Hi all
I'd like to be able to braze a bicycle frame. Oxy acetylene is too expensive for occasional use so what are my alternatives? Limited research suggests MAPP, Propane or natural gas could be used as fuel but will I be able to use air rather than oxygen?
Anyone got and peronal experience?
Thanks
Propane-air would just about do brazing, but if the heating is too slow you might melt out more joint than you make. If the frame is 531 or better (753 etc.) then don't even try!
Personally I'd pop it round to a local engineering firm and part with a few beer tokens to have it brazed properly. Last thing you want is part of the frame parting company at speed.
What do you mean braze a bicycle frame?
The whole thing from bare tubes and lugs? a brake cable stop? a bottle cage insert? a dropout? a frame stay?
Many years ago I've used a couple of butane torches for small fitting repair jobs - not true brazing though as I used silver solder. Propane-air ought to be up to the job but I've no firsthand experience of it.
It might be useful to read the Tim Paterek manual on framebuilding - the old version which is still crammed full of useful info is now free, the new one is $75, and even then its much better value than Richard Talbot's 'definitive' book on framebuilding which often commands stratospheric prices - amazon has it for 212 quid secondhand!
Yes, the whole thing from bare tubes and lugs. I have considered the Dave Yates frame building course but when you include all the costs, including a week's accommodation, it's pretty expensive.
Option 2 is to have a go myself, option 3 is to have it made by a local frame builder (about as expensive as the Dave Yates way) and option 4 is to have it made in titanium in China by XACD.
Thanks, I've done a bit of reading and have been searching for a cheaper copy of Talbot's book for a while.
To braze a complete bike frame, you have little choice but to use oxy-acetylene (or electric TIG). Mapp gas torches, with their air/oxygen cylinders will be expensive for such use, plus, Mapp gas doesnt get hot enough IMO, you spend 10 minutes or so warming up the tubes before you can think of brazing. When I used it many years ago, the oxygen cylinder would last at most 20 minutes. Took 2 cylinders of oxy to weld a ~6" square plate on my car. It has ben sat in the garage since - just too expensive to use.
Alan.
If you are asking about brazing, you can only be using steel tubes. Aluminium will be too soft for a bike frame. Personally, I would go for the Chinese titanium frame. Having worked with this metal for some time, you will be amazed at how light and strong it is. Just don't plan on giving the frame any crash shocks. It won't recover. On the other hand, steel tubes can sometimes be re formed again.
It will probably be as strong as braze as the joint is in sheer. But the possibility of having a titanium frame will bring down the weight of the cycle considerably.
Dave
An ex biker of old
Err, ITYF that the vast majority of decent quality bikes are aluminium framed. Alan.
Wont aluminium be soft after brazing?
Dave
TIG welded. Probably heat treated as well after welding. Loads of differing grades of ally, just like steel - 531/753/853 etc. Alan.
It wont braze without special fluxes anyway.
Dave Yates told me about all the courses he had to attend for these alloys. Not a lot of tolerance in 753 and 853 - easy to bork.
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