very useful, peter. I haven't completely settled on design yet, but I'm leaning toward something like this but with perhaps a second cross member
http://www.velo-orange.com/nimfrra.html

It's a small rack so loads will be limited but the fact that it'll attach to thee canti studs will be a limiting factor... also, I will not be squishing the tube...I'll cut a slit and braze some flat stock in there.

in the end, I'm guessing it'll carry a sixer but not a 12 of beer.

I think I'll start with a can of MAPP and some silver braze and probably use SS--there is a place in town that stocks quite a lot of SS and 4130 tubing, so here goes@

Thanks again!
Allan