Framebuilders - Learning how to braze
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11-12-07, 04:40 PM
My longtime interest in learning how to build frames has been recently rekindled by the destruction of my fixed gear converted Peugeot frame in a collision with a car. I'd like to start by trying to build a decent/nice track bike first. I know where to acquire the parts and I understand the basics of frame geometry and design. However, I have no experience working with welding equipment. I think I'm going to take a class on the subject at my local technical college, but am not sure which one to take. I know that you can't guess what will be taught and what will not, but how does this sound for getting introductory knowledge on the subject?:
"Fundamentals of Oxyfuel Welding: Students develop a fundamental understanding and skill in the use of oxyacetylene welding equipment, including safe handling of cylinders of oxygen and acetylene. Such typical operations as joint design and various types of welds are performed with mild steel filler rod. Some instruction is given in manual oxyacetylene cutting of mild steel. Introduction to basic metallurgy for welders is given."
There is another one which costs less and meets less frequently.:
"Oxyfuel Welding Processes: Safe working habits in handling oxyfuel and gas tungsten arc equipment are developed. The principles for applying oxyfuel on different types and sizes of materials in various joint configurations are stressed. Commercial production, handling and storage of compressed gases that are used in GTA and oxyfuel processes are discussed. Introduction to metallurgy is given."
I don't think I need to know gas tungsten arc welding, but in the description they make the second one sound more like there would be more hands-on practice and with more materials, whereas the first one is going to involve more use of steel filler rod. They also offer fundamentals of TIG welding, which I may eventually take, if my adventure into the world of lugged steel goes well.
I'm aware that it's silly to be asking people on the internet what class I should take. I'll probably end up having to try and get ahold of the instructors and ask them personally what they suggest. I'd like the input from you guys though, and I'd also like to hear where others learned to use welding equipment and why.
I would probably go with the second one, but neither sounds like it is going to hit the nail on the head exactly. The main issue is you will get the knowledge required to work with the gassses, and to light a torch. Everything else sounds like it will be more directed towards stuff like cutting up old factories. Actually I am a little surprised to hear anyone is teaching gas welding at all. Hey if they are cheap or free, it would likely be time well spent. Around here they dončt seem to offer the trade type evening course any more.
If you want to learn this kind of stuff, I would go to smartflix, and rent the Paternek videos on lug and fillet brazing (they are designed so that regardless your prefered process there is lots to learn from either DVD set). get the 4130 gas welding DVD set, and maybe the Ron Coville TIG set if you like. I have seen his welding elsewhere, but not that tape set. The 4130 set is gas welding thin wall tubes just as with bikes. Even if you dončt do that, it will cover the right size of torch extensively.
11-13-07, 08:11 PM
You may well know this, but I'll spell it out for those who may not. Gas welding isn't brazing. I learned gas welding first myself. But the big difference is that the base metal isn't melted in brazing. Gas welding is much like TIG physically speaking--heat source in one hand and filler in the other. AFIK gas welding is never used in modern framebuilding, but brazing-with or without lugs, and TIG (GTAW for the young folk) is.
That being said, I do like and use gas welding for non-frame stuff, but that's mainly because I don't have a TIG machine.
I'd look for an intro to oxy-acetylene-which should cover torch and cylinder handling basics (safety) as well as brazing, welding, and cutting.
But any torch time is good torch time, so take what you can get.
sparky sparky POOF
11-14-07, 01:17 PM
Thanks for the responses.
I was expecting to read what you guys wrote. It sounds like learning the basics of firing up the equipment and heating stuff up are pretty simple, and that it's mainly practice with oxyacetylene, tubes, and lugs.
Milwaukee is a pretty industrial town, with at least a couple frame builders (Milwaukee Bicycles is one), and a few established bike shops, so I imagine I can find some sort of bike-specific training. I'll post again if I find anything relevant here in town.
I've never heard of anyone gas welding a frame, unless you are taking about 500 000 aircraft during WWII, and thereafter until about 1990, and to this day in the amateur market. So there isn't any reason why one shouldn't gas weld a bike frame. There is some evidence/suggestion/preference that it is superior to tig, though superior to good enough isn't really a big advantage. For the same kind of reasons brazing is prefered less high end heat, if for a longer time. The 4130 tapes go into all this stuff.
One big problem for the pro is that gas welded tubes don't look like what Don Feris pumps out. They look kinda cruddy from what I have seen. However there are ways around that. It's also slow in a production setting.
