black goo appearing in flux. gasfluxer suspected.

[dbohemian]

Without paste flux? On occasion- though not generally for bike tubes. I do however tack with way less paste flux then many people. I preload the insides of tubes, but don't generally slather it on until I am ready to do the actual structural joint (and even then I usually don't use as much as some folks).

I think the advice about how much flux to use depends on the experience of the user and the cleanliness of the parts. Flux provides a barrier to atmospheric oxygen and through chemical action absorbs oxides that are produced during brazing and cleans the parent material of oxidation. Flux is used up either through long heating cycles, high temperatures, dirt and oxides or a combination. Experienced brazers just naturally move faster thus putting less load on their flux. They also have better heat control and the parts are prepped better (cleaner). For the inexperienced brazer additional flux can go a long way in preventing premature degradation. For the experience it is not as necessary and really you only need it where the actual brazing will be taking place which saves money and cleanup. Additional flux though can never really hurt anything so when in doubt I always tell them use more. Plus since I sell it, it is like a pusher telling you how good it is for you. I will say, I see WAY more problems caused by people not applying enough flux.

[edoz]

When Tom Ritchey did his seminar at NAHBS, he said he uses no topical flux. He does everything with just the jetfluxer, as he called it. I tried a couple of test joints that way but it didn't work out for me, but it sure works for Tom.

[boxer bicycles]

Side bar- I ended up running a splitter at my regulators and have dedicated silver and brass torches with only the brass lines running through the Gasfluxer. In a pinch the "juiced" torch works fine for silver, but the pure gas seems to work better for silver with type U.

Eric, this thread is stale, but I wonder if you have any photos of your set up? Is the splitter after the regulators or do you use two sets of regulators? Thanks.

[Eric Estlund]

No photo at the moment, but I can take one when I hook the tanks back up. I run a Y-valve at the regulator, with one hose set to the fluxer and flame saver for brass, and another straight to the silver torch. I recently acquired another double flame saver (I think it needs a rebuild)- I may end up running two brass lines and a separate flame saver/ silver/ no flux set up.

[Eric Estlund]

Here we go- the fluxer normally sits on the floor, but this seemed easier to read: