Silver Soldering in a Kiln

[Nigel Taylor]

I bought a small kiln and just had to explore some different techniques. This took a few experiments to get right but I think the resultant joint is rather nice (this brass part is roughly 25mm or 1 inch in length)

and a youtube (a bit rough) of me making this silver soldered join

 

[marcros]

nice. my (rather boring) goal is to be able to silver solder by the end of the year.

 

[Nigel Taylor]

nice. my (rather boring) goal is to be able to silver solder by the end of the year.

Hi Marcos, I will take some time and write a page explaining my experience with silver soldering. It again is about cleanliness of the parts, a good flux and getting the right amount of heat in. It is worth making a hearth if you haven't done so already - I made mine from woodstove blocks. Also, for silver solder start with a high silver content as this will melt at a lower temperature point.
Best regards, Nigel

 

[marcros]

Hi Marcos, I will take some time and write a page explaining my experience with silver soldering. It again is about cleanliness of the parts, a good flux and getting the right amount of heat in. It is worth making a hearth if you haven't done so already - I made mine from woodstove blocks. Also, for silver solder start with a high silver content as this will melt at a lower temperature point.
Best regards, Nigel

thank you, that would be appreciated when you have the time.

 

[Phil Pascoe]

A silversmith I did a course with many moons ago used to flux the pieces - don't allow any flux to get where you don't want solder to show - and then leave the assembled piece overnight to dry. It helps avoid the pieces moving as the water in the flux boils. That was for blowpipe/torch soldering, but the principle is the same.

 

[Argus]

I was a Refrigeration engineer some years ago and although joining copper pipe used a flux-less Eutectic rod with Oxy Acetylene, Copper to brass or Copper to Steel pipe joints used a high silver content silver solder because of its good capillary action penetrating well below and into the union. As ever, solder goes where the flux goes and flux economy was a good idea because it save laborious cleaning of unsightly scabs later. This was with high pressure systems using the dreaded CFCs.

We also used to join single-core Pyrotenax defrost heater cables with silver solder, which required a minute blob on the end of a very thin cable end the size of a pin-head, followed by a fancy air-tight seal - all brazed with silver solder.

I got taught proper brazing with brass rod..... which I found very interesting.

 

[Rorschach]

Up until the last I suppose 150 years that was the way all silver soldering was done, no fancy thermocouples back then either, a great skill.

 

[Rorschach]

A silversmith I did a course with many moons ago used to flux the pieces - don't allow any flux to get where you don't want solder to show - and then leave the assembled piece overnight to dry. It helps avoid the pieces moving as the water in the flux boils. That was for blowpipe/torch soldering, but the principle is the same.

I sit my pieces on top of my hot pickle pot, the flux dries in a few minutes.

 

[Fergie 307]

Nice joint but not really understanding why you are using a kiln. Very easy with proper oxy torch once you get the hang of it. Most important thing is to use the correct flux. Some are intended for thin work where the heat will only be applied for a short time. Others specifically designed for heavier work where the heat will have to be applied over a longer time owing to the thickness of the metal. As others have said, wherever there is flux you will get solder so be careful how you apply it.

 

[Argus]

"Nice joint but not really understanding why you are using a kiln. Very easy with proper oxy torch once you get the hang of it. ..................."

I thought that, too. Much too polite to ask.

 

[Nigel Taylor]

I thought that, too. Much too polite to ask.

Yes, agree to all, just in a home model making environment I don't have access to an oxy torch. It tends to be a butane/propane torch with a fairly big flame. I agree it is not too hard to do. The kiln method was a chance to try a different technique to see what can be achieved.

 

[Fergie 307]

Yes, agree to all, just in a home model making environment I don't have access to an oxy torch. It tends to be a butane/propane torch with a fairly big flame. I agree it is not too hard to do. The kiln method was a chance to try a different technique to see what can be achieved.

Very interesting, not a method I have ever tried. Be good to see some other pieces once you get into it.

 

[marcros]

is silver soldering a suitable method for holding 2 pieces at a right angle using a butt joint? I need a method of doing so for 2 pieces of 1/2" brass or bronze bar. I dont have access to TIG.

 

[MusicMan]

is silver soldering a suitable method for holding 2 pieces at a right angle using a butt joint? I need a method of doing so for 2 pieces of 1/2" brass or bronze bar. I dont have access to TIG.

It depends entirely on the forces to which it will be subjected. What is the application?

In principle yes, use the strongest (highest silver) composition, make sure the two pieces are flat and that the solder is pulled into the whole join by capillary action. As said it all depends on flux. It will have the strength of the solder rather than of the brass or bronze. Brazing would be a bit stronger. But mind you don't melt the brass, it is actually quite easy even with a gas torch. DAMHIKT .. on a piece that needed a day's machining first...

This is done all the time in musical instrument keywork with smaller components, but the loading is low.

 

[marcros]

I was thinking something along the lines of this table frame.

https://www.gregklassen.com/product/archipelago-series-table-no-2
Brazing may be a possibility. I imagine that you were not best pleased after melting your piece!

 

[Nigel Taylor]

If you get the surfaces flat, pickle the parts to clean them, flux in the joint and silver solder you will get a very strong joint. You can always make a test piece and test the strength.

 

[marcros]

a silly question perhaps but how do you hold the pieces for soldering? with welding magnets and fixtures seem to be the way forward but with soldering/braising these are a heat sink aren't they?

 

[Nigel Taylor]

Tends to be either a register to locate the position, a small pin joint/bolt or just resting. Sometimes I wire the parts together. It can be difficult with lightweight parts as the torch blast can move them, hence me trying to use the kiln.

You can use fire bricks to hold parts. If parts are large then you can hold them away from the join, but you probably then need some serious local heat such as using an oxy torch

 

[Phil Pascoe]

a silly question perhaps but how do you hold the pieces for soldering? with welding magnets and fixtures seem to be the way forward but with soldering/braising these are a heat sink aren't they?

In silver work iron wire is often used for binding the parts. Copper wire will get stuck.

 

[MusicMan]

I was thinking something along the lines of this table frame.

https://www.gregklassen.com/product/archipelago-series-table-no-2
Brazing may be a possibility. I imagine that you were not best pleased after melting your piece!

Too right! Didn't even look red hot.

Hmmm I think it might be dodgy. That table appears to be box section steel tube, held by corner pieces banged in. There are various products/systems that do the corner pieces. I would think that is a better and simpler method. If steel tube, bracing would not have much surface area. If solid brass, might be too soft after brazing.

Keith