GD&T Question
GD&T Question
(OP)
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See picture above(which hopefully posts)
I'm trying to use GD&T to tolerance the flats of the D-hole. What I'm trying to describe is the flats centered on the 1.125 diameter hole.
I also have to do something similar with the shaft that fits through this hole.
Position tolerance I have doesn't feel quite right. What are your thoughts?
Thanks,
Pete
]See picture above(which hopefully posts)
I'm trying to use GD&T to tolerance the flats of the D-hole. What I'm trying to describe is the flats centered on the 1.125 diameter hole.
I also have to do something similar with the shaft that fits through this hole.
Position tolerance I have doesn't feel quite right. What are your thoughts?
Thanks,
Pete





RE: GD&T Question
However, simplistically what you have appears to work.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: GD&T Question
I think I could put the flats +/-0.125 along the 4.13 (foot?) long axis and even rotate them as long as they are 0.875 apart, since there is no dimension for a "true position" to datums D or B.
I'd say I would >need< to shift it the full 0.125 to create a D hole. Two flats is sometimes called a double D.
http://www.hartco-eng.com/shop.php?category=35
Will you be using the shaft/hole diameter tolerance to locate the shaft? Are the flats expected to allow the shaft to transmit torque to/from the link?
RE: GD&T Question
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: GD&T Question
I guess I could add a parallel to B control, but it seems sufficiently implied and defined in the position control with B referenced as a third datum - and is frankly not that critical if the Double-D got rotated, so long as it is centered.
-Pete
RE: GD&T Question
With normal +- dimensions you don't get to assume alignments or symmetry because there is no tolerance given on how alligned or symetric etc they need to be. See 2.7.3.
However, when you're using position or similar controls you can sometimes assume symmetry or alignment etc. (so long as it is clearly implied by center lines or similar) because the position control tells you how far off you can be. See fig 5-4 for a potential example.
So I would argue no you don't need the .438 basic.
You also don't need an additional control on the clocking as you already invoke B in the position fcf.
You would probably get much more input over in the GD&T forum.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: GD&T Question
Thanks for your input. I saw the GD&T right after I posted, but I figured I'd get more flack for double posting than being in the wrong place.
I'm working off Y14.5-2009.
I see what you are saying about not assuming parallelism... If I had dimensioned one of the flats to datum B instead of the hole's center, then I'd have an implied parallelism with B (within the confines of the linear dimension). If I understand it right, yes? But since I'm more interested in the center, I'll leave it to the position tolerance.
RE: GD&T Question
RE: GD&T Question
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: GD&T Question
T tg