It's also possible to weld aluminum tubes with gas, and there the advantages seem a lot clearer. It seems a lot easier, with less problems in the weld which is why even some TIG guys like Jesse James, have fooled with it when TIG gave them porosity, poor fab, and poor finishing. Though I'm not sure he stuck with it, he uses everything. It's just an example of how people with every tool to choose from do use gas welding in very delicate situations out of preference.
I don't really care who is right, I just expect to be able to extend the range of what I can get done with my non-ac tig.
11-28-07, 05:10 AM
+1 on recognising the need to attend a course of instruction and attain a level of competency before building a frame.
You need a course that will teach you brazing and braze welding techniques, the first course sounds like a good start as the tip and pool control you learn oxy welding you carry on to all welding, the other course sounds like safety training for production operators.
I suggest giving them a call and discuss the courses before committing.
11-28-07, 07:58 AM
I would recommend that you take a course at the local welding supply store. This will be much cheaper and you get to try out the latest and greatest equipment. I think that you will find that TIG welding is the best as it can be used on any metal. Gas welding is not suitable for bikes due to the concentrated heat fatigue. Don't get me wrong, you can certily join 2 pieces of steel together with gas welding it is not the best method. TIG is clean and almost artistic if done correctly. You local supplier will even rent you a welder so you can play at home. I rented a TIG to build a swim platform for $110 per week. This would have been credited back if I purchased a TIG welder. I don't know if you have HAUN or Airgas in your area. Check it out.
11-28-07, 10:02 AM
While not the easiest way to do it, bike frames are gas welded all the time. Check out the cool stuff at
http://www.thursdaybicycles.com/ for a few examples.
11-29-07, 09:18 PM
i re raked my headtube on my flatland bmx. bringing from 75 to 73.5, i did this by gas welding the 4130 tubing. 100's of hours and everything is fine, although, 2 weeks after this welding, i was in a "hang 5" and the front gave on me, in my mind as i was falling i thought it was the headtube rake id done without question, however, when i picked myself up, to my bitter sweet avail, were my 5 month old 7000 series Al forks broke cleanly in half.
im going to ask on this thread before posting. what size tip is suitable for brazing this thin wall stuff chromo?. i've brazed way long ago, and it was hot, nearly melting the base i remember. yesterday at work i was making some collets for a weight set, went to use the oxy with a large tip, and ran the flame in a "carby" setting to keep the heat low, and when i applied it even slightly near the stainless, it melted away, it made me realize how much the SZIE of the tip can effect the power of the heat.
11-30-07, 06:10 AM
The temperature IMO has more to do with the gas mix and pressure when brazing than tip size. If the work is getting too hot, reduce pressures and/or move the torch farther away
I normally use MAPP for silver brazing lugs. For fillet brazing I do use O/A. For thin steel tubings (<.035" or .9mm) I use a #63 drill size tip (Smith AW204 on my rig)) most of the time I set the regulators pressure to 6/6 psig at room temperature and adjust from there.
"are gas welded all the time." Possibly only if Thursday is working around the clock. He refers to it as "the forgoten art". Great reference though, good to hear someone else is also crazy enough to do it. :) It has the advantage of really keeping the costs down, you don't need a TIG, and can do brazing and braze ons with the same torch.
12-09-07, 08:44 AM
See if you can talk to the instructers before you sign up. Most of them are very experienced and have probably done some brazing - maybe even quite a lot. They would let you know if the course they are teaching could accomodate some separate brazing instruction, and if not where you could get brazing instruction. In our area (Northeast WI) there is a great demand for welders, especially GATW (TIG) welders, so most of the courses fill up early and focus on welding, not brazing.
12-09-07, 02:13 PM
Take the class which has the most time you can 'afford'. The real cost of the class is how much time you can devote to the subject, not the tuition. From my experience, brazing is not difficult. I can braze well. If someone can solder, they can braze.
Welding is a completely different technology. Welding takes skill. I can weld with a gas torch, but not well. If there is someone who can teach you how to gas weld steel, and you have the opportunity to learn from them. Take it!
12-11-07, 02:12 AM
I didn't want to start a new thread for this question, but I've done silver soldering on brass and copper, and was wondering just how similar it is to brazing in practice. I know that brazing is done at a higher temp. but if I'm familiar with soldering tubes and pipes, would brazing a frame be a really big jump?
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