Which is better? Brazing rods with flux Or without flux

[mickri]

Looks like I am going to try some brazing. Is it better to use rods with flux? Or have the flux and rod separate. I will be brazing .065 wall exhaust tubing. I know nothing about brazing and have never done it.

 

[FOMOGO]

If you've never done it before the coated rod may be a little easier, as you will have a little less to pay attention to. Other than that not a whole lot of difference. On heavier work I like being able to apply flux directly to the prepped area before adding filler, but on your thin wall material it should be a non issue. Mike

 

[Norseman C.B.]

I personally prefer using bare rod and common 20 mule team borax for flux
more bang fer the bux....................

 

[C-Bag]

I have better luck with the non fluxed rod. Just got to remember to dip your heated rod in the flux all the time. Brazing is a great way to go. It’s a lot stronger than you think if it’s done right. It’s all about prep and getting it to flow. My first project in metal shop was to take two 3/8 thick plates, v them and braze them together. Then you had to bend them in the press until the ends touched without the weld breaking. Got an A on that one.

 

[Cooter Brown]

I like the Harris Bare low Fuming Bronze 15 filler with the Black Stay-Silv Flux.........You will need .030-1/16" diameter filler rod for brazing .065 material..... The larger filler needs to get to hot and you burn though the base metal before the filler ever melts....

I actually like using galvanized bicycle spokes as filler for Gas Welding sheet metal it works great for me.....

 

[matthewsx]

Brazing is a cool art to learn, especially for owners of LBC's (little British cars). I did a bunch of brazing on my Triumph TR4 and don't think those repairs could have been done any other way.

I'm with @FOMOGO here, don't really think it makes too much difference except for cost. Just make sure you practice plenty on the scrap from building your header so you know exactly how much heat that metal can take before you blow a hole in it.

John

 

[mickri]

I have leaks where the exhaust tubes slips into the collector that I have not been able to fix. The leaks are where the tubes are right next to each other. This is not to try to actually weld the tubes together. I am just hoping to plug the leaks. I have a 1 3/8 OD exhaust tube that is slipped into a 1 3/8 ID collector tube. There is between 1/2" to 1" overlap. Silver solder would probably work because I don't think that the collector gets that hot. The problem is that when the header is ceramic coated it will be baked at up to 700* to 1400* to cure the ceramic coating. That would melt the silver solder causing who knows what kind of problems. From the videos that I have watched it seams like the bronze filler flows down into the joint. That is what I would like to happen.

 

[matthewsx]

You're on the right track. The only thing I might suggest is rather than ceramic coating you just wrap the header. Ceramic may make it difficult or impossible to repair when need arises, it also costs a lot. Header wrap is relatively cheap, effective, and IMHO looks just as good or better.

John

 

[G-ManBart]

If you can make a similar joint out of scrap to practice on you'll be way ahead of the game. I have both coated an uncoated rods and think it's easier to use the coated rods for someone starting out. After you get a bit of practice it shouldn't matter either way.

 

[Cooter Brown]

You need safety-silv 56 for this project..... Melts at about 1500°F....

Bronze filler melts at much lower temps... Bronze also doesn't wick down into the joint as well as silver does...Bronze does build up easily but it's not great at being a thin layer down inside the joint like you want....