Originally Posted by guy153

I am using a gas lens with a No 8 cup, and about 10lpm which is about 20cfh, but I go to 12lpm if I'm in one of these tricky spots with extra stickout needed. I've tried a much bigger cup with more stickout but I found the big cup gets in the way and you need even more stickout... so kind of a vicious circle. Maybe my big cup is too big. You also always need some pre-flow with that setup because there's such a big space you're trying to fill up with gas.

I used the foil in three places: bottom of DT/HT, where the ST joins the DT, and CS to BB shell. ST/DT I probably could have got away without it and possibly DT/HT as well but I dunno... it was quite a lot of stickout. Never tried backpurging as not attempted stainless or Ti, but I know some people do use it for CrMo as well.

How did you manage the back of the SS to ST on a road-style frame with a horizontal TT and quite a long ST with is about 30mm diameter at the top? That's like a 57 degree angle and with the two stays very close together. I've found it's basically impossible to reach inside there, but I can TIG braze it. I make a bigger fillet that's sort of bridging across a bit (which means I can reach it) and then I can zap the fillet with the torch and it kind of falls in. Actually seems to work quite well.