Just a comment or two.

If you Google Do-All you can find instructions for the blade welders on
their saws.

I silver solder my blades with a jig similar to the one a previous
poster showed. Mine evolved over time and is nowhere as nice as his. One
thing I have added that I find very helpful is a round carbon rod the
end placed under the weld area level with the blade bottom. After I see
that the solder is melted, I remove the flame and press down with
another piece of carbon and squeeze out any excess solder. This gives
you a flatter joint. The solder and flux I use was bought some 50 plus
years ago to make a bracelet for my wife.

CP