Thread: Box for Dies

Excuse my ignorance Vann, but what are conduit dies and how do the differ from, pipe dies or standard thread dies?

Originally Posted by DSEL74

Excuse my ignorance Vann, but what are conduit dies and how do the differ from, pipe dies or standard thread dies?

Hi DSEL.

British Standard Conduit threads are Whitworth threads, as used on the old steel electrical conduit found in old buildings. My first house was built ~1926, and in the ceiling all the lighting wiring was in steel conduit. Just individual cloth coated conductors (which I had replaced with modern conduit wires - retaining the steel conduits) from the days before rubber insulation and TPS. I thought it worth retaining because there's no way the rats were going to eat through the conduit - although it would be prohibitively expensive to install new (if you could find a sparkie who knew how to ).

The wiring between switchgear and motor on my 1928 bandsaw was in modern (bright orange) PVC conduit, and I want to replace it with steel conduit at some point - so I was keeping an eye out and spotted these dies. I'll run the wires in 5/8" or 3/4" conduit.

BS Conduit is 18tpi for 5/8" and 16 tpi for 3/4" conduit, vrs 14tpi for BS Pipe threads and 11 & 10 tpi respectively for BSW threads (although that's not an accurate comparison as BSP threads use the bore for nominal size, whereas BSC & BSW use external diameter - I think).

So I guess the answer to your question is: higher thread count.

Cheers, Vann.

Thanks for the education I'd never heard of conduit thread before. I'm planning to run the Denbigh wiring in copper gas pipe as conduit. The wires are fully insulated of course.


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Nice work on the box.
I hope you have thought of perhaps some sort of handles as there will be a bit of weight, particularly if you get taps as well. Perhaps a couple of rebated finger grips on the side would be sufficient?

Incidentally, shouldn't a "box for dies" be called a coffin?

Vann, unless you have a stash, you won't get imperial conduit. The metric equivalents are not compatible with the old imperial sizes.
I used to carry an assortment of adapters for connecting conduit to old equipment that was threaded imperial.
And yes, conduit is measured ext diameter rather than NB. Unless you go above 80mm then it is measured internal because the larger diameter conduits come in different wall thicknesses.

Thanks for the education I'd never heard of conduit thread before. I'm planning to run the Denbigh wiring in copper gas pipe as conduit. The wires are fully insulated of course.

I'd like to see photos of that after you've finished DSEL74. It sounds similar to what I'd like to do for a couple of my old machines.

Stewie

Originally Posted by NCArcher

Vann, unless you have a stash, you won't get imperial conduit. The metric equivalents are not compatible with the old imperial sizes...

That was to be the next step - find out what OD various tube/pipe comes in, to see if there's a suitable size. I grabbed the dies for $15 without doing the research beforehand .

I may have to watch for demolition cast-offs, or go back to plan 'A' and use copper pipe.

Cheers, Vann.

Nine likes/thanks - wow, thanks guys, I'm honoured.

I made up a frame for the dies, to go into the box...

aDies20.jpg

...and a lid (from an off-cut of thin ply)...

aDies21.jpg aDies22.jpg aDies23.jpg

...and there's a large-ish bag of silca in there, to keep rust at bay.

Originally Posted by Handyjack

...I hope you have thought of perhaps some sort of handles as there will be a bit of weight, particularly if you get taps as well. Perhaps a couple of rebated finger grips on the side would be sufficient?

I still want to rout some hand grips into the ends (the sides, at 13mm thick, are a bit thin).

Cheers, Vann.

Originally Posted by NCArcher

Vann, unless you have a stash, you won't get imperial conduit. The metric equivalents are not compatible with the old imperial sizes.
...

Originally Posted by Vann

That was to be the next step - find out what OD various tube/pipe comes in, to see if there's a suitable size...

This morning I ordered a 5.5m length of 16 OD x 1.6mm WT ERW steel tube (most tube I looked at is nominally 17.3mm OD). It will be interesting to see how good/bad the manufacturing tolerances are - and how blunt the dies are - but I'm hoping to be able to cut a 5/8" BS Conduit thread...

Cheers, Vann.

Vann, will the weld on the ERW be OK for die cutting? Or maybe all electrical conduit is ERW? I don't think water pipe is welded, so die cutting that should be OK.

Graham.

I just had a look here and they have a full range of imperial size tube. I think tube is OD, pipe is ID?
I'm assuming ERW means welded. Conduit needs to be smooth bored to allow cables to be pulled through without damage.
The tube in the link lists conduit as a use and looks smooth.
Use plenty of cutting fluid

This is the product I've ordered.

Fletcher Steel cat.png

It specifically states 16mm is the OD. If the weld is likely to be too hard for the dies, should I heat it to red hot and let it cool before attempting to cut threads - and should I be asking this on the sister (metalworking) forum?

Cheers, Vann.

The weld in ERW tends to be pretty scungy as in full of carbon and impurities, but the real hard bead is on the inside, the outside is rolled smooth. I don't think tempering it will soften it any further than how it comes. The weld bead on the inside does file off, so it isn't too hard. You'll just have to try it with the dies you have I guess.

Graham.