well i am going to put a magura on my muni (which need brazing on). obviously i could take it to a shop/garage and get it done but i saw in halfords i can get a Bernz o matic brazer (it also cuts, welds etc) from halfords for £40.
so i would be able to mount it myself and also have the brazer for future frame designing/general use.
i was just wondering does anyone know how hard/easy it is to braze?
i have got some old metal to practise on before i try to mount the magura.
I’ve done a fair bit a brazing, mostly using Oxy-Aceteline. A propane torch should braze OK but it wont pump out the heat very quickly so you might end up warming up more metal than you’d like. I’ve not tried with just propane so I’m not 100% sure how well it’d go.
As for brazing up a whole frame, of course you can. All bikes were made this was until welding started to take over in the 90s. If you use thin walled tubing (which you will) then the brazed joint will probably be the strongest point. It’s a great manufacture technique for unicycle frames.
I’ve got a book about brazing that you are welcome to borrow if you are passing through Roath.
I started at college. It didn’t take at all long to learn. It was a convenient way to make stuff as I couldn’t weld. i’ve since got a lot better at welding so brazing has got a bit relagated. I been meaning to a bit more as it a nice manufacturing technique. TIG welding aluminium is next on my list if thing to learn, though.
With welding there is a huge difference in the quality of the welding kit. It’s not just a bad workman blaming his tools. The cheap (>£150) machines make welding really hard, and a decent (>£500) machine makes it so easy. I don’t think the same is true of Oxy Acet as most of the cost is the bottles and gas.
I have done quite a bit of brazing and am self taught I wanted at first to put a set of brakes on a sem xl unicycle and then started building my own unicycle , I have since built six unicycles. I am puting in apicture of four of the unicycles I have built the red one with the magura brakes is mine the others I have built for friends. I start with a mountain bike fork that I have removed the brake mounts and with heat I bend the fork straight then braze on the united bearing holders, then with an oval steel bar and a hammer I pound out more tire clearance also using heat, then I braze the brake mounts back on for a 24" rim. The brazing takes some practice and the metal needs to be clean and you need to use flux, but with a little practice you should do fine, the best would be if you can watch someone else do it to get your flame adjustments corect. good luck, Dan wilson
We are both thinking the same thing, I also went to Halfords this week and have been hammering Google about Brazing for a couple of weeks.
The torch in Halfords is an Oxy-Propane, not aceteline, although not as hot it should be able to Braze.
On the Bernzomatic website this appears to be their only oxy-propane torch the rest are propane only.
One issue is the cost of oxygen cyclinders for these type of torches on the welding forums, you only get ~15minutes for £7! One person reckoned he used the cylinder just getting the flame correct, others state you can build 1 bike frame per cylinder. A lot of people replied on the forums that they soon switched from one of these torches to a full oxy-acetelene setup.
My plan is to buy the chromoly tubing and get that ready first, then either buy the torch or have a word to the two people I know who have oxy-acetelene setups at home!
Incidently it was the brazed Coker frame which Roger brought to Kidderminster that got me motivated to get on with this project which has been in my mind for months.
Oxy-propane will be plenty hot for brazing and it’s cheaper, you will need bigger cyclinders though, especialy as a beginner. Are the cyclinders you are talking about disposable because that sounds kind of expensive on the other hand if you aren’t going to do much brazing you might not want to buy refillable cyclinders as they are expensive I think mine cost about $250 for the oxygen and $200 for the aceteline but I get at least three hours for about $25. Dan
I am an HVAC mechanic that has done a lot of brazing. I use just an acetylene tank and Turbo Torch air acetylene tips. The tips are designed to pull in air and mix it with the acetylene to make a very hot flame. Acetylene tanks come in two sizes MC and B. The MC tank in the USA is $65.00 and the B tank is around $100.00 the difference is the size of the tank.
The main trick to brazing is to get the metal hot enough that the brazing rod melts on contact with the metal. You don’t want to melt the brazing rod with the torch.
I’ve made two frames to date, both of them mig welded and made from mild steel. i’ve been thinking lately that i want to make an alluminium frame, but i can’t tig weld well enough and don’t have access to a tig welder anymore:( .
the only part of my frame that needs to be welded will be the connection between bearing holders and frame. so my question is, is it possible to braze alluminium? or is the process too hot?
I had another read through my brazing book at the weekend. There is a whole load in there about making you own kit. My favourite was a regular propane plumbers torch with a vacuum cleaner plumbed into to it to give extra air (and heat)
You can join aluminum (the book suggests the best filler alloys) but I think you’d want to make a socket joint rather just a fillet. You can also mig weld or stick weld aluminium but you need a pretty good welder.
You brought back a memory of my dad brazing my broken bicycle frame back together when I was a kid. He was no pro, just using the little tanks, but I remember it didn’t break again. And so now those creative wheels are turning. Wouldn’t it be cool if a bunch of us start turning out and bringing our own frames places we meet? On the other hand, those $40 Nimbus frames sure are a bargain!
well earlier this week i did try brazing and i found it really easy.
i bought the kit (oxy-propane torch) from halfords and i was ready to go.
to fit the magura i didnt buy the braze on fittings (as they were £20) rather i cut some canti studs off an old bi*e (to fit the magura evolution adaptor to).
i used a coat hanger to hold the stud in place, after carefully positioning the stud by bending the coat hanger.
heated it up, applied the rod and it was a success!!!
i cant wait to try my next project (whatever it may be as i havent anything planned as of yet)
so i would definately give it a go if anyone else out there fancies it.
While researching my braking options, I was told that in order to braze brake bosses on my uni frame I would have to strip all the chrome from the frame first. The guys I talked to said they didn’t know of any chromers on the island, so the frame would have to powder coated. All this would cost a whole lot more then ordering a frame from Darren with bosses already on (around $100).
Was the people I talked to correct about the chrome removal? And do any of you know of any chromers on this island (Oahu)?
You can braze onto chrome with hard silver solder (I just did that with a Yuni frme, to fit a larger seat tube on it). The chrome will discolor, so maybe that is what the issue was. I painted over mine, and ideally should have sand-blasted the chrome off so that the paint will stick better. We’ll see how it wears.
Well Keith it says on the bottle that the oxygen should last for approx 15-20 mins from a full can (£~6) i would say it took me all in all 8 mins to do both joints so i used approximately half.
the first time i lit the torch it took me about 4 mins to get the correct flame though but i have got the hang of it now and takes me seconds.
the actual fuel (propane) it says should last for approx 40x longer than the oxygen so that should last for a whopping 10-13hrs so there is loads of this left.
the project was good fun and i got a lot of satisfaction from actually doing it myself
