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Leading flux

I'm in the process of rebuilding a bicycle frame and am left with some minor dings and scratches which I want to fill and fair. The tubes are rather remarkably thin and I really do not want to use a file to clean them up. My idea is to use lead solder as a filler and my problem is that I have no idea what to use for flux.

The reason for using a metal filler is that the frame will eventually be powder coated and the preparation used here is a good glass bead blasting and I don't think that conventional painting fillers would stand that, or the high temperature baking.

I do remember my uncle having a bottle of some sort of acid with zinc (I think) strips in it that he used for flux but other then that I don't have a clue.

Anyone help? Cheers,

John B.

Reply to
john B.
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A can of Nokorode gets the job done without the mess of the jar of acid. Pretty much any plumbing flux should work, if you start with the metal mechanically clean.

Reply to
Ecnerwal

I would go to an industrial hardware store or a radiator shop. Plumbers are no longer allowed solder that contains lead. I buy my flux for 50/50 solder from Marshall's Industrial Hardware in San Diego.

Reply to
Nadogail

I need yo buy mine in Bangkok :-)

Reply to
john B.

--Screw the lead; use Bondo! Either way it's a non-structural fix so what's the diff?

Reply to
steamer

Because I'm afraid that Bondo won't stand up to the curing temperature needed for powder coating.

Reply to
john B.

John If I were in Bangkok, I would ask a local tinsmith where he buys his soldering flux.

Reply to
Nadogail

They all flange up the galvanized but sometimes solder stainless.

But someone already put paid to my scheme as they say that the curing temperature is too high to use solder or body lead. I checked several web sites and they all say "you have to remove all bondo and lead".

Back to the drawing board :-)

Reply to
john B.

They all flange up the galvanized but sometimes solder stainless.

But someone already put paid to my scheme as they say that the curing temperature is too high to use solder or body lead. I checked several web sites and they all say "you have to remove all bondo and lead".

Back to the drawing board :-)

Reply to
john B.

I've built a few bike frames with modern (thin) tubing and understand your reluctance to file on the tubes. Assuming the frame is steel and the tubes welded together, are you trying to improve the appearance of the welds? If that is the case I would probably use 45% silver brazing to fill. Silver can easily be shaped with a file and emery cloth, just be careful not to file on the tubes themselves. Re-reading your post, I would recommend silver for dents and dings. You can place the filler right where you want it and leave very little filing, just takes practice and heat control. Use a water-soluble flux and cleanup is easy.

Reply to
lbgary

No, it is a lugged steel frame, which I am guessing dates back to the

1980's based on being 7 speed with Shimano 600 components, and of course has its share of dings and scrapes, none of which is in itself is damaging to the frame but do rather stand out in a nice shiny powder coating and I wanted to smooth things out. They are the kind of things that if I were painting the frame would be covered easily by a coat of epoxy high build primer with no problem. . After the discussion here I am decided that using low melting point silver (which I can get here) is the way to go.

As usual I was attempting to do something "the easy way" which turned out to be the wrong way :-)

Reply to
john B.

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