Anyone know where to find a 1/8-28 NPT tap?


  #1  
Old 06-02-03, 08:14 PM
MikeVB
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Anyone know where to find a 1/8-28 NPT tap?

I have a compressor with a 1/8-28 NPT fitting and I need to find a way to convert it to fit into a standard fitting such as a 1/8-27 NPT or a 1/4" NPT. Any idea who sells one of these?

Thanks

Mike
 
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Old 06-03-03, 04:13 AM
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Have you tried www.grainger.com ?
 
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Old 06-03-03, 05:13 AM
MikeVB
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Originally posted by mattison
Have you tried www.grainger.com ?
Yes I have and they don't have one.

Mike
 
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Old 06-03-03, 09:48 AM
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You may want to post this in the tool section. Those guys can find anything I'll bet.
 
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Old 06-03-03, 12:24 PM
T
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1/8-28??? How did you determine that it was that particular thread size? I have never heard of it myself. I would think that 1/8-27 would engage o.k. anyway because you wouldn't normally have a full inch of engagement. Over an inch your only talking about an extra thread.

If it is an issue, pickup a 1/8-27 tap and chase the thread, just to be sure and add a little teflon paste to the tape.
 
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Old 06-03-03, 01:15 PM
J
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Where was the compressor made. Could it be metric. There is such a thing as 1/8 - 28. It is listed on my chart under the British & ISO pipe sizes.
 
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Old 06-03-03, 02:37 PM
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Walk right into a major auto parts store such as a NAPA. They carry almost all available taps.
 
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Old 06-03-03, 05:01 PM
MikeVB
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Originally posted by toni1595
1/8-28??? How did you determine that it was that particular thread size? I have never heard of it myself. I would think that 1/8-27 would engage o.k.
I determined it was 1/8-28 NPT because it is the same diameter roughly as a 1/8-27 NPT fitting but a thread pitch gauge shows it as 28 TPI perfectly. A 1/8-27 fitting engages the fitting but only for about a half turn or so.

Mike
 

Last edited by MikeVB; 06-03-03 at 05:18 PM.
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Old 06-03-03, 05:05 PM
MikeVB
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Originally posted by joed
Where was the compressor made. Could it be metric. There is such a thing as 1/8 - 28. It is listed on my chart under the British & ISO pipe sizes.
Joed,

This compressor was made in Denmark and according to their web site the hose coming out of the compressor that I am talking about is 1/8 and not metric. Their web site does not say the thread pitch though.

I thought it might be a 1/8-28 BSP as you stated, but the British 1/8-28 has a 55 degree thread pitch instead of the 60 degree we use. If it was 55 degrees it would look funny with a 60 degree thread pitch gauge on the threads. The 28 TPI gauge fits on it perfectly and the angle of the threads and the gauge look like a match which would make it 60 degrees. I am taking a fitting to work tomorrow to have the machinist look at it.

Mike
 
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Old 06-03-03, 05:16 PM
MikeVB
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Originally posted by mattison
You may want to post this in the tool section. Those guys can find anything I'll bet.
Thanks Mattison.

I forgot this was the electrical forum. lol

I saved it in my bookmarks but failed to go to the starting page URL to save it.

Thanks again

Mike
 
  #11  
Old 06-03-03, 05:25 PM
J
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Are you sure it is not metric. My thread guages 0.9mm matches 28tpi.
 
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Old 06-03-03, 05:36 PM
MikeVB
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Originally posted by joed
Are you sure it is not metric. My thread guages 0.9mm matches 28tpi.
Joed,

I noticed that last night myself. I am not positive that it is a SAE size and not metric. I am going to call the manufacturer tomorrow and see if I can find out.

Thanks

Mike
 
  #13  
Old 06-03-03, 05:59 PM
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Yes, there is a 1/8-28 thread. I had to look it up for myself. It is a B.S.P. thread. I had never ran across it in my years of dealing with the threading industry. I guess you can learn something everyday.

But, in reality, I feel that in this case you could chase out this thread with a 1/8-27 tap and would not have a problem. Especially where you are only talking about a pitch difference of .0013".

You may be able to get a machine shop to turn you one out for a small fee, if they have the die available. I am a little surprised that the vendor don't have an adapter available to convert the thread to N.P.T. anyway....... Good for business and all!!
 
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Old 06-03-03, 07:25 PM
MGJ
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thread question

I work with both NPT and BSP standards daily(machinist).If I were you I'd run a 1/4-27 tap into hole then teflon tape(two wraps) fitting.Put grease on tap to catch metal chips.
 
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Old 06-03-03, 09:03 PM
MikeVB
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Re: thread question

Originally posted by MGJ
I work with both NPT and BSP standards daily(machinist).If I were you I'd run a 1/4-27 tap into hole then teflon tape(two wraps) fitting.Put grease on tap to catch metal chips.
1/4-27? 1/4 NPT threads are 18 TPI last time I looked. I thought you were a machinist? Just kidding with you MGJ. I know you meant to say 1/8-27 my friend.

Thanks for the tips. I have a fitting here that I believe is stainless and it has a male fitting and two female threaded openings on it. I think I will put one female fitting on the compressor, tap the other female fitting to 1/8-27 NPT and plug it and use a die on the male end to make it 1/8-27 also to fit whatever fitting I need to convert it from a 1/8 to the size of the braided hose I buy.

Do you see any problems with tapping stainless over brass? Will it still work alright going over the existing threads?

Thanks

Mike
 
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Old 06-03-03, 10:36 PM
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if you never care about getting it apart again locktite works great for mismatched stuff.
 
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Old 06-04-03, 05:11 PM
MikeVB
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Re: thread question

Originally posted by MGJ
I work with both NPT and BSP standards daily(machinist).If I were you I'd run a 1/4-27 tap into hole then teflon tape(two wraps) fitting.Put grease on tap to catch metal chips.
MGJ,

I took the fitting to work today and had our machinist look at it.
He said it is metric and is not pipe threads. He said it is a 9.5 x .9 M according to the measurements.

Mike
 
 

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