Diffuse heat from an arc welder?

I asked that question a while ago and was directed to acetylene instead of a carbon rod. Soon after I found a Victor tote kit with a rosebud tip for $50.

Victor is right about it being for "light" duty. I think most people would be better off with a larger set. It's perfect for welding 24 gauge thermocouples, though.

Amazon warns that it's not for children under 3. I was all of 5 when I learned how to make sand molds and cast aluminum.

If I could find an O/A rig for $50 I'd grab it. Those I do see are a couple hundred, plus that much for tanks. It's not something I'd use at lot, so I'm hesitant to spend the money and storage space.

A plasma cutter, on the other hand, would be a whole new capability. If it could be adapted to heating applications without self-destruction there'd be an incentive to experiment. In looking around on the web there aren't a lot of details on how the cutters avoid electrode damage. Probably it's done with gas flow, but no clue how much is required.

I'd be more apt to unstick rusty fasteners.

Thanks for writing,

bob prohaska

My 30A plasma cutter quickly drew down my 1/2 HP air compressor and burned out the tip. I bought a 3HP compressor but haven't needed the plasma cutter again.

I know that you can turn down a tig torch enough for brazing instead of welding. Can you turn it down enough for your purpose? The hot spot would be maybe an inch in diameter but with constant motion you should be able to control things. How diffuse do you need it?

My 40A plasma cutter runs fine off my 2HP compressor but on one job I was asked to do it kept giving up due to excessive voltage drop on the supply. The guys doing the job had multiple extensions and the voltage drop was detected by the plasma cutter as a more modern unit and it faulted and refused to work. The use of heavy duty extension from a nearby socket sorted things and cutting progressed and the job was completed.

I didn't ask the original question, but the answer is that my TIG supposedly goes down to 10A. The lowest setting is too much for me to weld soda cans. I have to turn it up a little to weld 0.025" wall 4130 aircraft tubing.

If you ever need a 260V 100A version of the Kill-A-Watt power meter, look into the PZEM-061.

Jim,

Thanks for the recommendation, one of those may prove useful and cheap enough to buy, some even stocked in the UK rather than China.

I've had pretty good luck with the AC and unipolar DC versions of that family, except that the 20A DC one doesn't like being connected to solar panels overnight. I think the fluctuating low voltage at sunrise or sunset may be putting it into calibration mode with the wrong inputs. A proper calibration fixes it.

The bipolar current, battery capacity meters I bought have almost all failed. The difference is the unipolar meters connect the current shunt to power supply (-), the bipolar ones to the A/D reference voltage and need a separate floating power supply.

A plastic conduit tee makes a good housing for the current shunts.

Diffuse enough to not melt spots on the workpiece, ideally. I've seen the YouTube videos on TIG brazing and agree it's probably worth a try if I get to the point of really needing a non-melting heat source.

One of my handicaps is poor close-in depth perception, getting worse with age. If an O/A torch is backed away from the work it stays lit. An arc, stick or TIG, goes out, within a much tighter range of distance. That makes a chemical torch far more forgiving than a trasferred arc. A non-transferred arc _might_ handle more like a chemical flame and be easier for casual use.

My question is partly just for background. I got curious about plasma cutters and tried to learn how they work from online sources. There's lots of material on what they can do and how to use them, but very little on how they work.

I gather plasma cutters use a tungsten cathode and start with a copper anode, with the gas carrying the arc to the (positive?) workpiece for cutting. The gas blast lifts the arc away from the internal anode, protecting it from erosion.

Could, for example, the internal anode be made of tungsen also, using something like argon or hydrogen for the plasma, at low enough flow to transfer useful amounts of heat without eroding the anode or workpiece?

Thanks for replying,

bob prohaska

Both are new to me, thank you! They strongly emphasize workpiece erosion rather than workpiece heating. Maybe pussyfoot TIG is the first thing to try. Have to practice a lot if that's to work.

Thanks for writing,

bob prohaska

Greetings Bob, I have used TIG for heating metal. I just traverse the torch back and forth so the the arc never sits at one place for long. But if I need to heat more than just a small area or a small piece that I'm about to weld on I just use a torch. Much easier. Another thing you could try is to just ground the torch a little away from the ground clamp and just step on pedal a little. Eric