Thread Rolling Dies

[Phil PParticipant @philp]

Has anyone got first hand experience of using the miniature thread rolling dies that can had from ebay ?

I have some in 1.2mm 1.4mm & 1.6mm already, but wondered if anyone has any advice on best use etc.

It looks like the dies do not actually roll on these ones, so they just deform the parent metal into a thread.

Thanks

Phil

Edited By Phil P on 13/12/2020 19:33:43

[Phil PParticipant @philp]

[old martParticipant @oldmart]

I have a hand thread roller for extending the threads on certain gauges of bicycle spokes, it uses three axels which are canted at the thread helix angle with little rollers on them.

I haven't seen the ebay ones, you will have to post a link, or the number.

[Phil PParticipant @philp]

Assuming I am allowed to post a link, here you go

https://www.ebay.co.uk/itm/Thread-Rolling-Die-Head-M-1-6-x-0-35-rod-spoke-threading-head/193755884036

Phil

[old martParticipant @oldmart]

It looks similar to my bicycle rolling head, the rollers do roll. I have only used mine to increase the length of an existing threas. The instructions say run the dies along the thread twice. It works well on DT Swiss stainless spokes common on mountain bikes.

[Phil PParticipant @philp]

I used to thread all my own spokes when building wheels for my British motorcycles, but as you say the rollers on those dies are canted over at the thread helix angle.

The roller dies on this one are all parallel and the helix is on the roller itself. The rollers on their axles are pulled into a taper in the body which then keeps them all tightly pushed together in mesh and they cannot roll, the resulting gap in the centre is what determines the finished thread diameter.

What I am uncertain about is the blank diameter required to start off with so I end up with a fully formed thread, I think I need to do some actual experiments and see what happens.

My plan is to use this for making studs for my model mill engine cylinders etc if it works.

Phil

[Pete RimmerParticipant @peterimmer30576]

Posted by Phil P on 13/12/2020 22:02:58:

I used to thread all my own spokes when building wheels for my British motorcycles, but as you say the rollers on those dies are canted over at the thread helix angle.

The roller dies on this one are all parallel and the helix is on the roller itself. The rollers on their axles are pulled into a taper in the body which then keeps them all tightly pushed together in mesh and they cannot roll, the resulting gap in the centre is what determines the finished thread diameter.

What I am uncertain about is the blank diameter required to start off with so I end up with a fully formed thread, I think I need to do some actual experiments and see what happens.

My plan is to use this for making studs for my model mill engine cylinders etc if it works.

Phil

I would start with a blank that has a very shallow taper and sized just under to just over the pitch diameter. Make a map of the blank and hand roll a thread on it, test-fitting a nut until it binds.

[bernard towersParticipant @bernardtowers37738]

Phil have look at ever hardware.com they have chart with blank sizes

[Phil PParticipant @philp]

That is very useful thanks.

The trouble is my dies are for M1.2, M1.4 & M1.6 and the chart starts at M2.0

No worries I will just have to have a guess and maybe do the tapered approach as Pete suggested.

Phil

[Tim StevensParticipant @timstevens64731]

Just a thought – there are thread-forming taps which work in a similar way, pushing metal into the desired shape rather than cutting it away. They have been around for many years so information on relevant hole sizes must be around too. A comparison of starting sizes and finished dimensions should be similar, and would surely offer a starting dimension at least. It seems to me that the amount of distortion of metal caused by a 'forming tap' must be very close to the amount of distortion from a 'rolling die'.

The forming dies I have seen (ie not many) have a cross-section with six flats and a blending radius where they run together, and are hard-chrome plated to offer good wear resistance.

Regards – Tim

[old martParticipant @oldmart]

What a strange way of producing a thread rolling die. The three "rolls" must be syncronised before they are locked, possibly by having a sample threaded rod in place. If you want to turn them to an unworn part, then the syncronisation process has to be repeated. It would be sensible to make a mark on each roll face, pointing inward to know where to index them. As mentioned, an extra length incorporating a lead in taper would be the best way to start a thread. Iwould use an extreme pressure gear oil as lubricant.

Starting with a slightly undersize rod would be best and gradually work up using a tapped hole in a test piece for a gauge. Different alloys vary in ductility, some are not suitable for thread rolling unless hardened and tempered after the threads are produced.

Edited By old mart on 14/12/2020 13:54:10

Edited By old mart on 14/12/2020 13:59:55

[egaParticipant @ega]

Posted by Tim Stevens on 14/12/2020 13:45:36:

Just a thought – there are thread-forming taps which work in a similar way, pushing metal into the desired shape rather than cutting it away. They have been around for many years so information on relevant hole sizes must be around too. A comparison of starting sizes and finished dimensions should be similar, and would surely offer a starting dimension at least. It seems to me that the amount of distortion of metal caused by a 'forming tap' must be very close to the amount of distortion from a 'rolling die'.

The forming dies I have seen (ie not many) have a cross-section with six flats and a blending radius where they run together, and are hard-chrome plated to offer good wear resistance.

Regards – Tim

PS ignore the next two postings, I don't know why that happens. – Tim

Edited By Tim Stevens on 14/12/2020 13:47:25

Did you, as I have done, unthinkingly press the back button? And then post again because the first one seemed not to have gone off?

[Steve CrowParticipant @stevecrow46066]

I've got the very same dies on the way from Russia!

I found this chart that shows diameters down to M1.6.

I suppose you could extrapolate the diameters for the smaller threads from the other sizes.

Sorry about the image quality, it is just about readable.

Steve

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