Dad was able to heat those large thermal mass pieces with a bottle of something....what?
He used propane-but my brother brought over a tank of "Mapp Gas"
thinking it might be helpfult for our application-(MAPP gas is also used in combustion with air for brazing and soldering, where it has a slight advantage over competing propane fuel due to its higher combustion temperature of 2,020 °C (3,670 °F) in air.) As it turned out the brass/silver solder heat exchange worked for us.
Did you consider brazing as the resulting color of the weld would have been the same?
I first asked Dad about braising-He siad he had only done braising with brass to steel and suggested we try the silver solder-first. I am OK with the the difference in tone of the SS/Brass- It filed/sanded out well and I kind of like the visual- I'll take close up shots later of the project...
Imagine the nice mortises one could make with a milling machine.
As I have used a Bridgeport on the Day Job for the last 20 years-I have always been amused by the efforts put into router/mortising jigs etc by we "woodworkers" ..I have at time brought my WW pieces in just to used the Milling Machine!