I've used silver solder to solder to put together non threaded pieces, that seemed straightforward. I just put in some flux a couple of snips of silver solder, heated the whole thing up until the solder melted, and inserted the rod.
With threaded balls/all thread can I just braze them? Like coat the threads with flux, screw in the all thread, heat it up then touch some of the silver solder to it? Will the flux suck the silver solder down into the threads?
Just looking for some pointers before a ruins some perfectly good materials
I think if you got hold of some threaded balls the idea is probably that you could use loctite thread lock instead of silver soldering them to a rod. However, I'd say that is not really a good idea for ball and socket armatures. It's pretty strong stuff, but not designed to work with that sort of pressure. Silver soldering is always better if you have the tools and skills to do that. You should be able to solder them just fine, it just makes the threaded ball/rod a bit pointless. I suppose as you describe it the balls do not have the whole going all the way through? You mention heating the balls up first and then putting the rod in. You might want to try pushing the rod in while heating everything up, that way you avoid the ball going black inside, and if you get the right amount of solder in you know it's all good when you see the solder flowing out at the top, forming a ring around the rod.
As for the threaded rod, seems a bit of a hassle as you cannot push it down. You can touch some solder from the top and if you make sure the ball is hotter then the rod above it it should suck the solder down. Only problem is, you can't see if it has, so sometimes it might look from the outside like it has worked fine, until the bond breaks halfway a shot and you realize the solder hasn't flown through properly!
I solder to threaded rods sometimes, but the hole in the ball isn't threaded. I just treat it like an unthreaded shaft. For 6-32s I'll file down the threads a little - clear is .140", so I'll use .125" hole.