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1/4-28 grease zerk tap?
- Thread starter Batmanacw
- Start date
There is a good chance its 1/4-28 like a standard grease fitting....just like my thread pitch gauge says.
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- Sep 24, 2020
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- 1,907
just pointing out that if it was npt, it would be 18 tpi.........
And over a half inch diameter
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- Apr 29, 2019
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- 2,063
IF it was 1/16 NPT-27 it would be tapered and 0.313 major dia at the big end and the minor dia at the small end would be 0.242. This would be a rare animal.
A standard 1/4-28 is the second most common Zerk size sold.
A standard 1/4-28 is the second most common Zerk size sold.
I always use a std 1/4-28 tap the grease fitting will tighten down on the hex most of the time
Probably not. If you have a "normal" 1/4-28 grease fitting, it's taper is designed to wedge it's self (and seal with) a normal, standard, straight threaded 1/4-28 hole. Tapered thread into a straight hole. How wrong is that? They work better than you'd think.
You've gotta watch out depending on WHERE you got the fittings, and WHAT TYPE they are.... There's zillions of ways they're made. But if you didn't order anything special or fancy, it's probably one of a common few.
1/4-28 straight (normal 1/4-28 tap) and it "might" leak grease around the thread. Most people get good at stopping the tap early so the bottom thread wedges into the first thread that's not fully formed. But they're meant for straight holes with no shenanigans like that.
1/4-28 tapered threads, which as I said, are designed to wedge into 1/4-28 straight holes, with none of the shenanigans above.
1/8NPT threads, which work with a 1/8NPT tapped hole.
6mm, 8mm, and 10mm straight threads, which work nicely with straight tapped holes. Typically sealing more predictably than the imperial counterparts, but not totally infallible. Tapping short can apply here too.
And the "drive" type... Pick a measurement system and then pick a size. You make a precision hole, and use a special "driver" to hammer them in. Essentially a press fit in lieu of threads.
Again, there's THOUSANDS out there, but unless you're ordering "special stuff", that short list will have you covered.
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- Sep 24, 2020
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- 1,907
McMaster-Carr
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The taper is on the fitting only, female threads are straight UNF.
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- Jan 4, 2021
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- 912
1/4 NPT would not be 1/4" wide. NPT is measured on ID, not OD.