Zerk fitting thread size?

There are all kinds of thread sizes.

1/4-28 straight, 1/4-28 tapered, 1/16 npt, 1/4 drive-in, 1/4-20, etc

Usually use the 1/4-28 tapered with no leaks in almost all holes that size. Have run into a lot od joints that arent even threaded anymore, just an open hole with not even a plug.


Here is a link with most, but not all fittings.

http://www.saeproducts.com/as_grease_fittings.html
 
Thanks for the link. According to the info, a tapered Zerk goes into a 1/4''-28 UNF-3B straight-threaded hole. And the less popular straight Zerk goes into a 1/4''-28 UNF-2A straight-threaded hole.

Looks like I'll have to get a 3B tap. Why isn't anything easy!
 
Twin_Turbo said:
What does 3B & 2A stand for?
Click to expand...

The number stands for the thread class which designates the "fit" of the threads. I believe a class 3 is a slightly smaller tap that results in a tighter thread fit.

Sorry Gene, I don't think any lawyers had anything to do with this.:amazed:
 
For any I have had to drill and tap, I just used a regular 1/4-28 and never had any probs, but they were just joints, nothing critical.
 
BBShark said:
Twin_Turbo said:
What does 3B & 2A stand for?
Click to expand...

The number stands for the thread class which designates the "fit" of the threads. I believe a class 3 is a slightly smaller tap that results in a tighter thread fit.

Sorry Gene, I don't think any lawyers had anything to do with this.:amazed:
Click to expand...

I never knew there was any difference in that shit, as it's always been handled by a one on one replacement....now to find out there are in fact FIVE type of holes for a freeking ZIRC fitting???

yah GOTTA be kiddin' me....

:bonkers::mad:
 
Yep, class 1,2 and 3 threads. we use them all the time in aviation. Mostly repair stuff, but there are places that spec a specific thread class.

Ive even seen zerks that were like self tapping screws. Handy stuff.
 
TimAT said:
Yep, class 1,2 and 3 threads. we use them all the time in aviation. Mostly repair stuff, but there are places that spec a specific thread class.

Ive even seen zerks that were like self tapping screws. Handy stuff.
Click to expand...

That's what I recall using. The threads were tapered, and cut until seated.
 
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