Thread: 3/4 inch pipe threading

I did a quickish search and i think Irwin brand make or sell them (the die's), as they're used for plumbing generally, try a plumber's supply, or failing that get your pipes already threaded new, or 2nd hand from housing demolishers. Ridgid brand also does one although it may need a special wrench.

How much were the fittings at supercheap? I was looking for them in brisbane and they don't stock them up here. I know carbatec does them quite cheap.

Neal.

G'day Tiger,

I have 3/4" dies and you're welcome to drop in with your gal pipe to cut them. I'm in Kilsyth.

Hi Tiger,

Have a good high energy breakfast before you head over to thread that pipe! It's not work for the faint hearted.

Cheers Old Pete

Thanks, Thompy and Waldo.
Thompy, bought mine from Super Cheap Auto about a year or so again, but even down here not all stores carry them. They're ok but I find that the spring gets stuck and so the clamp needs a bit of a whack so that it moves along the pipe.
Waldo, might just take you up on your offer however I was hoping to get the job done pretty soon, if not I'll get in touch in with you.

Originally Posted by Tiger

if not I'll get in touch in with you.

Originally Posted by old pete

Hi Tiger,

Have a good high energy breakfast before you head over to thread that pipe! It's not work for the faint hearted.

Cheers Old Pete

That's pretty funny because I can feel exactly what you are saying right now.

I spent half a day yesterday cutting and threading pieces of 1/2" pipe for a 12m long plumbed compressed air line in my new shed.

I have a set of old school 2" square BSP dies and die holder inherited from FIL tool kit. Unfortunately the die holder (which is much nicer to use than a regular die holder since it has a guide to hold the die square to the pipe) had no handles (these are made from 3/4" pipe) so the first thing I was going to have to do was cut two 450 mm lengths of 3/4" and put the 3/4" BSP threads on the ends of these.

Then it dawned on me that it was not going to be easy to cut a thread without a handle. Fortunately the length of scrap 3/4" pipe I was cutting the handles from already had a (rusty) thread on one end so I had a sort of premade handle I could work with and used that to make another 3/4" threaded handle.

Then I used both handles to start on the 1/2" threads. I only turned 9 threads, but this morning I have sore shoulders and arms. Using Trefolex cutting lube helped quite a bit.

Originally Posted by old pete

Hi Tiger,

Have a good high energy breakfast before you head over to thread that pipe! It's not work for the faint hearted.

Cheers Old Pete

Pete, I put some threads on years ago on pipe and it was hard work, it should be easier now that I've matured a bit, I hope.

McJing here in Sydney sell both pre-threaded pipe and 3/4 (+1/2) inch threading gismo's - and for a lot less thatn $85. No idea what the postage would be - I go there by train.

Originally Posted by bsrlee

McJing here in Sydney sell both pre-threaded pipe and 3/4 (+1/2) inch threading gismo's - and for a lot less thatn $85. No idea what the postage would be - I go there by train.

On their wesbite, Mcjing don't have a 3/4" BSP
They have an 3/4 NPTF which is $38.

My understanding is that they will fit each other but they might not seal properly without an extra turn or two of teflon tape.

On their wesbite, Mcjing don't have a 3/4" BSP
They have an 3/4 NPTF which is $38.

they are the same thing

Hi Tiger,
Why not try a Older Plumber, most likely Retired or still at it.
I would think he could do that job in a few minutes, for you.
May ask for a fee, but so what, you would have it done.
You say 3/4in.. I'm sure mine is 1in., but I've only had them 30+ years, so they may have changed by now.

Hi Gents,
Looks like you've got the gist between you all,
An old plumber is your best bet, I got mine from a plumbers supply when I worked the trade (plumbing) , otherwise cheap on the net (quality dependant),
when you get the gadgets make sure you buy thread cutting lube ,
old mate was right Trefolex is a good buy.
its not an easy task, make sure the pipe is well secured before threading.

And your well warmed up prior to starting yourself.
Nothing like a good stretch to warm the veins before putting the muscles thru a workout!
Good luck , let us all know how you go.

Originally Posted by specialist

they are the same thing

My BSP 1/2" die cuts a pipe thread that will not even start on a standard 1/2" NP female fitting unless I file a little off the tops of the pipe threads. Even then I only get about 1.5 turns by hand and then I can get another half a turn with a wrench. OTOH my 1/2" NP die cuts pipe threads that easily fit a 1/2" BSP fitting and will turn by hand ~3.5 turns and then I can get another ~1.5 turns with a wrench. It could just be my tap and die set but this suggests to me that the NP is a little smaller than the BSP and when I look up my thread tables, sure enough the BSP OD is 0.007" bigger than the NP OD.

Originally Posted by specialist

they are the same thing

They are NOT the same. BSPT threads have a 55 degree thread angle and rounded crests and roots. NPT threads are 60 degrees with flat roots and truncated crests. They have the same taper and many sizes have the same pitch but that's all.

Yes, you can usually force the two threads together. You can also hammer in screws with the side of a shifter