Questions about silver solder

[Ed ke6bnl]

What are you using for heat. I tried that today with Map and no success getting it to flow

I prefer oxy / acetylene

 

[Hawkeye]

About 9 years ago, I picked up a small kit from the local welders supply. It consisted of one troy ounce of silver solder (45% silver, cadmium-free) and a small pot of flux. IIRC, it cost about $27 at that time. That was before metal prices went through the roof. I've used it for many small projects since then and still have about 1/3 left. One project was to repair a broken shaft on the cross-feed on one of my lathes. I used a slot-and-tenon joint and flowed the solder into it. As mentioned above, oxy/acetylene is the preferred heat source, but I think I used two propane torches in this case.

 

[GrifterGuru]

Personally, when silver brazing (which is what it silver soldering is despite the name), I use my oxyturbo kit (Oxygen + Fuel Gas [mainly MapGas]).

The OxyTurbo torch gets the subject material up to temp quickly and the silver solder (silver braze) flows nicely. I never have had success with a map torch despite playing around and trying the various tips supplied with it.

That said, I use 55% or greater silver solder (silver braze) and have had zero issues with the flux paste that I use. The diameter of the rod / solder wire depends on the intended use. Thinner wire is good for close/tight joints, bigger diameter wire/rod is good for building fillets or bridging gaps. Smaller diameter flows more quickly than larger diameter wire / rod.

The trick is to get everything to an equal temp that is just enough to flow the silver, no more, no less. You can actually see when you reach temp because the silver starts to look paste-like before it snaps over to flowing, like soft soldering, only at a much higher temp.

Managing temp is the key. You need to know what temp the silver will flow at and once you know that, you will know what heat source is required. You will also need to ensure BOTH parts are clean and both are at or within the same temperature range avoid joint failure through unequal stresses when it has cooled.

I generally allow silvered / brazed joints to cool naturally rather than quench, which can induce multiple stresses, then gently reheat to a lower temp temp using a map torch and allow to cool naturally once to more to stress releive the joint further. Never had a joint fail.

Either way, there will always be a HAZ (Heat Affected Zone) no matter what you do, you just have to be mindful of that altered material state.

 

[woodchucker]

I silver soldered my carbide on using harris stay brite kit. Worked fine. A round carbide, it has held. I use the tool for forming

 

[Flyinfool]

Most of choosing the correct filler and process for a joint is the design of the joint and the forces that will be acting on it. The best for one application can be all wrong for another. That is why there are so many different processes and fillers available. There is no one best way for everything.
There are some brazing alloys that are like water in the liquid state and others that are like honey and everything in between. The right one depends on the configuration of the joint.
Can you post some pics of the parts and or drawings of the joint?
An ideal joint will be mechanically secure before the braze is applied.

 

[verbotenwhisky]

I've seen people that braze carbide to steel for cutting tools using oxy-acet torch using regular brazing wire and flux. also have seen others that use silver solder. Some use pastes some use foil. I am soon going to be needing to join a hardened acme threaded rod to the cross-slide handle for my lathe. I've done a lot of regular brazing and also tig and stick welding in my past but not very educated on which silver solder to use and what temperatures it requires. I've seen quantities of paste on eBay and Amazon that are in syringes and mostly advertised for electronic work. I am assuming I need to stay away from this paste for the repair I need to make. How ever if I could use a map torch and good grade of silver solder, I think that would meet my needs. So what solder what paste what heat source and what kind of clearance (fit) do I need to make a good joint? Any experience on this subject will be greatly appreciated.

I like the Harris Safey-Silv 45 and use it with the white paste flux, I have an Oxy-Propane torch which I put a #00 tip on and it does a good job.

 

[Nesse1]

How tightly do the parts fit together? Can you create a slip fit with just a few thousands between, along with a reasonable surface area for the bond? If so, I'd use 56% silver with white flux to match.

Slather the parts with flux. You can't use too much. Warm the joint. The flux will dry out as the water is driven out, and turn into a chalky scale. As the parts reach temperature the flux will turn clear and flow. The metal will be medium red. You don't need orange metal with silver. Add the rod and it will suck into the joint. Fill until the joint won't take any more filler. Then let cool. To clean off the hardened flux, use hot water.

 

[strantor]

I got some of this "extra easy" solder and this Flux and I use a #00 acetylene torch with it. Works well. I don't think any certain fitment is necessary. Soldered copper tube to stainless plate, just laid it on there and flowed the solder, it became like a solid piece of metal even though it wasn't pressed together and only bonded on one side.


Plumb Silver Jewelry Solder Easy, Medium or Hard … (Extra Easy Silver Solder) https://a.co/d/cCcQAgy

GSParts Harris Stay-Silv Silver White Brazing Flux Paste for Hi Temperature, SSWF7 https://a.co/d/9H6g213

 

[verbotenwhisky]

How tightly do the parts fit together? Can you create a slip fit with just a few thousands between, along with a reasonable surface area for the bond? If so, I'd use 56% silver with white flux to match.

Slather the parts with flux. You can't use too much. Warm the joint. The flux will dry out as the water is driven out, and turn into a chalky scale. As the parts reach temperature the flux will turn clear and flow. The metal will be medium red. You don't need orange metal with silver. Add the rod and it will suck into the joint. Fill until the joint won't take any more filler. Then let cool. To clean off the hardened flux, use hot water.

The joint in my picture I actually machined the fitting to fit the curve +/-0.002, I get good results on these joints, I was installing a drain in a friends Mercedes Transmission sump pan. If you look close you'll see a small hole, there is a second on the opposite side, this was for a stainless wire which also was to run through the plug to insure it didn't back out.

 

[rwm]

Delete me. If you read this already be aware that this is highly dependent on the alloying metals.