Propane-Air brazing torches

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Propane-Air brazing torches

Post by SL Ethel » Sun Jun 04, 2017 8:29 pm

I am looking to purchase a propane-air torch for brazing, but I'm having trouble making useful comparisons based on the on-line data available. I'm looking for something cheaper to run and less complicated than a full oxy setup. I'm hoping to braze copper tube up to 4" to make small boilers the myriad other items that one can handily stick together with silver solder.

Anybody have suggestions for what you've had work well for similar service? I'm looking at Sievert, Turbotorch (Victor), and Goss equipment.

Thanks in advance,

Scott
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Re: Propane-Air brazing torches

Post by DetroiTug » Sun Jun 04, 2017 9:38 pm

Hi Scott,

Not sure on the torches. A lower heat silver solder really helps out for small projects. Here is a product I've used quite a bit and I cannot say enough good about it. It will silver solder stainless to steel etc, even cast iron. It's called SSF-6 from Muggyweld. 1150 degrees F flow and 71,000 psi strength. I have no affiliation with them, just a very satisfied customer. Large Copper and bronze will probably need OXY/ACET as they both draw heat away from the work area quickly.

http://www.amazon.com/Muggy-Weld-Silver ... B016U12F6E

When I was a kid I had a "solid-ox" torch. That little thing would cut through sheet steel, braze etc., but it was a bit difficult to control. I don't think they sell those anymore.

If you plan on doing the steam hobby, I would use the funds intended for an alternative and just spring for the Oxy/Acet setup. You'll be glad you did.

-Ron
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Re: Propane-Air brazing torches

Post by Lopez Mike » Mon Jun 05, 2017 3:33 am

Yes to what Ron is saying.

Keep in mind that to do any soldering or brazing on anything as massive as a 4" copper tube will take some effort to keep the heat in the tube. Like a salt box or vermiculite to insulate the parts of the tube that are not being worked on from the air.

Copper is really hard to get hot enough for good work. Conducts heat way too well.
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Re: Propane-Air brazing torches

Post by fredrosse » Mon Jun 05, 2017 5:23 am

The large propane fired weed burners you find at Home Depot, or Harbor Freight, are more than enough for any copper boiler - silver solder job you are considering. I have seen similar size air-natural gas, and air-propane torches used to silver solder copper boilers ranging to about 6 inches diameter x about 3 feet long. The weed burner can get the whole assembly to red heat.
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Re: Propane-Air brazing torches

Post by Lopez Mike » Mon Jun 05, 2017 5:31 am

Very good idea.

I have been using an antiquated gasoline powered plumber's torch for years. I have had terrible results trying to use an Oxy/Acetylene torch as the heat is way too concentrated. Either blows the molten puddle around or melts a hole in things or don't get the whole area hot enough and several other disasters I've forgotten about.
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Re: Propane-Air brazing torches

Post by DetroiTug » Mon Jun 05, 2017 1:20 pm

My experience with it: Propane can heat the material sufficiently, but it's too slow. Heating the whole object during a soldering operation risks damaging joints that aren't being worked, especially with lead solder. That is the big advantage soldering with the much higher heat oxy/acet torch, can heat up the local area quickly and flow the filler before the rest of the part is equally as hot. I've tried using a propane torch to solder up a car radiator, started with one leak and wound up with several leaks :lol:

Problems like blowing puddles away and making holes are signs too much heat, no, way too much heat/oxygen is being used:) Harris sells a complete kit, same one I've been using for about 40 years, for 88 dollars and free shipping on Ebay. I have better torches now, but still use the old regulators and the hoses were replaced. Then get some tanks from the local weld supply, small ones aren't that expensive, but it's cheaper by volume to refill the larger ones. About $250 for the whole set up. One of the most useful things a person can own. Can cut steel, weld steel, braze, solder, very versatile.

http://www.ebay.com/itm/Oxygen-Acetylen ... Swi0RXxHRD

-Ron
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Re: Propane-Air brazing torches

Post by Lopez Mike » Mon Jun 05, 2017 3:39 pm

It is an acquired skill. One that I seem to lack. Also I am red/green color blond and I suspect that being able to see faint reds may help in controlling the local heat. I'm a very poor stick welder. MiG has saved my bacon. Forget the arc and melt the end off the wire!

Part of the trick is to know your limitations. I never do any welding on pressure vessels beyond tacking things together so I can get the wheel thing to a real welder.

I've had so many failures when doing anything but electrical soldering that if I have to solder/braze any copper based structures I try to furnace braze the whole thing at once.
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Re: Propane-Air brazing torches

Post by DetroiTug » Mon Jun 05, 2017 4:29 pm

Furnace brazing is something I've always wanted to learn. I've read up on it and know about the staking, clearances etc, I've just never understood how they did it so well a hundred years ago. I build and rebuild these little steam carriage chassis and have had to get the old tubing out of the joints. Usually involves putting it the lathe or mill and boring it out. Some of these joints are 1-1/2 OD/ID and 3 or 4 inches long. There are no voids in the joint at all, the bronze pulled all the way through. I can't figure out how they did it - added that much filler material and have it flow correctly and completely in a furnace.

-Ron
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Re: Propane-Air brazing torches

Post by Mike Rometer » Mon Jun 05, 2017 5:11 pm

75 The Boiler Inspector Seems Pleased (600 x 393).jpg
75 The Boiler Inspector Seems Pleased (600 x 393).jpg (61.79 KiB) Viewed 8807 times
I made this boiler with two large (Sievert) propane torches. It weighs in at about 1.25 cwt. The secret is to keep the bit you don't want to heat, covered, with either fire brick, or blanket, or both. Both torches are used to get the temp up, the solder feeder then concentrates on the joint while the mate keeps the surrounding area heated.

The biggest problem was differential contraction, so when the joint was finished the whole thing was covered and left. One time it was still warm to the touch 2 DAYS later.

Sorry about the quality of the pic, it's a scanned colour print.
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Re: Propane-Air brazing torches

Post by Lopez Mike » Mon Jun 05, 2017 6:00 pm

I read an article about old (1920's) motorcycle frames. They made sure that there was about one or two thou of clearance by making little raised craters with a center punch, fluxed the joint and, when using a torch, heated the other end from where they were applying the filler and it seemed always wick through.

It was an education when I first watched a pro plumber do copper. Fast and no bad ones.
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