silver solder/braze query

savarin

savarin

Active User
H-M Supporter Gold Member
I have 3 strips of brass to solder/braze to every other side of a hexagonal nut.
The nut is 19mm across flats and the strips are 25mm wide.
The nut must be at 90' to the strips and all three strips must sit flat so there must be no movement during the process.
I am considering using 2 small M3 screws at the end of the strips so they bolt onto the hex getting it all flat and tight then silver soldering the whole assembly.
If I were using soft solder I would pre tin the parts before heating.
Is a similar process possible with silver solder/braze?
Is it even worth while or just rely upon the solder wicking into what would be a tight joint?
 
I have seen parts that were silver soldered together by assembling in a jig to hold position with thin pieces of solder between the pieces (probably a dab of flux also). Heat the whole thing up and voila.
 
savarin said:
I have 3 strips of brass to solder/braze to every other side of a hexagonal nut.
The nut is 19mm across flats and the strips are 25mm wide.
The nut must be at 90' to the strips and all three strips must sit flat so there must be no movement during the process.
Click to expand...

Most hard solders have similar melting points to brass; it's NOT an easy task. Pre-tinning can be done with electroplating,
which in theory will make a surface layer that (because of the plated-on impurity) has lower melting point.
The usual way to do this kind of delicate work is to assemble with flux, and load the whole thing
fixture and all into an oven. Preheat, soak, full heat, cooldown will take a bit of time.

Could one slit the nut to make a pocket for the brass to sit in, and use a hard-ish soft solder? A hand torch
would work, and it's quick, if the parts are secured enough not to move.
 
Another idea that may work in your case is to make a simple clamp from a piece of pipe or tubing that is large enough to fit around the assembly. Tap and drill holes at three equi-distant points around the perimeter of the piece of tube. Use screws through those tapped holes to clamp the pieces to the nut. The hard part here would be getting all of your brass parts to line up properly and get them all tight at the same time.

After that the usual silver soldering steps should work just fine.
 
I'm used to using hard, medium and easy s/s on silver so I could just bite the bullet and perform three consecutive tasks but really wanted the unit done in one go in the hope it would minimise the possible stuff ups.
Pity I dont have an oven large enough to hold the complete unit, its 360mm dia.

BtoVin83 said:
I have seen parts that were silver soldered together by assembling in a jig to hold position with thin pieces of solder between the pieces (probably a dab of flux also). Heat the whole thing up and voila.
Click to expand...

I had thought of hammering out the solder to a very thin ribbon and doing that.
Thanks for the solder paste idea, I've found a local supplier (hey, its in Australia so thats local even if its across the country) of easy silver solder paste so thats the method I will use along with the two screws to hold alignments.
 
An old silversmith's technique to get really thin solder is to knock a few nail holes spaced about an inch apart along the bottom corner of an old baking pan. Put some coils of solder in the pan, bring the torch to bear, and just as the solder hits the melting point draw the pan across a sheet of cold steel. The molten solder runs out the holes and sets in very thin strips on the steel. Lift them off, slice into slivers using shears, and use to set in between the pieces to be joined as you would otherwise. Makes for almost paper-thin solder.

Then again, I just hammer mine out on the anvil. Faster, but not as thin.

-frank
 
You must log in or register to reply here.
Back
Top