Where can I get this tap?

[Jaepheth]

I'm trying to create an air-tight adapter to attach a psi gauge to a soda bottle lid.

Near as I can tell, the thread on the gauge is about 11/16 long and tapers from 33/64 to 35/64.

It's definitely 18 TPI.

I figured I'd try to find a 17/32 18TPI Tap, but so far no luck.

Does anyone know where I can get the proper tool?

 

[herm0016]

so... its about a 1/4 in npt thread?

if you dont know npt threads, you should not be messing with pressurized vessels. what are you doing?


http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html


http://www.mcmaster.com/#standard-taps/=haoqu9

 

[SyndromeOCZ]

Careful putting to much pressure in them, when they blow.. its very very loud. Your ears ring for a good 5-10 minutes. It takes about 20 seconds before you can hear anything. That is.. if your holding it when it blows.

 

[herm0016]

i have seen soda bottles blow at around 90psi. we have put up to 100 in them though.
used to mess around with bottle rockets.

 

[Jaepheth]

This is the gist of what I'm trying to make:

(100 PSI gauge)

I thought it'd be cute to measure the bottle pressure while making homemade ginger ale/root beer, and I figured it'd be a good beginner project for my lathe.


(nut mislabeled as washer)

 

[herm0016]

hmm. i see. yes, its 1/4 in NPT thread on the gauge. the tap I linked will work.


i work with pressures in fluid and gas up to 10,000 psi all the time. some of our gear is 15k and 20k working pressure.

 

[Jaepheth]

Thanks...

hmmm.... I guess once I have a standard thread on it I can throw a T connection on there and have a combination gauge and safety valve

 

[herm0016]

the brass stuff is generally good for 600psi. So the home depot type stuff should be just fine for you. I use it on my home hydraulic systems that see a few hundred psi with no problems.

 

[Howard]

Don't bother tapping the lid. Use a through-wall connector.

 

[PottedMeat]

1/4 and 1/8 NPT taps are pretty much everywhere and should come with the right tap drill too. ( Home Depot, etc. )

shouldn't take you too long on a lathe

-drill air hole to approx final length with small drill bit in tailstock
-drill 1/4NPT or 1/8NPT to correct tapping depth
-tap NPT
-reduce diameter for thru cap section to some standard size like 10-32
-parting tool or hacksaw to separate
-use die to thread thru cap section

i'd put a gasket on both sides of the lid.

heh if you want a little less work i guess you could get a NPT female brass connector to hose barb and turn the barb part on the lathe

 

[Bartman39]

Don't bother tapping the lid. Use a through-wall connector.

This...:thumbsup: A lot more simple and can be brass for no more pressure than your using... As stated Home Depot or other hardware stores should have everything you need...