THREADS IAW FED STD H28A ???

[CAD_Man]

Our engineering drawings state "THREADS IAW FED STD H28A" in the tolerance block.

My question is... WHY? I've asked around and since it out dates most of the people here, nobody seems to know why.

If we removed it, it would envoke ASME Y 14.100 which references 14.6 which references ASME B1.X and FED STD H28. So why do we call it out on the drawings?

Any thoughts?

Chris Wilson
Engineering Services Manager

Certified SolidWorks Professional
Certified Enterprise PDM Administrator

 

[Sparweb]

Well, it may make it sound like specifying that a Hex-bolt head shall have "6 points AND 6 flats"...
The drawing is probably making explicit the thread standard, rather than let it be implicitly assumed to be H28 or ASME B1.*
FYI, the Foreword in the Fed-STD-H28 explains the difference between H28 and ASME B1.7, including:
"Added international ISO standard metric terms, and replaced thread diameter symbols with ISO standard symbols."
So hardly an earth-shaking difference and you will be able to delete the reference, especially if you say that the drawing says to interpret per ASME Y14 already.

As for how it got on your drawings in the first place, only the former inmates of the asylum can answer that, but they've escaped already...

STF

 

[3DDave]

It certainly short-cuts the need to buy every one of a series of standards if the one at the end of the pile is the only one that is needed and is available for free.