Hole position - angled surfaces

[dgallup]

I have a stamped bracket that has a number of holes as well as semi-circles that have to be maintained in position relative to each other. This would be pretty trivial if the part were flat but it is has two 15 degree bends.

That attached drawing is not complete, so don't get upset over the overall shape. I just want to know if you think this is a valid use of true position on the holes and semi-circles.

 

[dgallup]

OK, as soon as I looked at the first file I saw a couple of glaring errors so here is a better files, still incomplete. Let me know what you think.

 

[drawoh]

dgallup,

Your datum_E should be applied to the hole, not to the centre line. This is the case at least with ASME Y14.5. Unless I have a confusing, multi-page drawing, I specify the tolerance in one place, only. E and F should be shown as datum boxes pointing at the faces of the two holes.

I can interpret your drawing to ASME Y14.5.

I generally assume you can locate a hole from a sheet metal bend to ±0.4mm. Any tighter than that, I want to chat with my fabricator. You defintely are tighter than that.

JHG

 

[pmarc]

The answer to your question depends on which GD&T standard you are following, ISO or ASME.
- if ISO, you can apply position to holes and to semi-cirles;
- if ASME, you can use position for holes, but you should rather go with profile of surface control for semi-circles since Y14.5 "reserves" position tolerance for features that have opposite elements(features of size). Some folks will probably say you can go with positon for semi-circles. (There was actually a hot discussion some time ago about this issue, but as far as I remember no agreement has been achieved.)

Nevertheless I agree with drawoh that you should avoid placing datum feature symbols on axes.

 

[dgallup]

Thanks. Using ISO, in this case ISO 1101 which allows the use of the axis if it is of a single feature.

My biggest concern is how the position is going to be inspected for the holes and semi-circles on the 30 degree surface.

 

[SeasonLee]

I am with pmare that the position control is used to locate FOS, a semi-circle doesn’t have opposed points, profile control is a better approach, you may get more detailed information from this link.

http://www.tec-ease.com/gdt-tips-view.php?q=147

SeasonLee

 

[CheckerHater]

Just out of curiosity: How the mating part(s)look like?
I have strange suspicion that drawing does not fully represent design intent (as in what is attached to what and how?).

 

[dgallup]

Here is how it looks now. I've blanked out all the drawing format, general notes & identifying info so it looks incomplete. There is a general "unless otherwise specified" surface profile GDT.

Here is an assembly jpeg with just the bolts & manifold it bolts to. There are devices that fit in each of the pods that the retainer holds down against an internal pressure of 120 PSIG.