Grease Fitting

Ted in NE-OH · Jul 31, 2013

I have a grease fitting whose thread diameter is about 3/8 in. Is the thread a pipe tread or a straight thread?

Paul from MI · Jul 31, 2013

Most likely 1/8-27 NPT, pipe thread. But grease fittings are available in 5/6-24 NF fine thread, and many other sizes.

Tom vertiz · Jul 31, 2013

Most grease fittings I have seen are straight thread.

Tom vertiz · Jul 31, 2013

As I figured someone was gonna say it could be a pipe thread.

36F30 · Jul 31, 2013

(quoted from post at 18:53:25 07/31/13) As I figured someone was gonna say it could be a pipe thread.

Millions of pipe thread(NPT) grease fittings out there.
Contents of a Lincoln grease fitting kit

Item : Grease Fitting Kit
Type : Fractional Assortment
Thread Size : 1/8" to 1/4"
Number of Pieces : 100
Includes : (20) 1/8" NPT Straight, (40) 1/4" to 28" Straight Short Thread, (10) 1/4" to 28" 45 Degrees Angle Short Thread, (10) 1/8" NPT 65 Degrees Angle, (10) 1/8" NPT 90 Degrees Angle, (10) 1/4" to 28" 90 Degrees Angle Short Thread

Duner Wi · Jul 31, 2013

You did not say what you are working on so don't forget the metrics. 10 MM is about 3/8 inch.

http://www.saeproducts.com/metric-grease-fittings.html

Dick2 · Aug 1, 2013

Go to Harbor Freight and buy a box of SAE serks and a box of Metric zerks and then you are covered to match any zerk that you have to replce.

FBH44 · Aug 1, 2013

Excellent question ; Best I could ever figure out they were pipe thread, so they don"t leak. However, I never could find a pipe thread tap. So, what I have done, is just use a straight thread tap, about the same size, maybe just a schoonch smaller, tap it, and ram "er in there. Not the best way, I"m sure, but it sorta works,

gene bender · Aug 1, 2013

Take the old along to get a new one then see if it goes in a pipe female thread or whether a 3/8 fine thread nut will fit.

Billy NY · Aug 1, 2013

One of the handiest and most inexpensive tools I have in my tool box is a thread pitch gauge, just for this purpose, I used to waste a fair amount of time every so often identifying threads, these do help quite a bit.

Leroy · Aug 1, 2013

The standard of the industry was a 1/8" pipe thread that is close to the 3/8" but still a long way away. Then the next standard is a 1/4" by 28 thread fitting and that ia slso what is used in the angle 1/8" pipe thread fittings and the 1/8" pipe thread there is the straight and 3 different angle fittings, the 1/4" is only as a straighet fitting and then not very popular but used on some implements is a 5/16" drive in fitting that has gripper rings around to hold it in that might be confused with threads. Then there is the metric fittings that are newer than anything I have worked on so know nothing about those but that 1/8" pipe thread tap should be easy to get and for that size it would be an 11/32" drill bit. The 1/8" pipe thread fitting will screw into the gun where the pipe or hose is.

Leroy · Aug 1, 2013

Forgot to say there was also a 1/4" pipe thread fitting but not common. The 1/8" fitting takes a 7/16" wrench and I buy thost fittings 30 or more at a time as I use that many. The 1/4" straight thread fitting takes a 5/16" wrench.

showcrop · Aug 1, 2013

I have changed many in my fifty years of wrenching and I have yet to find one that was approx. 3/8 that the 1/8 npt would not thread smoothly into. Yes, I have worked on a lot of metric but they always had smaller ones.

da.bees · Aug 1, 2013

Look close at fittings and notice nany of the threads are tapered. I don't think you will find an application for tapered sae but all npt are tapered. There simply is not enough depth to easily check.

Grease Fitting

Ted in NE-OH

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Paul from MI

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Tom vertiz

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Tom vertiz

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36F30

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Duner Wi

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Dick2

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FBH44

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gene bender

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Billy NY

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Leroy

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Leroy

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showcrop

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da.bees

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