How to thread very short piece of pipe?

[c.p.huntington]

I'm using a very short piece of pipe called a close nipple to attach the check valve to the side of the boiler.
Unfortunately, the shortest nipple I can find is about 3/4" long and that leaves the check valve hanging out
over the middle of the running board instead of up against the boiler. I've tried to make a shorter nipple by
cutting one end off and retreading it. The problem I'm having is that there doesn't appear to be a good way
to hold the nipple while I use the die to tread the cut end. Is there a trick to retread the cut end with out
messing up the threads on the uncut end? The pipe size I'm using is 1/8''. Thanks for any advice you can
give me.

- C. P. Huntington

[LVRR2095]

Can you screw the threaded end into a coupling that you then hold the coupling in a vise or lathe chuck?

Keith

[Bill Shields]

I assume that you are working with some scale copper or brass pipe / tubing.

Description for 1/4" diameter short nipple, made from solid brass stock;

Drill a hole less than 1/8" diameter through the piece you want to thread (do all in lathe). thread one end.

Take a 1/8" hex key, using a dremel, cut off a piece about 1.5" long. grind the end so it is very flat and sharp cornered

use a small arbor press to push the hex key into the piece...like a broach

chuck the key in the lathe to hold piece so you can thread the other end

use a drift to bang the hex key out when you are finished.

If you are doing many of these things (as I have), I actually take the key and do some additional grinding on it to make a proper 'push through' broach so that the key cuts in, then falls out the other end. Once the short nipples have the hex broached through the center, they are easy to hold.

Note: this does not work well with copper tubing

[Fred_V]

How about threading one end and cut it of to the length you want and silver solder it to the valve.

[Bill Shields]

is OK until you need to disassemble in the field...

[RET]

Hi,

Why not just soft solder the nipple to a piece of the proper size rod and then hold the rod in the lathe to thread the pipe? When you are done, sweat the pipe off the rod and clean up the inside a little. Doesn't work too well for production lots (not fast enough) but should work just fine for one or two pieces.

Soft solder works OK for temporary holding of pieces to work on and its easy to solder on and to remove the part when you are finished. I've used it to hold small parts for CNC milling. Works just fine.

Richard Trounce.

[kenrinc]

You don't mention the check valve type, which may have a bearing on how or where it's location eventually ends up. Some checks I've seen don't leave much room based on their physical size. I wanted to be able to do maintenance on the check at a moments notice so I have an angle valve ahead of the check. Anyway, I had to do the same thing in that I needed a small nipple for the boiler. The nipple I made was just 1/8 NTP on the boiler side and 5/16 MTP on the check side. I made it from hex stock with a small bit of hex left in the middle between the two threaded ends so I could use a wrench to get it in the boiler. It also allowed me to hold it in the 3-jaw to complete the nipple. I bought the check and valve assembly based on the measurements I'd made. I had 1/4" of space between boiler shell and boiler jacket which helped. The check valve was provided with a 5/16 MTP union which screwed on the end of the nipple on the check side and the check screws to this (fine thread). Allows easy maintenance and also allowed for a tight install.

$.02

Ken-

[warmstrong1955]

I've repaired threads on hydraulic adapters & pipe nipp's, holding them with a fluted pipe easy-out.

http://www.amazon.com/Ridgid-35680-882- ... B0019MSWVC

Drive it in, chuck the end of the easy out in a vise, and die the threads.
Screw on a coupling, and turn it over, and drive the easy-out back out.

My set is Ridgid. Not sure if anyone else makes that style.



Bill

[rkepler]

I've drilled & tapped an emergency collet for MTP threads to make close nipples. Makes for easy & strong clamping for when the die is cutting that last thread.

[Greg_Lewis]

I've drilled & tapped an emergency collet for MTP threads to make close nipples. Makes for easy & strong clamping for when the die is cutting that last thread.

x2. Works great.

[Bill Shields]

now that is a cool idea!

[cbrew]

I'm using a very short piece of pipe called a close nipple to attach the check valve to the side of the boiler.
Unfortunately, the shortest nipple I can find is about 3/4" long and that leaves the check valve hanging out
over the middle of the running board instead of up against the boiler. I've tried to make a shorter nipple by
cutting one end off and retreading it. The problem I'm having is that there doesn't appear to be a good way
to hold the nipple while I use the die to tread the cut end. Is there a trick to retread the cut end with out
messing up the threads on the uncut end? The pipe size I'm using is 1/8''. Thanks for any advice you can
give me.

- C. P. Huntington

I know others have already suggested some good tips and tricks, but i handled this but "chocking" up on the close nipple. basically, I drilling the hole in the boiler and check valve base a little large then what the 1/8 npt tap called for, this allowed me to run the nipple in deeper, in turn drawing the check right up to the boiler jacket.
depending on the casting of the check, you will most likely need to grind a tap (shortening it)

happy building