Hi there !
I’m okay at brass brazing so I believed that I could go for silver brazing without trouble. Then I directly tried to silver braze unicrown fork with SL inox hooded dropouts.
It was dumb.
I stoped at tacking when I figure out. I’ll clean eveything and come back at it after reading your advices and practice.
I did use system 48 paste flux and saldflux ternalloy 30 (30% silver) to “join” the fork legs to steel steerer.
Here the flux ran and the silver was sparkling and wouldn’t do a liquid pool. It came with matt finish.
I used stainless light flux paste and the same ternalloy30 for the inox dropouts. It came a bit better but not good.
Both fluxes are around 8 year olds and crispy.
So I conclude that I’d need new flux and practice. Am I right ?
I’d like to try silver black flux wich hold longer/better. Am I right ?
About cleaning. Must I use acetone or IPA does the job ?
I do not have a photo of the silver tacking mess but I join one of the last unicrown fork I made with brass so you can figure about my torch skill.
I thank you in advance for your answers.
Happy new year.
Kiss
I have acquired a set for brazing- bug tanks of oxygen and acetylene, hoses regulators, etc. now I need to get all of the other stuff! I’m fairly clueless, I’d love to see what tools/accessories everyone would recommed-
I prefer wood tube blocks, round not vee. Easy to make them yourself, one for each diameter. A chunk of bike tire makes an excellent hinge. It acts as a spring holding them closed, so they cling lightly to the frame while you’re positioning it.
Though I’ve never used one (or wanted one), there is a mag holder with an adjustable angle. I forget who makes it, Strong Hand maybe. Set the angle with a bevel protractor.
About flux — don’t use the stuff the local welding shop sells, it’s usualy terrible. They’re most likely to sell only silver flux anyway and you mentioned brass. Cycle Design (mentioned elsewhere in this thread) is good but they’re out of business. Of the brass fluxes you can buy now, Gasflux brand might be the best. Note they call brass “bronze”, don’t be put off by that, it’s two words for the same thing. The welding/brazing industry settled on calling it bronze for some reason.
The wooden blocks are also useful to using tubes that may not be perfectly round like tapered tubes, shaped tubes, or even really small diameter stuff like racks and seatstays plus they have less chance of damaging or crimping if clamped too hard.
I would also add a big bucket or storage container to soak off flux, maybe a fan to get air flowing (if you’re working inside), and something to cover your mouth/nose so you don’t inhale fumes while brazing (the stuff that comes off flux smells gross when burned and it’s probably not good to inhale). Some basic glasses to protect your eyes. Gloves to handle hot stuff (I use basic leather gloves from the hardware store)
I am not sure if it has been listed and I have not found but what type of brazing is used where. Why use silver instead bronze and wise versa. I am getting setup and need flux and filler. I am using it mostly for bottle bosses and cable mounts. Thank you
When molten, silver filler is much runnier than bronze. So silver is better for small gaps and tight fits, like lugs. Bronze is better for large gaps (e.g. dropouts into fork blades or chain stays) and fillets. Silver also melts at a much lower temperature than bronze, so it’s better for small parts that don’t need a lot of heat, like braze-ons. That said, silver is also MUCH more expensive than bronze. Some builders only use bronze and use it for everything, but I’d guess that you need really good heat control to not cook things. Another reason to use silver (or nickel silver) over bronze is if you’re joining stainless steels. Bronze won’t stick to stainless, while silver and nickel silver will.
I’ve always put cable guides on with the same filler I use for fillets - sifbronze 101 and cycle design LFB paste. If you’re using mild steel bottle bosses it will do that too.
There’s still some of the LFB paste knocking about (I think Peter at Ceeway has a stash) but the gas flux equivalent should work great too - type B I think? Can somebody confirm, I’m not familiar with it.
