View Full Version : New to silver soldering

08-17-2005, 02:56 PM
I have good experience in soldering electronics, but now I want to make small mechanical components from steel. I guess silver soldering is the solution. Could anyone suggest what I need of equipment? (And where to order?)Thanks for any answers!

08-17-2005, 03:05 PM
There are a couple of methods I have been involved in, it depends on the guage and fragility of the object, One method is a very small oxy-acetylene torch with the appropriate gauge rod and flux, I have also used induction heating, with pre-formed Silver solder, very fast and least distortion of the part, with even solder distribution.

08-17-2005, 03:18 PM
I have done both methods as mentioned by Al.

There is nothing really difficult about it - it's just like soft solder except it takes more heat. The flux is more critical than soft soldering, but otherwise has the same function. Just make sure you have intimate contact between the mating parts to minimize the thickness of the joint, make sure both parts are clean and go.

I would recommend that you grap a few rods and maybe a few of the sheets of the solder - both methods come in handy. And keep the flux closed as much as possible.

Give it a whirl and post some pics, darn it!

Good luck!


08-17-2005, 03:32 PM
You can get buy with a plummer's torch which uses air and acetylene, you can get these at your local welding supply, or on-line. If you're just doing a few pieces, I believe a propane torch using MAPP gas would suffice.

08-17-2005, 04:23 PM
For small stuff, the simple $10 butane tourches work great.

08-17-2005, 06:28 PM
Fantastic answers!
Maybe a small torch is the right thing. The parts I will make is for guitars that I make as a hobby. Maybe I can share some pics if I make some OK parts. It seems a bit different to solder with a small jet engine in my hand, but I guess I just have to be more careful.

08-17-2005, 08:26 PM

I've done alot of jewelery soldering. Parts need to be VERY clean and well fluxed. There are multiple different heat ranges of solder, so you can build an assembly with high heat solders first, and add subsequent components with lower melt solders without "unsoldering" your first joints.


08-17-2005, 08:36 PM
Silver solder is used by model engineers frequently, and the epicenter of model engineering, the UK, is close to you. Lots of links for suppliers and books


Think of brazing rather than soft soldering – SS is more like that – ie getting the parts just turning red hot.
Like mxtras said, cleanliness, flux and the right temp critical. A bucket with a sealed lid of 10% sulfuric acid makes a nice pickle for before and after.

Stay away from acetylene unless you’re experience, you can do it by playing the flame, but the flame is too hot and easily burns the flux. Propane’s the right thing to use. If you here someone complain that their handheld bottle didn’t work, it’s not that the gas isn’t hot enough, it’s the torch is too small – not enough btu’s. If your stuff is small, not and issue though. I use a largish torch with changeable tips on a 20lb propane cylinder (very useful for heat treating as well)… then you don’t run out very often.

It takes very little SS to make a good joint, similar to Al’s preformed solder idea, I get the smallest dia SS and cut it into maybe 1/8” long pieces placed into the wet flux along the joint. Carefully heating so as not to blow the pieces away, you get a very neat joint when it all comes to temp.

Another handy idea is a using three refractory bricks to form a corner. They reflect the head so well it really quickens the process.

Both the fumes from flux and solder (cadmium) is toxic, so consider a hood (now you have to learn sheet metal work to) and fan. There are special non-cadmium SS’s if you are making anything for food.

08-17-2005, 08:38 PM
The only thing that does not seem to have been mentioned yet is make sure your joints are nicely fitted; maximum gap 0.010", preferred gap between 0.003" and 0.006". On round joint remember this is on the radius, the diameter difference would be twice this. You flux the parts before assembly then heat in a region away from where you will be applying the silver solder. You want the solder to flow up a temperature gradient and enter the joint by capillary action without solidifying part way. Be very careful to not overheat; the metal is at about the correct temperature when the flux melts and turns clear. It is easy to overshoot and burn the metal so the silver solder does not flow onto the surface.