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size of drill and tap for grease zerk

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souNdguy

12-31-2005 11:36:53

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Anyone got the size of drill and tap for a 'standard' greasezerk? Not the big 1/8 pipe plug sized ones.. the smaller ones.

thanks

Soundguy

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octave

01-01-2006 13:24:40

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

Some talk about NPT National pipe thread
is tapered thread 3/4 per foot grease zerk from 1/8 ,1/4 ,3/8 1/2,ect. all use NPT thread [taper pipe thread] Did I seay 1/4 28 fine bolt thread Zerk & 1/4 NPT Zerk Are not the same. Yes that is correct you have two sizes of 1/4 Zerks One uses 1/4 fine bolt threads the other uses 1/4 Pipe NPT thread
Pipe thread Zerks are in Heave equipment

Retired Machinist

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Tim PloughNman Daley

01-01-2006 07:33:36

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

Happy New Year Sounder Man-

Misconceptions about NPT taps always amaze me. NPT ( National Taper Thread ) American Standard Taper Pipe Thread. Key word is TAPERED. Slope is exactly 3/4" per foot. Tap size refers to orrifice opening of the mating part, not the actual tap major diameter. 1/8 NPT actually has 27 threads per inch, but they don't measure NPT that way. Perhaps that is why a 1/4-28 tap works- for a while - until you screw in the fitting too far and strip out the major diameter. Someone mentioned Interfernce Fit threads- which are NOT tapered Pipe Threads. They are straight threads used on manifold studs but are similar to NPT threads because they are meant to be screwed in once and allow the thread to "crush" itself over and form a seal. HTH

Tim Daley (MI)
*8N15513*

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soundguy

01-02-2006 04:47:06

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Re: size of drill and tap for grease zerk in reply to Tim PloughNman Daley, 01-01-2006 07:33:36

Wow.. lotsa info here... kinda boggeling.

So.. What do you sugest I use for a tap for my zerk issue? 14-28 NF ? Or? light hand on 1/4 npt?

Soundguy

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Tim PloughNman Daley

01-03-2006 16:35:58

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Re: size of drill and tap for grease zerk in reply to soundguy, 01-02-2006 04:47:06

Hey Sounder-
Pipe thread sizes refer to the INSIDE DIAMETER of the pipe it fits. Example- 1/8-27 NPT (National Pipe Tapered Thread). The 1/8 refers to the diameter of the inside of the pipe it would connect or cause flow to. For the 1/8-NPT, machinist chart shows Letter R drill [.339 decimal equivalent] Look at part or Zerk to be threaded into the hole you want to tap. Mic or caliper the smallest end by the opening. Is it a little larger than your drill size? If not you have the wrong tap size. The tap is tapered by 1/16" per inch or 3/4" per foot. It is meant to seal after a few turns by hand. If you keep turning tap into part, you will eventually strip it out by enlarging the hole size to the major diameter of the pipe tap. Re-drilling out to retap same size doesn't make sense-your hole size should already be there. Unless you have a 1/16-NPT Zerk. 1/4-28 UNF (Unified National Fine)is a straight thread as I said. 1/8-NPT has 27 TPI (threads per inch) Somehow it seems you will cross thread something and the mating part (Zerk) won't thread in. The OD of the largest part of a 1/8-NPT male end will mic close to 3/8". Seems your Zerk is smaller than that. You could open up smaller hole to next size up-i.e. 1/16-NPT to 1/8-NPT... HTH

Tim Daley (MI)
*8N15513*

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soundguy

01-04-2006 04:29:38

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Re: size of drill and tap for grease zerk in reply to Tim PloughNman Daley, 01-03-2006 16:35:58

Got it, thanks.. I found a real 'zerk' tool that had a thread chase on it.. worked like a charm.. zerk is in nice and tight.

Soundguy

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Tim PloughNman Daley

01-04-2006 04:58:39

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Re: size of drill and tap for grease zerk in reply to soundguy, 01-04-2006 04:29:38

Here's a link to help clarify taper pipe threads and Zerk specs. There is a 1/4-28 taper thread and also there is a straight pipe thread. Didn't mean to get to confusing...

