[Captin Kirk]

I am having a lot of trouble with silicone bronze. I have been tig welding for around 5 years and can run decent beads on carbon, stainless and aluminum, however I cant seem to get the hang of silicone bronze on mild steel. I am working on a motorcycle gas tank which is pretty thin metal. I want to go over my welds with silicone bronze to make sure it wont leak. My beads look more like "blobs" , I have tried 1/16 and 3/32 filler and both turn out the same. Any help will be much appreciated!

[Otto Nobedder]

Have you considered pressuring the tank to, say, 5 psi, and leak-testing it with soapy water (best formula for small leaks--- 1 qt water, distilled if you have it, 1 tsp Palmolive original formula, 1/2 tsp glycerine, but Dawn in tap-water will do)?

The "insurance" of silicon bronze may be unneeded. If the tank will hold air at 5 psi, it's already tight.

Steve S

[Oscar]

What kind of joints are these? How much amperage are you using? Foot pedal? Torch mounted on/off switch? have you tried 0.045" rod??

So much missing information it's not even funny

[Captin Kirk]

What kind of joints are these? How much amperage are you using? Foot pedal? Torch mounted on/off switch? have you tried 0.045" rod??

So much missing information it's not even funny

I was looking for advice on technique when welding with silicone bronze that I can apply to any situation. It is my understanding that it is more of a brazing as you are not fusing the base metals, if so how do you get the puddle going? Do you light up on the rod or get a puddle going in the base metal like normal. Do you dip the rod any differently? That type of stuff.....

[Riverrat]

Hey captain, when i use silicon bronze i will get the material hot enough to melt then back of the foot pedal just a little then add filler. It is like brazing but it still has to be hot and a some mixing of the base metal and bronze shouldnt hurt in your situation. Hope this helps. Good luck.

[Oscar]

I was looking for advice on technique when welding with silicone bronze that I can apply to any situation. It is my understanding that it is more of a brazing as you are not fusing the base metals, if so how do you get the puddle going? Do you light up on the rod or get a puddle going in the base metal like normal. Do you dip the rod any differently? That type of stuff.....

Well generally speaking, I've found that when I want to braze things up quick so I don't over heat the metal or surrounding areas (if they are painted/coated/etc), heat up the base metal to the point of making a tiny puddle. "Tiny" depends on the base metal thinkness and the filler rod diameter. But once you have a tiny puddle, the base steel is hot enough that just touching the SilBr rod to the hot steel will cause it to melt so long as you apply it very close to the puddle. The puddle itself will be @ ~2800°F, so just immediately outside the puddle should be hot enough to melt the SilBr rod, which melts under 2000°F. Then just move fast and dab dab dab. A key thing to note is that to keep the heat input to the base metals as low as possible, you need to keep a really tight and steady arc. Otherwise you may as well just weld the damn thing, lol.

This obviously isn't the only way to do it, it's just the way I do it. The best way for you to experimentally find your sweet spot is to use varying amperages. For example, for a given joint and metal thickness, try 60% of the normal welding current and see if that gets the metal hot enough to melt the SilBr rod when you touch it to the metal. If it does not, try going up 5% at a time. If it does, also drop the current down 5% at a time in order to find out the lowest setting that will still melt the rod upon touching the base metal.

[robtg]

If you are just trying to prevent leaks, why not flow solder into the weld area?

[Captin Kirk]

Thanks for the advice guys. I think I really need to work on my travel speed after reading your comments Oscar. I know it maybe overkill going back over the welds, but it is a skill I would like to learn, so no time like the present to start trying.