Confining heat

Old 01-21-05, 12:28 PM
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Question Help! It's getting too hot on such a little spot

OK, welding geniuses, using oxy-acetylene, I am welding pieces of 1/8" and 3/32" welding rod together (to make decorative frames). The PROBLEM is in keeping the burn area to a minimum. Too much of the copper coating surrounding the weld is getting burned off ruining the finish.

Using a larger tip (202 rather than the 203 I use for brazing) I seem to be able to get in and out quicker and this seems to help a little but results are inconsistent and often the burn area is still too big.

If you were to take a piece of 1/8 welding rod and a piece of piece 3/32" welding rod (copper coated mild steel) and bend them into round shapes then set them side by side, flat on the table and spot welded at the one place where they touch...well, this is what I am doing. I am using 1/16" welding rod...this has no flux. I need to keep the burned area to a minimum... ideally no more than 1/4 inch on each side.

Would a flame that is on either side of neutral be to my advantage? Should I try larger tip, cooler, less focused flame, or smaller tip and a hotter more focused flame? I can't yet completely distinguish between the neutral, carburizing or oxidizing flames.

I've tried different tips and air gas mixes but it's been hit or miss. Sometimes I achieve my goal and sometimes the wire gets too burned up.

Last edited by chavella; 01-21-05 at 01:10 PM. Reason: clarity of title
Old 01-21-05, 08:49 PM
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Are you certain that OA welding is the right process?

How much load does the joint have to support?

Heat processes: brazing, silver soldering and soft soldering

Cold processes: two-part epoxy

For as small a thermal mass as you are joining, consider an air-propane or oxy-propane heat source and a solder with acid flux or silver solder and the appropriate flux.

When starting adjacent joints, use heat sinks if needed to prevent the heat from the new joint undoing the adjacent joints.

Sweating copper pipe with an ordinary propane torch and acid-fluxed solder holds very well, though the contact area is much larger.
Old 01-22-05, 07:16 AM
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Some of my welds are actually brass soldered (brazed) using no flux. Works well but joint needs then to be buffed to achieve the "look". But for the other, I want the black weld mark...just not such a large one.

Can I weld two pieces of 1/8" rod using 1/16" rod with oxy-propane?
Would I be able to confine the weld to a very small area?
How safe is propane to weld with?

Using flux isn't an option for my work.

Old 01-29-05, 10:53 PM
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low heat

For what you want, I think a small 110V mig welder with gas along with a soup can full of water for instant cooling would do just what you want.
Mike A

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