What is the technique for soldering two half domes together to make a ball ?

one of them should be pierced in some way so that gases can escape. Then it is just a matter of line them up (I like to hold mine with binding wire so they do not shift.

They can either be stick (wire) soldered, or my personal preference is to sandwich solder chips between the two halves (So obviously I do mine with one on top of the other... not sure how one would do it side by side without great difficulty).

Be sure to remove the binding wire before you pickle. I know this is the most silly point to mention in the entire world but apparently tonight I missed a piece of binding wire on a ring I was working on and turned the whole thing coper coloured.

I made a ball that was half brass, half copper. I formed the two halves and sanded the edges to be soldered to get them flat. I made a nest from some bailing wire and pushed one half into the nest so it would sit flat. I then fluxed the top, and put pallions of solder around the edge and heated the half to melt all the solder and then pickled it. I then put the other half on the nest and then set the first piece on top. Heating with the torch, as the solder melted the two halves came together into one solid ball.

Now that is how I did it. I didn't have an holes at all for gases to escape, even though everything I've read everywhere says that you need one. My mileage varied. [:)]

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Jim

If you don't leave a hole, there is a good chance of explosion/implosion. Not worth the risk!

Cindy

If you get the seam edges good and flat with a big mill *** file
and if you torch dry Battern's flux on all the seam surfaces
and if you join the halves, open them slightly
and slide a single clean sheet solder chip into the seam
and if you heat the bead thoroughly in a circular motion starting at the bottom ...
the two halves will self-center them selves shortly after the solder makes it's way around the seam due to capillary action.

I'm going to have to try that just to see the "self centering" action.
Only works with Battern's flux you say?

I recently did a bead making demo for a local metalsmith group and someone told me that they attended an Andy Cooperman workshop and he soldered beads by putting chips of solder and flux inside bottom dome and heating. According to the attendees the solder flowed up the sides of the bottom dome and into the seam of the two halves. I haven't tried it yet - but it does sound interesting....

QUOTE: Originally posted by cynmarbil If you don't leave a hole, there is a good chance of explosion/implosion. Not worth the risk!

An explosion is defined as the process in which combustion occurs and spreads so rapidly as to create a high pressure. In this case, you don't have a combustion source within the ball, so you aren't going to have an explosion. When you've heated all the air within the ball, it may "burp" and let out some of the expanding air though.

As for an implosion, once the ball gets brazed it is now a sealed ball with high pressure in it and plunging it into cold water could cause enough of a pressure difference that your ball might implode. It's more likely that it will just crumple. (Its kind of like the old science experiment where you take a soda can, put a tablespoon of water in it and heat it until the water boils. Pick up the can with some tongs and plunge it into cold water and the can will crumple.)

You can keep these things from happening by using a vent, using slow cooling of the sphere, or by using thicker metal that can withstand the pressure difference. In my case, I didn't plunge the ball into water after brazing as I wanted the metal as hard as I could keep it, and I was using 20 gauge metal.

I will agree, you need to use caution no matter what way you go.

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Jim

It definitely isn't something that people who are asking how to solder should try.

I've soldered many spheres together without a hole with no event whatsoever. I think the problem with no vent is with subsequent solderings (if any).

Interesting topic...I've learned a lot here that I'll have to remember to try. Thanks!

I have found that using a thin washer of metal to join the two halves makes for an easier join and if the join is made with a contrasting metal such as gold on a silver ball or silver on a copper one looks good as well, but needs a hole somewhere to allow for expansion, had the experience of one imploding without one, so always use one now.If the same metal is used it is just about invisable and gives a secure join.