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

 

Have you tried www.grainger.com ?

 

Yes I have and they don't have one.

Mike

 

You may want to post this in the tool section. Those guys can find anything I'll bet.

 

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.

 

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.

 

Walk right into a major auto parts store such as a NAPA. They carry almost all available taps.

 

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

 

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

 

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

 

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

 

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!!

 

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

 

if you never care about getting it apart again locktite works great for mismatched stuff.

 

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