Is there any difference between oxy/gas welding and brazing?

[MikeSpaniard]

Hi guys!
Im studying welding and fabrication but se are not doing any oxy.
I really want to get skills in frame building (bicycles). There are mainly two process tobuild bikes up: brazing and tig welding. Im learning how to tig weld.
I did ask my teacher about brazing and I was told that the college is not doing any brazing at the moment ( but they doing gas welding oxy).

I also spoke to a frame builder and I was told that oxy/gas welding and brazing are the same thing!

What you gusys think about it cos Im confused and really want to get in the Business!

Thanks a lot

 

[winchman]

Having spent a few years in the bike industry the Frame builder is talking rubbish.
Gas welding both parent metals are fused together and the same metal filler rod added if required
Brazing two tightly fitted components are pushed together and a molten brass alloy is heated and runs in to the gap with help from a flux, I feel brazing is more like soldering but stronger and at higher temps.
With regard to bike building brazing gives a more flexible frame so often used in rural Africa and simpler more readily available tools are used if it ever needs repairing

 

[rtbcomp]

Brazing involves the introduction of a metal with a lower melting point than the metal to be joined, similar to soldering, but the metal used is usually brass based whereas soldering is lead based with a much lower MP. A flux is usually used.

Gas welding melts the metal to be joined, sometimes metal filler is introduced, but this has a similar MP to the parent metal.

Edit - Winchman pipped me at the post!

 

[MikeSpaniard]

Thanks yoi guys for the reply.
So what do you think I could do to get into framebuilding? I cannot find any brazing course here in london, but ive find some oxy courses. Should I take that? Because the grame building courses that offers some Bike shops are massive money and short time ! I cannot afford pay £1500.00 per a 5 or 6 days course..

 

[Dee J]

Framebuilders sometimes confuse the welding/brazing line by referring to the butt joining of shaped tubes with a fillet of braze (and oxy-acetylene) as 'bronze-welding' or 'braze welding', keeping the term 'brazing' for assembling the frame using lugs capillary brazed in a brazing hearth (probably with air-propane or oxy-propane). To a welder this is all brazing, because the filler is dissimilar and the parent metal isn't melted.

 

[Wendelspanswick]

Perhaps the frame builder was talking about the equipment used for gas welding and brazing as the same equipment and gases can be used for both.
Oxygen and acetylene are required for gas welding and can also be used for brazing with bigger nozzles on the torch.
You can also use oxygen and propane for brazing as its cheaper but not for gas welding.

 

[Chris Stevens]

Learning to braze is pretty easy, gas welding a bit more difficult, but still not all that hard. Building a bike frame to a good standard though is something else entirely, and might take several years of practical hands on experience to master.

 

[hotrodder]

Thanks yoi guys for the reply.
So what do you think I could do to get into framebuilding? I cannot find any brazing course here in london, but ive find some oxy courses. Should I take that? Because the grame building courses that offers some Bike shops are massive money and short time ! I cannot afford pay £1500.00 per a 5 or 6 days course..

While they'll be useful from a safety POV i suspect most oxyfuel courses won't teach much that'd be specifically useful for framebuilding. As said the brazing (or welding) aspect of framebuilding is relatively easy compared to other aspects like machining & hand finishing coped joints or fabricating the traditional way i.e. coping joints to a specific angle and a daylight tight fit up using just a hacksaw and file
Luck and blagging ability will play a role but i'd be finding every localish framebuilder (assuming there are any)* and approaching them directly... years ago i managed to blag myself an unofficial apprenticeship with Ron Cooper (RIP), basically doing all the boring/thankless jobs like tea making, mixing flux, cleaning off flux residue, reaming this & facing that etc in exchange for lessons

* i've been out of the bike trade for years now and most of the framebuilders i knew were semi retired back then anyway but Ceeways (framebuilding supplies) used to have a list of framebuilders on their site

 

[Chris Stevens]

I guess the cycle frame building trade has declined somewhat in the face of the quality of frames made in places like Taiwan for a lot less money?

 

[winchman]

I guess the cycle frame building trade has declined somewhat in the face of the quality of frames made in places like Taiwan for a lot less money?

