Silver solder and Carbide

Tell more about how you are doing this; heat source, flux, prep??? Are you sure you are aligned with the Earth's magnetic field? Are you trying to do it on a Tuesday?

i've used plumbers silver solder. I think you have a surface contamination problem. it'll drive you nuts and waste gas.

commiserations Stealth Pilot

What are you using for flux? That's more likely the problem than the brazing alloy.

Ned Simmons

Try using some oven cleaner or Lye to clean the carbide.

Dan

At the risk of warming up the terminology wars, are you trying to use silver SOLDER(tin/lead content) or silver BRAZE(no lead or tin)? You need silver brazing filler rod and the appropriate flux for making carbide-tipped cutting tools, also a lot of heat. Depending on the filler alloy, you may need more temperature. Some alloys just can't be used with a propane torch. If you've got enough heat, you can use regular brazing rod, without any silver, and the appropriate flux. A little more about HOW your're trying to do this might bring more helpful responses. List your setup, torch, type of filler and flux and how big your pieces are and you might get some better responses. Also how you're cleaning your surfaces.

Stan

I never could get brass brazing rod (nor phosphor bronze) to adhere well to carbide, but the jewler's silver solder works great - after reading more than I wanted to about brazing carbide, I came away convinced that you need about 50% silver in the braze alloy.

there is an excellent discussion on the web, just search for "brazing carbide"

============== Thanks for an on-topic and useful suggestion. I will have to remember this one.

I'm using some white stuff made by Lincoln and sold at Home Depot. Not sure what it is.

Thanks,

Wes S

At the risk of asking a dumb question, do I do this cold? Do I wash it off with water afterwards?

Wes S

I used to run a saw shop that made SS saws - with proper care, we had no trouble brazing on carbide tips.

Since you've managed to braze carbide to steel before, I'll assume you're using the right silver solder, etc.

I suspect the issue is surface contamination. Stainless won't rust because it has a thin layer of oxides. If this layer isn't removed it will be the weak part of the joint. With SS you have to have a chemically clean finish. Grind or sand the surface to remove the oxides. Use a SS brush - even a steel brush will leave something.

A good flux will help. Black flux is good, but the refined fluxes are great for tough brazing jobs - they seem to clean the surface better and then keep it clean while the torch is on.

Tom Walz's web site - carbideprocessors.com is the best site on brazing.

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