Framebuilders - Best way to practice brazing???
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12-30-11, 07:52 AM
I've got the bug, have a torch, but want to know how to start practicing brazing. I read the book "lugged bicycle frame building for the first time builder" by Chimonas. In the book it says to get some inexpensive chromoly tubing with two sizes that one slips inside of the other and I don't think that would be possible to get them that are tight enough to do this but maybe. I think ceeway had practice lugs and tubes. Any other ideas, best place to buy flux, bronze, silver? Should I concentrate on Bronze only at first or only silver, both? Any help is much appreciated. Thanks al.
12-30-11, 11:59 AM
Given the book you cite, does this mean you have air/propane? Because bronze will be a real frustration if that's what you have. If you learn to use bronze, silver should be no problem, and bronze is considerably cheaper due to mindless speculation in precious metals.
Nova Cycles also has practice lugs
if the outer tube has .058" wall, they fit together pretty well. I recently did this for learning how to braze lugs with brass. It always bothered me that I was afraid to do that, so I spent some time practicing.
The only issue is that the outer tube is quite thick, so it's best to turn it down on a lathe.
You can buy flux/bronze/silver from Cycle Design or Henry James
See the suppliers thread (http://www.bikeforums.net/showthread.php/775610-Framebuilding-Suppliers?p=13370062&viewfull=1#post13370062)
12-30-11, 01:34 PM
I have oxy, acetalene torch. I'm just going to use the brazing tip that came with it, unless if there is a different one I should use. I'll look into the .058 pipe. Thanks for your advice.
12-30-11, 04:10 PM
what torch/tip? I think experienced framebuilders are separated into two camps: some like to use exactly the right tip for the job, and others like to use the biggest tip they can get away with.
My experience with brass was that with the practice tubing I could use a moderate size tip for rings about 1" in length. But when I tried 3" long rings, I didn't have enough heat. I did manage to trick the brass into penetrating the full length of the sleeve, but it was a travail, and I got a lot of carbon precipitating out on the surface of the sleeve. So I got the biggest tip my tanks could support, and it was a piece of cake. You need approximately 7 times that volume of acetylene than the tip will flow or you start to burn acetone, which is bad news. For my Smith AW1A, I ended up with the AW207.
I haven't tried a lug with brass yet. When I get ready to build a bike that way I'll probably do some more practicing. The real utility of the sleeves for me is on fillet brazed frames at the seat joint
01-24-12, 07:07 PM
Tri... I have two lugged frames that are not collectable you could have to practice on. One is a '60 heavy gauge with a weak rear triangle and bad lungs. The other is a just a heavy early '80s chromoly of some sort. PM me and we can arrange a meet where I can hand them to you.
You are doing something I've wanted to try. Mostly I want to add or modify some braze-ons once in a while. Anyway, happy to contribute cannon fodder.
Andrew R Stewart
02-01-12, 09:56 PM
Good ideas all. One practice method I've used is to play with the torch and bronze/brass in making shapes and forms out of filler. Stalagmites raising off a tube. Chasing a drop of filler around making a letter or heart shape. Another is to practice fillet joints on a flat plate of steel with tube stubs. Quick to prep, gives you experience in heating joints with differing thicknesses of materials and is easy to peer inside to see if you flowed an internal fillet. Here's a practice "lug" made from 1.125 x .058 wall over a 1" tube. the pin holds the sleeve in place. Andy. 235797
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