It was 20 years ago but we paid £6 each delivered with forks and ready for paint!

 

[winchman]

Thanks yoi guys for the reply.
So what do you think I could do to get into framebuilding? I cannot find any brazing course here in london, but ive find some oxy courses. Should I take that? Because the grame building courses that offers some Bike shops are massive money and short time ! I cannot afford pay £1500.00 per a 5 or 6 days course..

I would get your self a cheap set up and have a look on Youtube etc, the course is too expensive and the general welding not specific enough.
Get a few old brazed frames and take them apart and re build them for practice.
This company copy all the top stuff and sell it at a fraction of the price
http://www.shuztung.com/bicycle-equipment.htm
The skill is in keeping it all square but often they are just brazed as near as then bent to the correct alignment

 

[mike os]

As the techniques, equipment and it's use are essentially the same if you have the opportunity to do gas welding as part of your course take it....

That way you will learn gas safety, torch and flame setup and to work with both hands controlling and coordinating heat and filler, the only 'real' difference is the temperature and filler for fillet brazing

 

[hotrodder]

The main culling of quality UK framebuilding happened way earlier... the Claud Butler story is fairly well known, others like AS Gillott got sold and sooner or later the new owners destroyed the brand. Some of the frame builders (like Ron) went out on their own and kept full order books until they retired/passed on. Some of the smaller/niche companies just carried on

Being able to buy a Taiwanese 'unbranded' knock off for less than what the tubing would cost doesn't come into it really. Totally different market

 

[winchman]

Being able to buy a Taiwanese 'unbranded' knock off for less than what the tubing would cost doesn't come into it really. Totally different market

Its very interesting how a small change in geometry to suit the individual can have a massive difference on how it rides. Our son mainly rides BMX and a couple of years ago changed his frame for a 1" shorter one and finds it much better.
I am sure the keen cyclists will tell you how having an exact fitting frame is better and why, but the vast majority of us just use an off the shelf cheap one, from memory most of ours came from India as Taiwan was too expensive! We shut our own frame building in the early 90s as we just couldn't produce the volume needed with out massive investment so it was a quick fix to buy them in.
You cant beat having a go at building your own though, its not rocket science just think about it and plan then build a jig then just have a go but be prepared for the first few to be wrong, you will get it right after a few attempts.
So post some pics of your attempts

 

[pickmeup]

im looking Into learning to braze as I have a caterham chassis to repair. theres a company in frome somerset that do courses on bike frames. but ive heard the 1day intensive course is very good.

 

[brightspark]

if u allready have oxy acetylene bottles and a welding torch just have a go. its not rocket science. theres plenty of vids on u tube to give u a clue . there was nothing when i started brazing and welding just kept at it till proficient

 

[winchman]

im looking Into learning to braze as I have a caterham chassis to repair. .

Well I was just about to say that as far as I am aware they are welded but then googled it first
http://www.pistonheads.com/gassing/topic.asp?h=0&t=217343
I made one many years ago and just Mig welded it, but if its a proper restoration its best to keep it original

 

[Chris Stevens]

im looking Into learning to braze as I have a caterham chassis to repair. theres a company in frome somerset that do courses on bike frames. but ive heard the 1day intensive course is very good.

You might want to look at TIG brazing, its easier than gas in my view, you only need one bottle, and a DC TIG inverter isnt a lot of money.

 

[citizen kane]

Its been mentioned before but I dont think that TIG brazing is a suitable process for this. I've tried it before when frame building, it dosnt seem to flow, might be OK for attaching cable guides or bottle bosses if you dont mind lossing your shore lines.

 

[Kent]

Tig brazing is a bit different you want flame brazing right to flow into the sockets right?

I should check out u- tube and some of the older bike books I bet there is loads on it
Obviously not really mountain bike stuff but for repairing old and making retro ideal
My FIL is a bike nut and had a good offer to go pro in France talks about bike building a lot! I just have gotten told all this stuff over the last 30 odd years
Haven't brazed much other than tooling for guys in machine shops and that's mainly gone now
Safe gas welding will teach you operation of the kit