How do you bend a tube?

[klevellcaine]

Hello again,

I recently made a baby teething ring necklace using a silver tube, but I had a lot of trouble getting the tube into a true circle. I'd flattened the circle a bit to solder the two ends together, but I was then stumped how to get rid of the 'bump'. Obviously with a piece of wire, you can just hammer it on a round mandrel, but that's not an option with a hollow tube. What's the trick?

Thanks in advance,

Karen

[pearlescence]

Well, plumbers put a spring inside the tube to stop a round pipe squishing when they bend it..can you improvise something similar? I'm sure that there is a more jewellery way to do it, though.

[klevellcaine]

Interesting...

[Goldsmith]

If the tube is a wide diameter with a thin wall, fill it with setters cement, bend it into a slightly smaller circle than required so that the ends overlap, then gently heat the tube and melt the cement out before annealing the whole piece to burn off any remaining cement, finally clean the ends of the tube, align the circle, flux and solder.

James

[CJ57]

Thanks James, I didn't know that either it's a useful thing to know

[enigma]

Ive been wondering this for ages!
Have read other things like put a wire inside or fill with sand but this sounds like a far better idea as I was thinking if the wire was thick enough to prevent the tube kinking it would be next to impossible to remove once bent.

[enigma]

Would this stuff work James?
This is what I have in atm:
http://www.cooksongold.com/Jewellery-Tools/Setter-Pitch-Sticks-Box-Of-10-1---Kg-prcode-999-2383

[Goldsmith]

Would this stuff work James?
This is what I have in atm:
http://www.cooksongold.com/Jewellery-Tools/Setter-Pitch-Sticks-Box-Of-10-1---Kg-prcode-999-2383

Yes Sarah, I have the same stuff, I forgot to add that I would heat up the tube before filing it with the setters cement, this helps the cement fill the tube before it sets.

James

[Ada]

Would this stuff work James?
This is what I have in atm:
http://www.cooksongold.com/Jewellery-Tools/Setter-Pitch-Sticks-Box-Of-10-1---Kg-prcode-999-2383

I see the description includes this advice:

"Any residue can be removed with alcohol."

This conjures up a picture of a glass of wine helping things along :)

[ps_bond]

Vodka will work better, although I tend to use meths for cleaning and drink the vodka.

[enigma]

:rofl: everything is helped by a glass of wine I find!

Thanks James, thats really helpful!

[Dennis]

As usual, the devil is in the detail.

1.To buy setters cement, you have to buy a kilo. I found it too treacherous when used for its real purpose, so having bought it ages ago and only used one stick, I cant remember where I hid it in shame. Most of us now use Polymorph or similar for holding our work.

2. If used as a temporary filler for tubing, It will be very challenging to fill a bangle sized tube with it, presumably in the form of dust or crumbs, before melting it.

3. Finally having bent the tube and melted out some of the goo, it will need a prolonged soak in meths/vodka to remove all residues. Otherwise the smoke generated when soldering could spoil the joint.

One thing I do predict: To avoid damage, the tube will have to be bent around a wooden mandrel by hand until the ends crossover. To get enough purchase to do this you will need two or three cm of excess at each end.

[WitchfordSilver]

I have heard that you can form around copper draw down to the size you want, then bend the rod with the last operation being to use acid to remove the copper from the middle. I also think I've seem people fill it with water and freeze, bend then melt.

[ps_bond]

For higher carat gold, yes - nitric will eat the copper and not do much to the surface.

[Dennis]

I also think I've seen people fill it with water and freeze, bend then melt.

Reminds me of a recipe for the perfect crime. Stab someone with an icicle.

[klevellcaine]

Thanks again, people. I love the water and ice idea - should help to keep the vodka cold too or did I miss the point? :-D

[trialuser]

Or this stuff (http://www.mindsetsonline.co.uk/Catalogue/ProductDetail/fields-metal?productID=a439e2c4-a149-43d1-9460-fc21a6994c1d&catalogueLevelItemID=d8d06267-959e-4e5f-958a-c9a7b5eeb8ad)
A bit expensive though, but reusable.

[MeadMoon]

Oh, I like the look of that, trialuser. Don't have anything to use it on at the moment though.