Welding Tips and Tricks

This will probably seem like an insane idea to many but please bear with me and provide feedback on whether it's realistic or not.

Is it possible to create a big hot knife with a steel plate and an arc welder?

A friend has a slab of salvaged lead in her yard that must weigh at least a thousand pounds. It tough to tell but it probably averages 2 to 3 inches thick and from the top it covers over 10 square feet of area. It is not uniform in thickness, it looks like it was just dumped out of a smelter somehow.

We would like to melt it down for fishing weights but it's too big to handle. We don't want to use any kind of saw because we'd create an environmental nightmare with all the particles that would get strewn everywhere (and she has animals that live in this yard). We've tried wailing on it with an axe and gotten nowhere. It seems like heat is the only solution but it's too heavy to get over any kind of vessel we could melt it into with a weed torch.

I've heard of using an arc welder to safely heat frozen pipes so it got me to thinking maybe we could do something similar to heat a square foot of 1/8" steel enough to turn it into a hot knife that can be driven down into the slab to neatly slice off manageable chunks of material without getting lead everywhere.

But before I'm willing to just connect the ground an stinger of my old Lincoln tombstone to opposite sides of a steel plate to see what happens I figured I'd at least ask some experts about the idea. Am I out of my mind? Or if it's feasible how much current will it take to get the plate just below red hot? Will I only be able to run it like this for very short cycles?

Thanks for your indulgence.

I get what you mean. I think I've seen the thawing device, but I do believe it has an extra machine in the system to limit resistance...? If it was just like stubbing out the electrode, the resistance would just build up until it popped the fuse or breaker, Would it not? I think for you, melting it into section with an oxy torch might be the way to go.

Even melting it with an OA torch causes harmful fumes. Use a quality respirator...

The fumes are obvious and respirator a no brainer, but frankly I'm more concerned about spatter using a torch. I just don't want to liberate tiny lead droplets or particles and have them flying all over her property.

cj737 wrote:Even melting it with an OA torch causes harmful fumes. Use a quality respirator...

The old Lincoln AC 225 welders had a circle around the 75 amp tap.

The literature of the day said it would gently heat the pipes and could be used for an hour continuously before cool down. No additional device needed.

Faster way to heat a plate to red hot would be to use the weed burner.

Liquid lead will still pour from the "cut" however.

Have you tried drilling a series of holes and then breaking off a chunk?
Put a pan under the hole drilling to catch shavings, sweep the top into the pan too.
Drive a wood splitting wedge into the hole drilled line if needed.
I bet it'll break off.

But I'd bring an engine hoist over there, load it on a trailer, and do it at home.

I have no idea if this will work but I would try it:

Get some dunnage under it. 4x4's would probably work. Leave enough room on the edge to make your cut width x 2 and put a plastic tarp under that. Use a Sawzall with a demo blade and soap it up with bar soap to keep the lead from clogging it up and just start whittling away at it. The lead shavings will get captured by the tarp and you can do with them as your please. Even with the soap you'll probably need to stop and wire brush the blade often. I don't think the Sawzall will throw chips out of the area that you want to contain them in if you plan that right.

Lead is soft use an ax!

If your worried about bits when using a cutting torch you could try a rose bud and just heat a large pool then scoop it out with a casting spoon spoon for your fishing weights since it's 2-3" thick you could take a large swathe out of the plate and maybe make it more manageable.

Or heat a line up on the corner till the lead turns into a playdough like state and snap off the corner.


I work with solder pretty much all day everyday. No matter how you go about it your going to get little bits either popping off during heating or falling here and there while cutting with a torch etc.


No matter what I do at work there's always little balls of all sizes all around my solder work station. Specially if im working on a old radiator the older solder and lead is the more it's corroded and the more it tends to 'spit' when heated. One way I've found to help with this issue is slightly heat the solder and use a wire hand brush to scrub the surface clean. Then the solder or lead doesn't have to break through the oxide crust.


Hope I've helped and if you have any other questions feel free to ask me.




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