Interlocking bangles

[bruggen]

I’ve been asked to make three interlocking bangles like a huge Russian wedding ring. I will be using 3.2x1.9mm oval sterling silver wire. The bangle sizer I have is numbered and she wants a No18, this equates to a 65.07mm diameter though it measures 65.4 with a calliper.
My question is what formula do I use to get the right size, as an engineer teaching metal bending we used the formula pi x d+1/2t, with rings I normally use pi x d+t where d is diameter and t is thickness, pi being 3.142, I have assumed that for three interlocking bangles they should be pi multiplied by the diameter plus three thickness’ is this right, I don’t want to mess it up.
Any advice would be much appreciated, I’ve bought enough metal to have two attempts just in case.

[josef1]

I always find it a bit of a mystery trying to work it mathematically. I did it in cad and got the wire length to be 232.7mm thats a 65mm diameter
.

The pink line is the size circle I used the size of wire you specified. I would maybe make it up in 2mm copper wire first to check

[Dennis]

Basically, the three intertwined hoops must pass over the folded hand, and must each be quite a bit larger than a single hoop.

There is no published formula, but if you take Joseph's suggestion and make it in copper first there'll be no disaster, but a starting point for further adjustment, if needed.

When I have done this for a finger, the size of the three rings used was three English sizes bigger than for a single ring. Dennis.

[Ruedeleglise]

Basically, the three intertwined hoops must pass over the folded hand, and must each be quite a bit larger than a single hoop.

There is no published formula, but if you take Joseph's suggestion and make it in copper first there'll be no disaster, but a starting point for further adjustment, if needed.

When I have done this for a finger, the size of the three rings used was three English sizes bigger than for a single ring. Dennis.

Thanks Dennis. Was just about to start on a 3 rings commission
and you have answered my question before I could ask it!
David


Sent from my iPad using Tapatalk

[bruggen]

I always find it a bit of a mystery trying to work it mathematically. I did it in cad and got the wire length to be 232.7mm thats a 65mm diameter
.

The pink line is the size circle I used the size of wire you specified. I would maybe make it up in 2mm copper wire first to check

Wonderful, thank you, there must be a mathematic formula though, I did nearly get the same result as you, my calculation was the diameter of the first bangle plus three times the wire diameter multiplied by 3.142 the number i got was 223.7mm, I have ordered some copper wire and pass it through my roller and try your calculated length and see what size I get, if its then too big I can always reduce the bands. Thank you again, I will let you know what I get.

[bruggen]

Dennis, oh no, if anyone would know I would have bet money and put my faith in you, I have read conflicting descriptions of making three band rings, I think I took your advice on that with the three sizes bigger, there was a different description and that was a multiplicand that ramped up exponentially depending on the number of rings, I can't find the reference now, I have ordered some thicker copper wire and will try to roll it down to more of an oval shape and attempt it as josef1 suggested, as always I thank you.

[Caro]

How weird is that. I've just acquired some bangle dies and am currently obsessed with making bangles!

I was just thinking of making an interlocking 3 band bangle myself yesterday and then this thread appears! Mine would be 60mm internal dimensions (wanders off to find calculator).

Thank you mathematical geniuses!

[bruggen]

How weird is that. I've just acquired some bangle dies and am currently obsessed with making bangles!

I was just thinking of making an interlocking 3 band bangle myself yesterday and then this thread appears! Mine would be 60mm internal dimensions (wanders off to find calculator).

Thank you mathematical geniuses!

I have just bought some 2.5mm copper wire, I plan to roll it down to 1.9mm and hope it goes a little oval too, then put the information and advice to the test plus my own theoretical equation to find out how to end up with the final right diameter . by the way what is a bangle die? what does it look like? or did you mean a mandrel?

[Caro]

I have just bought some 2.5mm copper wire, I plan to roll it down to 1.9mm and hope it goes a little oval too, then put the information and advice to the test plus my own theoretical equation to find out how to end up with the final right diameter . by the way what is a bangle die? what does it look like? or did you mean a mandrel?

This is a bangle die. You use it to make fancy shaped bangles

https://www.cooksongold.com/Jeweller...rcode-999-6876

[Dennis]

Please don't anybody go straight ahead without testing it in copper first. Dennis.