filbone

Hi guys,

I have successfully built a lugged frame using a MAPP gas torch. Although it's affordable but at the same time very limited to what it can do.

I was told by a work colleague I'm better off using Oxy Propane.

Is this set up good enough or will it produce enough heat to fillet braze?

unterhausen

yes, adding oxygen will help. The little oxygen cannisters they sell at the hardware store are very expensive though.

tuz

Oxy-propane can carry plenty of heat, that's what I use. You would need a few different torch tips/nozzles to make the most of it.

filbone

Oxy Propane sounds very promising. I want to try fillet brazing using this set up. Thanks guys!

Andrew R Stewart 

From what I've read OxPro creates a larger flame without as hot an inner cone, compared to AO). When i fillet I like to use the inner cone to localize the heat while I build up filler. I know others do fillets with OxPro, it would take a relearning curve for me. Andy.

Live Wire 

Just get an oxy/ac setup and be done with it....no more wondering "will this be enough"?

unterhausen

I think oxy/propane is going to be more and more common in the U.S. as the safety laws get more stringent. It's definitely hot enough, it may take some adjustment to work with.

tuz

I don't have a lot of experience with O/A, but in some ways the bigger diffuse flame of O/P is better for lugs, while the sharp cone of O/A is better for filleting. With O/A you can lay a fillet quickly almost like a TIG or gas weld. With O/P you have to stick around the pool a tad longer. But it's a matter of habit, both work fine.

Sixty Fiver

Oxy Propane is more than sufficient for brazing brass and silver and is also less costly.

MassiveD

OP is good, just different. If you use a concentrator, you can get your oxy costs down, otherwise propane is far more oxy greedy, I think something like 6 times. So that part does get spendy. You can weld with OP, so certainly brazing is no problem. If you are used to something else, you would probably have to play with some stuff, but there is a wide world of options out there, just treat it as OP, and don't run your normal process then be surprised if it doesn't work.

Big advantage gas wise is that you get to use a far less dangerous gas than A, which is really an industrial setting type of gas. Many people's vehicles, at least around here, won't even safely/legally transport A. A is like that show 1001 ways to die. Particularly for folks who are not going to get training, OP is less risky. And it is acceptable in a domestic setting. Of course your local rules can be hugely different. OP is also cleaner burning, both for the work, and for the workspace. If I was a pro working in a pro shop space, I would use OA, but as a hobbyist, I have no interest. Mostly I would use OA for the welding, and for the oxy consumption, not anything to do with results.

MassiveD

Not to mention I am retired, on the east side of Toronto. It's a 40 mile round trip in my truck to pick up A, and I probably have to make trips for the oxy also, depending on the rate of use, I'm not going to stockpile gas in my suburban home. Gasoline is 6 bucks a gallon at the moment. Plus up here industrial gas, like A, is about twice the cost it is in the US, with the enviro taxes. If I was working I don't think I could get gas at all outside of bank hours. In BC some retail super stores sell it, but not around here. Plus the bottles are expensive to buy, they are not accepted at different sellers, and two local places have closed down in the last 5 years, so you can end up either traveling even further, or buying new 160 dollar containers.

I can get propane about 300 yards from my home. If I really wanted to get tricky I could run my system on LNG from taping a pipe, and I could use a concentrator for the O2.

Henry III

I have to finish up building my O/P setup. I picked up my oxygen concentrator about two months ago for $200 and a tank of Propane I can find at any gas station or even at Walgreen for about $40 a tank without a trade in and with a trade in it's like $15. Why wouldn't you not want to run a O/P setup? When Trek was still brazing their own frames they were using O/P. So it's not just some penny pinching backyard builders running this setup.

Sixty Fiver

We have a professional shop... have been using OP for 30 years.

This is nice as I cannot handle Acetylene without a decent respirator while OP does not bother me in a well ventilated shop.

unterhausen

was that on ebay?

MassiveD

Local craigs, and kijiji have them all the time. The ultimate motivated seller group. I would say around here, for a low mileage one, they run closer to 300. Occasionally, actual craft ones show up, and they are supposed to be designed to run a slightly higher volume. They go for around 400, and I don't know if they are really worth it.

or

https://www.riogrande.com/Product/EX-...r/500140?pos=1

Henry III

I found it on CL. I'd say there's atleast alway a few on when I look but can really vary in price. The one I picked the guy was selling cheap because his mother passed away and just gave him bad vibes.

GrayJay

From what I have read, oxegen combined with propane through a conventional dual pressure acytelene torch is low efficiency (in terms of the O2 consumption) but if you get setup with an injector style torch which uses venturi vacuum to "pull up" the propane and mixes it better with the O2, then the efficiency is much better. THe only injector torches I see available are fairly heavy-duty welding & cutting torches, anyone know of a lighter duty injector torch more suitable for framebuilding brazing?

MassiveD

Not to play Mr Science which would not be a convincing role for me, but I think the ratio of Oxygen consumption is pretty much fixed by the underlying chemistry. There may be some torches that are a little more efficient than others, but I don't think you can move the markers that much.

"oxy/acetylene burns at a rate of 1.1 parts acetylene to 1 part oxygen by atomic volume, and oxy/propane burns at like 3.8 parts propane to 1 part oxygen." Not really sure what that means when one gets down to the actual weights of gas in the bottle, etc...