Making a screw thread?

[Filament]

I need to put a screw thread onto a silver pipe I have made and wondered if anyone can give some advice on this.

If I cut the 20mm width silver pipe in half, tap one piece and die the other with the appropriate tap and die would they then screw together? Is it as simple as that? The silver pipe has a wall of 1.5mm

It might be a daft question, but don't want to ruin a piece of silver pipe unnecessarily. I suppose I could try it with copper pipe first. I have never used a tap and die set.

Thanks in advance.

Filament

[Gemma]

Hello Filament and to the forum.

I've never used a tap and die set on silver but have on steel when I was in metalworking at school!
As far as I remember (was a few years ago now) we used the taps with a wrench down the inside of the tubes and dies on the outside of rods. We had to use oil to help with the cutting and lots of small clockwise then back anticlockwise movements rather than just twisting it. Half a turn at a time I think...
Oh and very important to keep it pefectly straight

Well thats what I remember from school but I'm sure someone will have more info on working with silver. There's some very clever folks on here (and v. friendly too )

[Filament]

Hello Filament and to the forum.

I've never used a tap and die set on silver but have on steel when I was in metalworking at school!
As far as I remember (was a few years ago now) we used the taps with a wrench down the inside of the tubes and dies on the outside of rods. We had to use oil to help with the cutting and lots of small clockwise then back anticlockwise movements rather than just twisting it. Half a turn at a time I think...
Oh and very important to keep it pefectly straight

Well thats what I remember from school but I'm sure someone will have more info on working with silver. There's some very clever folks on here (and v. friendly too )

Hi Gemma,
Thanks for the welcome and the answer to my question.

Do you think it would be correct to use the same size pipe for the inside and outside screw thread? Is the tap and die going to remove enough metal for them to fit together? or am I to use different size pipes? Its been puzzling my head for days.

[Gemma]

I'm afraid my memory doesn't stretch to that technical detail! I was only 13 so the metalworking teacher probably just gave us the right sized stuff!
The outside screw thread would have to be cut from thick walled tube or solid rod though as otherwise the screw thread would slice through the tube walls.
Hope someone else can help

[Filament]

I'm afraid my memory doesn't stretch to that technical detail! I was only 13 so the metalworking teacher probably just gave us the right sized stuff!
The outside screw thread would have to be cut from thick walled tube or solid rod though as otherwise the screw thread would slice through the tube walls.
Hope someone else can help

I hope 1.5mm thick tube is sufficient.

I vaguely remember doing this at school too, but I had the same. I was given the right size stuff in the first place. Didn't have to think about it really. But that was a long time ago.

I'm going to try it with some copper plumbers piping I think. Can't harm.

Thanks again.

[geti-titanium]

If I cut the 20mm width silver pipe in half, tap one piece and die the other with the appropriate tap and die would they then screw together? Is it as simple as that? The silver pipe has a wall of 1.5mm

No they won't - if you thread the inside of the tube then the outside of the tube would need to be small enough to screw inside it. By the time you have sized the die small enough for it to cut and screw into the tube the thread will be practically breaking off.

Imagine a 10mm bolt - the nut would need to be tapped with a hole diameter of around 8.5mm.

[Filament]

No they won't - if you thread the inside of the tube then the outside of the tube would need to be small enough to screw inside it. By the time you have sized the die small enough for it to cut and screw into the tube the thread will be practically breaking off.

Imagine a 10mm bolt - the nut would need to be tapped with a hole diameter of around 8.5mm.

I was worried that this might be the case but without having the experience was not so sure.

There must be a method for working out the diameters of pipe needed to do this. I suppose I will need to know the depth of cut the tap and die are also going to make to work it out properly.

[geti-titanium]

this may confuse you even more but it might have the information you require:

TAP DRILL SIZES FOR UNIVERSAL AND M-PROFILE SCREW THREADS

[ben b]

can you let us know how you get on with the copper pipe? it would be interesting to read.
To be honest, this one is making my head hurt!
I'd have thought with a 1.5mm wall, it should be doable, as i have seen items with flush surfaces (same tube thickness) screwed together like this, but i guess it all depends on wall thickness?
You could use a coupler, which would mean just soldering an inside collar inside the two ends where the threads going to go, to thicken the walls.
Im guessing it would be ok to dig into the tube wall by half its thickness, so your thread would be 0.75mm deep????

Let us know how you get on in practice, because the theory's certainly head doing!

[Filament]

this may confuse you even more but it might have the information you require

Not too confusing, but the sizes aren't large enough. I'm looking for M22 sizes.

Thanks for your help though.