Looking for advice on what type of gas brazing outfit to get

Date 02-19-2009 04:01

The air/acetylene setup will not get hot enough to braze anything but the smallest parts.

You could just get a high pressure oxy tank & regulator for the set You have now.

If You buy a complete Oxy/Acetylene setup, it will probably come with a cutting attachment. Even if You don't cut anything, You might use the preheat flames from the cutting tip for heating, if You don't have a rosebud.

There are some fair quality import torch sets at reasonable prices, but If You go that route, buy from Your local welding suply company incase You need waranty service.

Victor, Harris, Smith, Airco/Concoa, Purox/Prestolite/Oxweld, are all good products If You want "the real McCoy" There are other companies that made good gear but havn't survived the modern economy.

The limiting factor of a set with small tanks is that You shouldn't draw heavily from a small acetylene tank for an extended period. This is the 1/7 rule, the acetylene flow in CFH shouldn't be more than 1/7 the tank capacity in cubic feet. An "MC" size tank is 10 CuFt, while a "B" tank is 40 CuFt. The next size up is 75 CuFt.

By Maineman (*)

Date 02-19-2009 18:07

Thanks for the advice. I do need to weld or braze steel so that what I repair is structurally sound. Not sure what the difference is between brazing and welding with gas, just need a strong joint. Brazed a neighbor's broken snow-blower handle back together. The other handle is on its way out too so may braze that side as well. Because of the torque on the handles I may need to braze a cross brace onto the handles this summer.

What I have now is a Bernzomatic Oxy/MAPP gas set with 16 oz. tanks. Am told they are 1 CF. Couldn't find a way to add a photo to this web site. It works well for my needs but the oxy runs out in 10 min. Maybe I'm using too much oxygen. The cheapest solution to fit my needs would be to add a 10 CF MC tank with a regulator as suggested and get it filled with Oxygen. Problem is how do I do it? The hose I have is most likely 1/8". Think the regulator would require a ¼" hose, unless there are 1/8" outlets on regulators. If needed, an in-line connector/reducer from ¼" to 1/8" should work. Just want to make sure there are no leaks. Any problems with doing that?

Have seen the small Oxygen/Acetylene sets with the MC and R tanks made by Victor, Harris, Smith, Airco/Concoa, Purox/Prestolite/Oxweld. New they range from $300 to $600 with Victor being the most expensive. Maybe I should just spend the money and get a decent used set in the $175 range. Any thoughts.

Thanks,

Tom

By DaveBoyer (*****)

Date 02-20-2009 02:57

The 10 CuFt "MC" tank is only for accetylene, You need a high pressure tank for oxy. I think there is more usable fuel in a disposable MAPP cylinder than in a "MC" tank. I know what Your setup is like, I got one for $1 at a pawn shop, never used it due to the oxy cylinder cost issues You are having. I have one of those "MC" & 20 CuFt portable torch kits, it is great where You need to carry to a small job, like brazing HVAC tubing. I paid $135 at a pawn shop, that was an exceptional deal, it was hardly used.

The standard hose size for these units is 3/16 inside diameter, they have either "A" 3/8-24 or "B" 9/16-18 fittings. It might be dificult to adapt the diderent sizes of the setup You have.

Gas welding involves actually melting the steel base metal. It is easy to learn, but works best with acetylene, due to the reducing nature of the flame.

You can chose brazing alloys that are as strong or stronger than mild steel, so if You do Your part, a brazed joint can be as strong as a welded joint.

In the long haul You are better with the name brand oxy/acetylene set. If You can afford it, You won't regret it.

By Maineman (*)

Date 02-21-2009 01:50

Thanks Dave,

Think I'll bite the bullet and get a medium duty oxy/acet set with MC and R tanks. After you explaned the difference between a welded and a brazed joint I realized I welded the snow-blower handles together. I'm not that good at it so figure having equipment that allows me to weld would help me get a structurally sound joint and not have to depeng on a well done brazed joint.

Two questions, what is a rosebud used to pre-heat? The 1/7 rule means the flow of gas from an MC-10 CF acetylene tank should be no more than 1.43 CFM, flow from an R-20 CF oxygen tank should be no more that 2.86 CFM. Plan to get a book and take an adult ed course on gas welding in the fall.

Thanks,

Tom

By DaveBoyer (*****)

Date 02-21-2009 03:43

The 1/7 rule doesn't apply to the oxygen tank, it ONLY applies to acetylene, due to the gas being disolved in acetone, much like the CO2 is disolved in soda water. You KNOW what can happen if You open soda water too fast, the acetone can do the same if You over draw the acetylene cylinder. You can excede the 1/7 rule somewhat for brief periods, but you are not supposed too...

Welding will probably work better with acetylene than MAPP due to the reducing nature of the acetylene flame. This is My guess, I never tried welding with MAPP & don't know anybody who has, but I know Oxy/Propane is dificult to weld with.

A rosebud is a heating tip that has multiple flames, this spreads the heat out more than using a welding tip for heating things that You want to heat over a larger area without melting any spots. Only the most tiny rosebuds will work on the "MC" cylinder. Mine is only about 1/4" diameter over the outside with 6 tiny holes.

The cours is well worth it, for the safety issues as well as the welding/brazing part.

I have a Victor portable setup. It came with a 100 series torch, which is a nice enough torch, but it can take much bigger tips than the small tanks can feed. The cutting atachment didn't fit well in the storage compartment either. I recently changed the torch to an old Prestolite W200 that was My grandfathers, I have a better selection of brazing tips for it, and the cutting atachment fits in the storage compartment. There are probably as many sentimental reasons for this change as any other, but it is a sweet little torch.