referencing datum A, hence making any reference to a planar, perpendicular face irrelevant? It just still seems a little confusing to me to reference a planar face.
Many thanks again for your input.
RE: ISO GPS - Concentricity with reference to a planar face?
http://files.engineering.com/getfile.aspx?folder=4...
Let me know if it helped.
RE: ISO GPS - Concentricity with reference to a planar face?
RE: ISO GPS - Concentricity with reference to a planar face?
Your sketch and explanation makes us easy to understand, I like it.
Season
RE: ISO GPS - Concentricity with reference to a planar face?
How about an interrupted feature, sure, in ISO all bets are off!
We always look at simple parts and make these simple on purpose the real world is not as neat and clean!! We need standards that will also address the real world parts, IMHO!
Frank