Tim

Zerk Fitting Info

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Tim PloughNman Daley

01-01-2006 07:52:27

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Re: size of drill and tap for grease zerk in reply to Tim PloughNman Daley, 01-01-2006 07:33:36

...correction:

NPT ( National Pipe Taper[Thread] )

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souNdguy

12-31-2005 22:11:03

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

Thanks guys. i just got my tools out and have them setup and ready for ?monday? night when i will drill out and retap that zerk. After removing some surface rust and gunk from my tap set, I did notice than most of them specify drill bit size.. nice to know.

thanks for all the info.

Soundguy

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octave

12-31-2005 16:50:19

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

1/4 28 thread 7/32 drill bit will do it 1/4 28 is same as 1/4 fine bolt thread means 28 threads per inch
you can get the zerks at auto part stores ask for 1/4 28 NPT [national pipe thread] is used on larger zerk & button head fittings used mosely in industery

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Hobo,NC

12-31-2005 14:42:44

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

7/32 drill bit and a 1/4" find thread tap I have done a bunch of'em with no problem, you need sum interference fit werks great.

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Dell (WA)

12-31-2005 14:15:50

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

Sounder..... ....page 2273 of www.McMaster-Carr online catalog is a full page of tap drill sizes and drill sizes chart. machine screw, SAE fine thread, USS coarse thread, Metric threads. numerical drills, letter drills, wire-gauge drills and metric drills and decimal equivalents. I printed off a copy and refer to it all the time.

For a 1/4-28 (fine) use #3 wire drill (0.2130") For a 6mm-1mm thread, use #10 wire drill (0.1935) or 5mm drill (0.1968") 6mm = 0.2362"

Most likely, yer ferrin spredder is METRIC..... ..Dell

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TIMW(PA)

12-31-2005 14:08:30

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

Drill a 7/32" hole for 1/4-28 zerk fitting. The Zerk thread itself is NPT. I could not find any info from any of my industrial supply books for a 1/4-28 NPT tap. All the scources I found said to use the 1/4-28 NF tap. Thats why DAN die was cutting the zerk when he tried it in the 1/4-28 NF tap. Probably designed that way to help it seal and prevent vibrational loosening....HTH Tim

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old 9

12-31-2005 12:58:15

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

I have used a 1/4 by 28 before and worked ok. May not be perfect? Happy New Year!!!!

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Dan

12-31-2005 12:01:05

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Re: size of drill and tap for grease zerk in reply to souNdguy, 12-31-2005 11:36:53

I just ran a standard zerk through a die and it used a 7mm X 1.00 die. This is for the standard zerk you would use like on a spindle housing. Can't help you with the drill bit size.

HTH,
Dan

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Ken N Tx

12-31-2005 12:13:50

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Re: size of drill and tap for grease zerk in reply to Dan, 12-31-2005 12:01:05

Memory wants me to say 1/4 X 20...I maybe wrong!!

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Dan

12-31-2005 12:24:16

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Re: size of drill and tap for grease zerk in reply to Ken N Tx, 12-31-2005 12:13:50

Using the thread count "feeler" gauges on my tap and die set, the threads are definately a 28 count, and the zerk would not fit into a 1/4" die without cutting into the "body" of the zerk (but the threads would fit). "Maybe" the zerk was a tad off, because I thought it was a 1/4" as well - but it fit smoothly into a 7mm X 1.00 die (shrug)

Dan

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Stickler

01-01-2006 06:13:49

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Re: size of drill and tap for grease zerk in reply to Dan, 12-31-2005 12:24:16

They're usually a special tapered thread made just for grease fittings. Look in McMaster Carr under grease fittings, and there's a whole list of different sizes. At the top of the page it explains what the letters mean. A �-28 would work, it's the fitting that's tapered. All I've used for that size anyhoo.

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