dgranger@comcast.net wrote:
> FWIW, Ross was using "salt-bath brazing" for their cheap frames 25
> years ago...
>
> the process worked only with "gas pipe" quality tubing - when they
> tried it once with a triple-butted Tange tubset, what came out
> resembled a pretzel more than a bike frame. This according to Tom
> Kellogg, who was building their Signature frames at the time... I
> have a Ross brochure from 1980 that shows the "salt-bath brazing"
> line - looks like a foundry!
The problem with salt-bath brazing is that it heats the entire frame to brazing temperatures -- the frame is tacked together and loaded with brass "bombs" in the joints so when it is immersed in the molten salt it melts and flows through the joint. It's an elegant process in its own way, but as you note not well suited for thin-wall tubes. I suspect the tubing is softened enough by the heat that the process of pulling it out of the bath is enough to distort thin tubing.
--
John (john@os2.dhs.org)
Appleton WI USA