Going to try brazing...

General cycling advice ( NOT technical ! )
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simonineaston
Posts: 2299
Joined: 9 May 2007, 1:06pm
Location: Bristol - work in... Yate!

Re: Going to try brazing...

Postby simonineaston » 8 Apr 2011, 2:19pm

531colin wrote: I would hesitate to weld something myself if my life might depend on it being right....like bike stuff!

Yes, that's why I decided just to stick to the 'cosmetic' stuff, like cable guides and bottle cage bosses. If I get on OK with these little pieces, I'll try making the racks for my ancient Moulton Safari look-a-like. I'm really looking forward to it, now I've heard from you folks and deduced it's worth having a go - I'll probably try to get some decent kit from ebay - Rothenberger? and sell it on when the obsession is over ( and I've moved on to bread-making!)
I remember I did try brazing as part of a college course years ago, but of course I was able to enjoy the use of all the college kit, which included brazing hearths, piped gas on-tap and wot-not. :D
ttfn, Simon in Easton
(currently enjoying a Moulton TSR & a nano Brompton...)

Father Jack
Posts: 237
Joined: 4 Apr 2011, 10:07pm

Re: Going to try brazing...

Postby Father Jack » 11 Apr 2011, 10:19am

Can find out about helicopter, dad has syndicate group putting in costs for heli and plane.

Brucey
Posts: 32762
Joined: 4 Jan 2012, 6:25pm

Re: Going to try brazing...

Postby Brucey » 29 Mar 2012, 7:04pm

yakdiver wrote:Forget brazing and go for a small mig welder, with a special flux-coated wire that produces it's own gas shroud as it burns.


bit late now I know but.... Gasless MIG?

horrible horrible horrible horrible and poisonous.

The wire is flux-cored. In theory this ought to be no worse than flux-shielded arc welding, but in practice it ain't. To get the arc stability anywhere near good enough (I was told) they lace this stuff with Barium, which winds up as Barium carbonate after welding, which (unlike other barium salts which are insoluble and therefore fairly benign) is soluble in mild acid (like stomach acid) , so you can poison yourself with this stuff...you breathe it in then swallow it.... It is also rubbish to work with, (very difficult in thin sections) usually gives welds with rubbish properties, has a very low deposition efficiency, goes rusty double-quick on the spool, and costs a fortune (x4 for a lb of wire, from which you get about 6oz of weld metal tops, generally more like four..).

The only things it has going for it is that you can weld out of doors in a howling gale and you don't need a gas bottle.

A machine that will only take 'gasless' wires is a false economy, no matter how cheap it is. By all means keep a reel for emergencies if you run out of gas or must weld in that howling gale, but otherwise stick to gas MIG where possible.

And for bike frames; last-gasp repairs and fabrication of gas-pipe specials using MIG is fine, but everything else is better done other ways.

cheers
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