So you are asking what the minimum radius is for the 'R6' bend?
Tricky. The 'R6' is not indicated as basic from what I can see - so it's debatable if the 'unless other wise specified' surface profile really can be used on it.
However, if you assume the 'unless otherwise specified' note is also meant to imply that all dimensions are basic, then you'd apply the 4 surface profile and your minimum radius would be 4, but this is making a big assumption.
This drawing has a lot of issues and appears to be prepared by someone that doesn't have a good understanding of GD&T or general drawing principles.
The way the 'B' and 'C' are labeled and then used looks questionable.
Also - all the [0 1], [0 2] & [0 3] are confusing to me, why are they not just 0?
Sorry, the title block had to be cut off for confidentiality reasons. All dims are basic unless otherwise specified. Assuming that the profile tolerance does apply to the bend radius, would it be treated as a ± dimension making the radius 6±2, or would it be treated as a standard profile tolerance making it a bilateral zone equally offset in both directions from the theoretical perfect?
It would be treated as a standard profile tolerance making it a bilateral zone equally offset in both directions from the theoretical perfect.
However, simplistically in this case that's equivalent to 6+-2 unless I'm over looking something.
It's not a controlled radius so the surface could bobble back and forth a bit.
Though, that said, I based my comments on my understanding of ASME Y14.5M-1994 - if you're using a different standard that might make a difference because of rule 1.
We are using ASME Y14.5M-1994. I have attached another drawing showing my concern. We used a 3mm punch to form the parts, which does not fall within 6±2, but as shown in my drawing it falls within the 4mm zone established by the profile. Do I have the wrong understanding of how profile tolerances work, or would this be acceptable because the radius falls within the established zone?
Anyway, your interpretation is correct. Bend radii are more commonly toleranced directly with +/- unless the bend itself also has to nest with a mating surface. Depending on stress concentration issues, etc, you may want to make it a CR (controlled radius).
I'm in accord with Kenat that the GD&T overall is badly done. Datums B&C are not valid because they don't invoke the boundary, but rather just the radius; i.e. it's not really a feature of size other than at the tangencies. This looks like an adjustable corner bracket; more typically the face perpendicular wrt datum-A would be called out as the secondary datum feature and the length would be called out as the tertiary datum feature of size. Then, the holes & edges & such would be located wrt those datums. Lots of assumptions on my part, but the part looks just like a corner bracket for securing a table top to the skirt trim, with lots of adjustability designed in.
I see, it's the aspect not covered by 'simplistically' that you're questioning. You're right, since the profile also allows shift of the location of the radius as well as it's size you could get a small rad pushed into the corner.
This would be allowed per my understanding of the drawing.
It may not be what was intended if they were trying to prevent cracking etc.
