Forums.NitroExpress.com

Andreas,

I use a wire. Although I see no reason why ribbon shouldn’t be just as good. Maybe it’s better. I just guess I’m happy with what I am using, and I’m a great believer in “if it ain’t broke, don’t fix it! But one day I will try it. Time.

The silver brazing wire I use is a Bohler product, UTP306M. It has a 55% silver content, flows at 650 C (1202 F) and has a tensile strength of 430 MPA (62,366 PSI)

The flux is just a common low temperature silver brazing flux paste with a working range of 575-825 C (1067-1517 F)

I clean the joint, flux it and twitch the barrels, shoe-lump and top extension components in their respective places with 1/8” mild steel wire. Then the alignment is double checked on the machine plate with parallel bars and the muzzles measured with a micrometer to make sure the initial convergence is still right. When I'm happy with the set-up, generous amounts of silver brazing wire are laid on the joint and the breech end of the assembly is carefully slid into my pre-heated brazing furnace till the braze flows. Because my joints are well fitted, well cleaned and heated correctly, when it is all up to the right temperature, the solder flows and capillary action draws the silver braze through the entire joint.

There are a number of silver brazes available on today’s market (see ronvella’s comment above on true silver solder/braze), and if the one chosen is from a reputable manufacturer and it has the correct temperature and strength properties, provided the joint is fitted properly and it’s clean, one silver braze shouldn’t be vastly superior to another.

The most important things with this process are,
The joint MUST be fitted correctly.
The joint MUST be clinically clean before the flux is applied.
The assembly MUST be properly secured together during heating.
It simply MUST be heated correctly and evenly, defiantly NOT over-heated. An oxy/acetylene torch is NOT the way to do this joint!

If someone was to ignore these basic yet vital points when silver brazing a shoe-lump joint, or any other important joint for that matter, they are on their own.

Once again I’ve gotten a little long winded, but I trust it has helped.

Alex

alexbeer.com

--------------------

Details matter!

Post Extras