Thread Size of Air Couplers (tapping)

Anyone know of the tap / thread size for those quick connect air clips?

I did a search for ‘thread and thread size’ in the pump’s forum and didn’t find any results.

Also, anyone know the part number or a source to buy those? I remember a McMaster car thread but can’t find it.

fw

gprent - Lap pump = harbor freight tools pump

I just ordered this week and they arrived the next day.

Hey thanks for the quick reply!

Super handy info.

Appreciate it

They come in more than one size. Measure across the threads to get a rough number and then compare it to a chart. The nominal diameter, such as 1/8”, is the inside diameter of a schedule 40 pipe. So what you measure will be much larger then the name it bears.
They’re National Pipe Thread (NPT). The ones I have are 1/8” NPT.
Then once you have that, refer to a chart for the drill size for the tap.

I’m a snob for high quality taps, but if all you’re doing is plastic the cheap ones from the hardware store will work just fine.

I put a parts list when I have posted about the cylinder I made. So if you search from my posts, it should come up.

hey thanks for the response Phil210

I was just looking at my hardware store tap set, and it seems I can’t find any that fit one of my old manufactured cylinders.
It appears to my eye that even the Fine thread tap (NF vs NC, fine vs coarse) is still too coarse for the three on the air coupler. Does that make sense?

[ EDIT: I found the 1/8th” 27 NPT in a seperate area of the tap kit. That matches the 27” threads per inch NPT on the McMaster Car link earlier.
That’s great! Thanks to both of you guys for giving me in the info I need. ]

here’s a screen grab:

Attached are images of the tap and drill size for anyone looking.

Thanks again for the help!

FirstWish,

The drill should be a letter R drill (.339”).
I am sure you already know but… pipe taps (1/8-27 NPT) are tapered. So if you don’t have a gage you are tapping about 1/2 to 2/3 the length of the tap. You don’t want to go too deep because the threads won’t seal properly.
Only go half way to start and then slowly go further to get the correct depth.
Ballpark/for reference when you put in the fitting the threads should engage/be snug with about 2-1/2 to 3 threads from the end of the fitting.

Just noticed, the fitting does seal on the o’ring so you tapping a bit deeper so the o’ring engages.

Sorry about that…

Hey Mike,
You’re on some next level tapping!
I’ll have to do a little research to understand.

I’m slow at this :)

There is a standard for pneumatic connectors. This particular one in these we are using is G 1/8 .

The conservative method of pipe tapping:
Run the tap in so the end of the tap is flush to just past the end of the hole.
This will be short but expected, now insert the fitting. Only one or two threads will go and then it should get tight.
You now have a visual reference for how much deeper you need to tap the hole.

Take your time and you will be fine.

For the male 1/2 of the fittings I think they are using as mentioned, pipe thread measures so I’d guess that you measure the dia. of the hole of the fitting. inside and outside, and go to the engineering handbook to find the nominal decimal value related to the pipe or street size associated to it. PIA that is perpetuated by the trades to keep us guessing and also to keep SAE steel fittings out . I ordered some of those from McMaster-Carr last week $1.61 each and used the decimal od’s and id’s that the website offered on it’s engineering ref. page and still got a fitting that would be appropriate only for a 1/2 inch id hole. That pt. no. was 5012K71. Don’t get that one. I “think” these use a 1/8 ln. (coupling end) pipe thread sizing and a 1/4” barbed hose end that is for 1/8 id hose on our cylinders, but I’m a little slo’ on the gidyyup, after the mis-ordering those numbers. Not much money really until you want the valved shut off female fittings that u guys above are tap ciphering. Those are rich. Later

I hope this helps a bit

The easy way to identify a pipe thread is that they’re tapered.

It’s unlikely that something other than a pipe thread would be used for this kind of application. 1/16 and 1/8 NPT both use 27tpi threads. I’ve never seen a 1/16NPT tap used anywhere; most materials aren’t strong enough for something that small to get torqued down the way pipe threads do.

I’d bet dollars for donuts it’s 1/8 NPT …