This process aways intrigued me and wondered why it isn’t spoken much in the framebuilding community? I messed around with it a little but had a hard time between that fine line of getting the base material hot enough but not too hot where the base material begins to melt. Does the process or filler material just not provide a strong enough joint like a TIG or fillet would of created?
It is fine for attaching brazeons and such. For full joints it’s basically impossible to build big enough fillets without having them crack while cooling (you’re applying very localized heat, rather than the broader/more even heat from an O/A torch).
It can be good for joining odd dissimilar/fragile stuff (not bikes). I’ve repaired food/beverage/brewing equipment in the past where melting the base material was an absolute no-no but we could not heat up the whole area safely to braze with a flame.
I know you want the least amount of heat cycles going into a joint. Though could you do a second pass with a TIG torch with the pulse on over a fillet to help clean it up or would that localized heat also cause possible cracking? I just thought of it while watching a video of Tom Ritchey doing a clean up pass that helped with filing/sanding and smoothed out the fillet.
AdamR83 on mtbr forum made a frame using Tig brazing. If you search “steel singlespeeder home build” you will probably find the thread
I personally would not try that, you’d just boil LFB with TIG if you were using enough heat to melt the whole surface area of the fillet to smooth stuff out. And you would not want (IMO) to use silicon bronze to build a fillet like that.
If you can TIG braze, you can presumably TIG weld, and as such, you should just TIG weld if you’re going for speed/efficiency. If you want the fillet look, just use a flame.
So really, the answer is “because TIG brazing is worse than normal brazing and also worse than TIG welding so why bother.”
When I was searching for it’s use in framebuilding a few months ago I came across his build and remembered he had it crack a few times right in the middle of the joint.
Thanks for the clarification on this question I’ve have on the back burner for awhile and just a rare lurker on MTBR and honestly don’t do forums much anymore. I just caught wind of the this forum from the SU&BB episode with Daniel and his recent IG posts have caught my attention.
Thanks for you honesty on the question and it’ll put my idea of going further with process to rest.
Thanks for joining! All questions are worth asking and re-evaluating as tools and workflows change over time. I moved this question to Education.
On this brazing topic , @manzanitacycles had some good insight:
The TIG stack of dimes raw fillet look seems to be popular right now. I get it. It saves a ton of work cleaning up the fillets to make them smooth. BUT if your fillet has a thick edge beware that you’re creating potential stress risers. Several years ago a friend requested that I leave the fillets raw on his hardtail. After a year or so of riding, he took the bike off a small drop and either the top tube or the down tube (not sure which) cracked right at the fillet edge causing the whole head tube to pop off! Luckily he walked away with only some bruises. The fillet joints were perfectly intact. It was a tube failure. I can’t say for certain whether it was an imperfection in the tube or a stress riser from the fillet edge that caused the tube to crack. But I always file my fillets with a smooth transition to the tube to be safe.