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Antique Gas Engine Discussion

Drill/tap size for a common ZERK fitting?


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  #1  
Old 12-26-2007, 03:03 AM
DerekC DerekC is offline
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Default Drill/tap size for a common ZERK fitting?

I plan to fabricate a 1/4-inch pipe fitting with capped-end, and install a grease (Zerk) fitting into the cap.

Is the hole-diameter and Tap for a Zerk-fitting a "standard-size," or are there "Special" taps required to create threads to install a common-size (I know there are various sizes out there, but a typical-sized) Zerk fitting?

I plan to use this arrangement to force (any) old grease out of the various lubrication points on my 1924 FM "Z" engine, then re-install the "original" grease-cups. The engine is new to me (as I bought it a month or so back) and I'm not convinced that screwing in the grease cups is purging out the old, stagnant grease (not seeing grease ooze out anywhere.)

So far, as I screw the cups in I'm not seeing any grease emerge. Granted, if there's less grease in the cups after than before, it has to be going somewhere, but I want to try forcing some grease through the joints/bearings/etc with a grease-gun to be sure lube-points are cleaned-out and flowing freely.

Please advise. Thanks.
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  #2  
Old 12-26-2007, 04:10 AM
Ray Freeman Ray Freeman is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

It will be a tapered thread. You just need to decide on the fitting you want and look up a thread chart for the tapping size. I presume in the States 1/8 NPT would be fairly standard.
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Old 12-26-2007, 07:08 AM
Daric J Daric J is offline
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Talking Re: Drill/Tap Size?? for a common ZERK Fitting?

A common size I have used many times is 1-4" 28 thread. use a number 3 tap drill. grease gun pressure works Great for cleaning passages!
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Old 12-26-2007, 08:55 AM
Rick McKay Rick McKay is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Just unscrew the grease cup and get a reducing bushing that fits the hole in the bearing caps, purge the bearings, then put the original cups back on.

Rick
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Old 12-26-2007, 09:27 AM
j dayman j dayman is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Some zerks are 1/4-28 UNF tapered thread, but they fit a straight 1/4-28 tapped hole. Others I've seen lately are metric M6. Easiest way to check is to find a 1/4-28 nut at a hardware store or in your spare parts bin and see if the zerk thread fits it. If so drill #3 as someone suggested and tap 1/4-28. If the 1/4-28 nut doesn't fit easily it might be M6.

If it is M6, you need a 5mm (.200" roughly) tapdrill and an M6 tap.

The link below shows some other styles of thread on zerks made by Alemite. Has all kinds of thread info.

http://www.aircraft-fasteners.com/im...greaseftgs.pdf

Good luck.
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Old 12-26-2007, 10:18 AM
Walt Roys Walt Roys is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

I'm in agreement with Ray. One the most common zirk sizes is th 1/8". Many tap sets have a tapered tap made for that.
Walt
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Old 12-26-2007, 10:42 AM
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Bill Geyer Bill Geyer is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Derek, like was said above the standard grease zerks are 1/4" -28, a very common tap. When you run the tap in only go a few turns. If you run it in too far the tapered threads on the zerk won't hold well. Try it on some scrap material and you'll see what I mean.
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Old 12-26-2007, 10:56 AM
K D Redd K D Redd is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

As others have said the 1/4"X 28 is common. 1/8" pipe tapper is a another common thread for grease zirts.

Kent
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Old 12-26-2007, 11:22 AM
Pat Barrett Pat Barrett is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Since you are using, I assume, a 1/4" NPT nipple and are going to cap it and drill the center of the cap, It would be much easier to get a 1/4" pipe thread alemite, (zerk) and just screw it directly into the hole you are cleaning. The "Alemite" brand part number for it is "1627-B"
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Old 12-26-2007, 12:05 PM
David Tsr David Tsr is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Go to your local plumbing store and purchase a 1/4 to 1/.8 NPT pipe bushing and you should be able to get a 1/8 NPT grease fitting in any automotive parts store that will fit the bushing, if not your grease gun hose or pipe should screw right in the 1/8 to 1/4 bushing direct, not quite as convient as using the grease fitting but will work OK
Dave
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Old 12-26-2007, 01:15 PM
DerekC DerekC is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

WOW!!!

Thanks for all the GREAT suggestions and advice.

I just found/noticed that a previous owner fitted a Zerk in one of the lube-points that feeds the main gear. It hadn't noticed it before as it's tucked inside and toward the bottom of the engine. I wonder if I could remove it and use it in other lube points? Maybe it's a 1/4-inch Zerk? If not, I'll get busy with some of the suggestions all of you provided in this post.

Oh well, Thanks Again for all the Great replies.

