Calling out #00 threads on drawing

[KENAT]

I’m checking a drawing that has #00 threads. (I realize UNM threads are usually preferred but this part is mating with existing components.)

What is the correct way to call this out on the drawing, specifically what thread spec should I specify/reference?

I know a lot of people don’t reference the spec on drawings but Y14.6 recommends doing so (Section 3.2) and normally we reference B1.1, B1.10M or B1.13M as appropriate.

If I understand correctly the thread form is same as unified so should I specify it as an equivalent UNS or specify the threads as American National thread form?

Also at the moment the callouts say #00-96-2B or #00-90-2B but from the below link I understand the thread class would normally be 3B.

http://www.boltplanet.com/zeroes.htm

I’m trying to be careful on the line between pedantry and thoroughness so don’t want to get carried away but at the moment the drawings says “SCREW THREADS TO BE IN ACCORDANCE WITH ASME B1.1.” which is technically incorrect as all the threaded holes are #00.

Any suggestions?


KENAT, probably the least qualified checker you'll ever meet...

 

[fcsuper]

Wow, you are almost in the turf where you are spec'ing your own threads. You might need to be very specific, especially if the old American National standard wasn't specific.

There a methods used in UN threads that if employed may allow the threads to follow the standard even if they are not mentioned in the standard. I don't have access to the thread standards, so I can't check to see how thread forms are calculated (other than generalities coverd in the Machinery's Handbook)

Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group

 

[KENAT]

That's the UNS I referred to, S stands for special (ASME B1.1 -2003 section 6.4 especially). I'm depressingly familiar with special threads to UN form as we use them a lot on our fine adjusting screws.

.75x40, .25x80 & 100 etc.

The link I gave above has a calculator for UNS threads which seems pretty accurate from the time we verified it.

My concern is if I spec them as .047-90 (or 96) UNS will this just confuse the vendor. Also if the standard taps are for a class 3 then I'd probably want to specify class 3.

One thought was to spec as UNS with #00 in brackets for reference but I'm still not sure about even putting UNS in this case.

KENAT, probably the least qualified checker you'll ever meet...