Brazing help?

The small torch you describe isn't hot enough to do an adequate job. You really need oxy-acetylene to braze larger objects. Also need to use a brazing flux to make the brass flow. Common household Borax will do in a pinch. Heat the end of the rod and dip it in the flux before brazing. It is a pretty simple technique; the same as soldering except with a higher temperature. Good luck, Bugs

Too small, not enough heat. Get an O/A rig to do this job.

Jim

All surfaces to be brazed need to be ground or sanded to bare metal. Must be clean! No oil or scale. Also flux must be used. Mix a little powdered flux in water to a thick paste and apply with a small brush where you want your brazing metal to adhere. Thirdly, I don't think your torch is hot enough. I always oxy-acetylene for brazing, never had luck with propane.

Gary Brady Austin, TX

I have managed to silver solder tiny parts with a turbo torch. It took two propane torches to do a part about 1 inch square.

Silver solder melts around 1200F and I think brazing is even higher.

It can be done, but you need to figure out how to insulate the work so you can get the work a little hotter.

You need to have every thing clean and use flux. With propane it will take longer to get hot enough, this means more time for the work to oxidize. To counter that you need more flux.

You are at the limit of doing it. If you have access to a ceramics kiln, you might try that. If you have access to a welder, you might try using a carbon arc to heat things.

Dan

Tom

Propane gets hot enough but it doesn't deliver nearly as much energy as acetylene does.

Brazing is soldering but at higher temperatures.

Can you get by with a soldered joint ?

Try cleaning the area with a strong caustic such as Easy Off oven cleaner to remove oils and greases.

You need to get all three parts (the two parts to be joined and the braze alloy) hot enough at the same time.

Theoretically you can use propane because it gets hot enough. However it delivers the energy so slowly that you lose a great deal. (Theoretically you can move the same load in a pick up truck that you can in a semi. You just make more trips.) You could get fire bricks and try to make a little oven type set up to trap some heat.

Mostly I'll go with the other guys and recommend an oxy acetylene torch. There are an awful lot of these around. If you were to ask enough folks I'm sure someone would know of one.

Tom

Propane will work up to a point.

I've done some larger pieces with the added heat of a Reil burner like you describe. You're probably right on the edge of getting it to a high enough temperature. Try clamping up the big Reil burner to heat the piece overall, and then apply the biggest hand-helf torch (e.g., Turbotorch, yes, a 2nd torch) you can find to the joint.

Also make sure you are using a low-temp alloy brazing rod.

Get a jar of some good commercial brazing flux. It will work better and easier than improvising with borax and such.

Would things improve if I used MAPP gas instead of propane? I hadn't thought about the scale on the plate? Will grind it down to bare metal and look for a lower melting rod, instead of the bronze(?) rod I bought. I do have some insulating kiln bricks that I could make a small furnace to heat the items. I will used my "Monster" Reil type burner to heat the items.

Great info and advice, thanks.

Ron Reil wrote of brazing two cannon balls together with his propane burner, and people use them to melt brass, so brazing is definitely possible with your propane burner.

You need to contain the heat. Try making an enclosure out of fire bricks, or perhaps heating the work in your aluminum melting furnace. Brazing is done at temps somewhat higher than needed to melt aluminum, typically about 1600 deg F. Light red isn't hot enough, gotta be orange. Alloys containing silver work at lower temps (1200 or so, dull red) but are more expensive. You might have better luck with a silver-brazing material.

The problem isn't so much propane vs acetylene as it is air/fuel rather than oxy/fuel . Air is only about 20% oxygen. Your burner needs to flow a lot of air to burn the propane, and that airflow cools both the flame and the work. Oxy/propane works well for brazing but requires an oxy/fuel torch.

As thte others have said, you're not getting hot enough and you need to use flux. Borax is thte flux to use and you can use any borax supply for this. I've used 20 Mule Team brand borax as a cheap source and it works well. For more heat with your equipment, use MAPP gass rather than propane. An O/A torch works better but if you don't have one, the MSPP gas will work. Brazing is a version of soldering and all of the soldering rules apply.

-- Why do penguins walk so far to get to their nesting grounds?

If you want to call we will send you a jar of Black Flux free and some braze alloy. Call Tom or Emily at 800 346-8274. We usually sell this in large lots instead of giving it away but I like your attitude. It's people who won't quit that make a better world.

flux info

Braze alloy info Sand or grind the material down to a rough / gray (smoetimes called ' white' metal) and use a lot of flux. When you are through you still want to see some Black Flux left.

cleaning

For a temperature / color chart go to This is steel under lab conditions and it is just the surface. You want to heat the part all the way through so you will need to get it hotter.

tom

I just found this. It is about carbide but the basics are the same.

Brazing Tungsten Carbide for the First Time

The surface condition of tungsten carbide can make the difference between parts that are joined with a strength of 100,000 psi. and parts that fall off by themselves. You need to make sure the surface is clean and ready for brazing. The best way to determine this is to use a tungsten carbide supplier that can tell you about the surface condition of your parts. Often good tungsten carbide comes ready to braze from the manufacturer. If the parts do not adhere well see the chapter on cleanliness and surface treatment.

Do not get the tungsten carbide oily or greasy. Make sure the steel is clean also. Do not heat either part without a protective flux coating.

Flux Braze alloy joins to metal. Metal oxidizes faster if it is hot. If you heat metal without flux you will form an oxide layer that is similar to rust. Brazing over oxide is like painting over rust. Rarely doe anyone get in trouble using too much flux.

Braze alloy There are many choices. The safest to use is a pretinned tip or trimetal also called plymetal or sandwich. It comes as ribbon. It is flat and has unique properties that relieve stress caused by overheating. It is a tremendous aid when heating large parts or working with a torch. It is more expensive than wire. If you are starting and doing just a few parts this is safer and probably easier.

0.15" (15 thousandths) is about as thick a ribbon as you will need.

Prepare a clean piece of steel. Make sure there are no oils or greases. Alcohol and detergent or soap may both be necessary. Easy Off Oven Cleaner works very well but is dangerous. Remember steel comes oiled to keep it from rusting. An oil layer you cannot see or feel can ruin a braze joint.

Coat the steel with a layer of Black Flux. (Black flux has more Boron than White Flux and works longer at higher temperatures.)

Put down your piece of braze alloy cut to shape and coat with a light layer of flux.

Put the clean tungsten carbide on top of the flux layer and coat the outside with a thick layer of flux.

Hold the part in place with a ceramic rod while brazing.

Heat the whole part as evenly as possible until the whole joint is at the proper temperature. This is usually at least a dark cherry red. Remember that the part has to be hot enough all the way through. This can be a problem even on the parts as small as saw tips.

Once the parts are hot enough you will see the alloy flow out of the joint. You may also feel the part move just a bit as the alloy turns liquid. Once the part is the right color (dark cherry red to cherry red) and the alloy is coming out just a bit (and it may feel mushy), then wiggle the part just a little bit to allow any flux or fumes to escape. If you work the part too hard you can force all the braze alloy out of the joint and ruin it.

The flux cleans off with warm water. You can use mild brushing if you wish to speed the process.

I called and talked with Tom, great guy, very helpful. Tom had sent the package with a #1 can of "Black Flux" and some brazing wire. He even tossed in a really nice coffee mug filled with candy, Nice touch!

I haven't begun to do the brazing project yet, got a hurricane heading my way and need to prepare for the worse. Need to finish up on the modification to my 10Kw generator project, converting from a evap cooling to a thermocooling system.

Thanks Tom.