DC
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Old 12-27-2007, 02:01 AM
Mark S Mark S is offline
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Default Re: Drill/Tap Size?? for a common ZERK Fitting?

Hi,
I found a rubber tipped grease gun adapter in our local farm store. It screws on the grease gun in place of the zerk fitting adapter normally found on a grease gun.
I've used this rubber tipped adapter with a grease gun filled with Liquid Wrench or 30 wt. oil to flush out the old grease from bearings by removing the grease cups and pressing the rubber tip into the threaded hole or for flushing out the plain drilled oil holes that are found on many pieces of machinery.
Once flushed out they can be oiled or greased as originally intended.

Mark S
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Old 12-27-2007, 10:47 AM
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Default Re: Drill/tap size for a common ZERK fitting?

It used to wear me out at work, explaining to the warehouse folks how a 1/4" zerk could be smaller than a 1/8" one. Whenever they took inventory they would put the 1/8 pipe ones in the 1/4" bin, and vice versa
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Old 12-27-2007, 01:44 PM
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ListerDiesel ListerDiesel is offline
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Default Re: Drill/tap size for a common ZERK fitting?

Probably not going to impact on your choices, but over here in the UK we have 1/8" Gas or BSP (British Standard Pipe) as the standard for grease nipples, which is not the size of the thread, but the size of the internal bore of the pipe.

Thread tables for the common UK stuff are on our website:

http://www.oldengine.org/members/die...bles/Mech1.htm

You'll see that 1/8" Gas is quite large, 0.383" over the threads.

Smaller nipples use the 1/4" BSF thread.

Propshaft universals use the smaller size a lot, but on trucks that used grease nipples, the 1/8" Gas was very common.

Peter
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Old 12-27-2007, 03:03 PM
Daniel Dorece Daniel Dorece is offline
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Default Re: Drill/tap size for a common ZERK fitting?

Quote:
Originally Posted by Bill Geyer View Post
It used to wear me out at work, explaining to the warehouse folks how a 1/4" zerk could be smaller than a 1/8" one. Whenever they took inventory they would put the 1/8 pipe ones in the 1/4" bin, and vice versa

I live in Kenosha Wisconsin where Oscar Zirk the inventor if the zirk fitting lived after he moved from Chicago and we used to farm a piece of property next to his mansion. I met him a couple of times and wasn't too impressed but a man who had been a mechanical engineer in Oscars plant in Chicago used to visit Oscar regularly. I met this man and found that he was probably the real inventor of the Zerk fitting. He told me something about your 1/4-28 Zerks that not many people know. They are actually 1/16-27 TAPERED PIPE THREAD!! Tell that to the guys in the tool crib.
Iron Wolf
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Old 12-27-2007, 05:53 PM
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kerogas kerogas is offline
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Default 1/16-27 Npt

They are tapered a bit , I have installed a few hundred with my thumb and a box end wrench . Tie rods , ball joints, and that sort of thing .
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Old 12-28-2007, 03:01 AM
DerekC DerekC is offline
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Default Re: Drill/tap size for a common ZERK fitting?

Thanks for the "new" replies.

I ended up buying a few 1/4-28 Zerks and a 1/8-to-1/4 inch pipe reducer fitting. Screwed the Zerk into the reducer, reducer into the bearing-fitting-opening(s), then pumped grease through with a grease-gun.

I also removed then cleaned-out all the grease-cups, removed the paint, buffed-off rust/corrosion with a 90-degree-die-grinder and RolLock abrasive pads, then primered/painted (let dry) and filled the Cups with new grease.

I also scraped-out the bearing-fitting openings, as old grease/grit had accumulated.

DC
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Old 12-28-2007, 10:39 AM
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Default Re: Drill/tap size for a common ZERK fitting?

Good info Daniel, no wonder they are so tapered
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Old 12-28-2007, 10:50 AM
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Exclamation Re: Drill/tap size for a common ZERK fitting?

I have taps & several sizes of zerts for the stuff around the place, NOW-- here comes METRIC zerk fittings , so now I have another box with a metric collection of drills taps & new fittings. = its always something
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Old 12-28-2007, 01:14 PM
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Rob Skinner Rob Skinner is offline
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Default Re: Drill/tap size for a common ZERK fitting?

Quote:
Originally Posted by DerekC View Post
I plan to use this arrangement to force (any) old grease out of the various lubrication points on my 1924 FM "Z" engine,
Hi Derek,
On my grease guns, the hose has a 1/8" male pipe thread on it.

What size are your grease cups? If they're 1/8", remove them and screw the grease gun hose right onto the engine. If the grease cups are another size, like 1/4", just get a reducer at the hardware store.

Eliminate the zerk fittings altogether.

Rob
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