Kevin is shooting an infrared thermometer at a piece of 1/4″ plate on his workbench. The workbench is at 56 degrees Farenheit, the metal at 57.

Have you ever started to MIG weld a piece of metal and get a blob of metal at the beginning? The weld doesn’t want to penetrate. It looks awful. You’ve got to come back, grind it off, and fix it.

That’s because your metal’s cold.

Kevin puts on his safety equipment to show you what happens – and how to fix that problem.

He’s using the Everlast Lightning MTS 275. It’s already set on MIG steel, C25. Kevin uses PowerSet for a quick set up: .030 on the wire; material thickness 1/2″ plate; 350 on the wire; 21.9 on the volts. Says Kevin: “Let’s spark it up!”

After welding, he’s not too crazy about the way the PowerSet worked – he’d change that a bit for the next weld. Still, you can see how the first part of the weld is raised, then it starts to flatten out. And that’s just from the metal being cold, that 1/4″ steel plate sitting on that 1″ workbench tabletop, which sucks all the heat out of it. You’ve got to get that metal up to temperature as you’re welding.

Kevin cools the metal back to 56 degrees so he can show you a trick.

He doesn’t change the welder settings, and the metal is again clamped down on that cold 1″ workbench. But he grabs a propane torch to preheat the area he’s going to weld.

As he warms the metal, Kevin notes that, if you were using 1/2″ or 3/4″ metal plate, you wouldn’t be using a propane torch. You’d need to use oxygen-acetylene and a rosebud for greater heat. As he heats the metal, Kevin shows the moisture moving out of the steel. When the temperature hits 220 degrees, he’s ready to weld it.

After the second weld, Kevin shows both welds. You can see the initial “bump” on the cold weld and how it flattened out as the metal warmed up. The preheated weld looked much flatter with better penetration.

Kevin acknowledges that preheating requires getting out a torch and preheating when all you really want to do is grab your welder and get the job done. But it really does make a difference.

And, of course, there’s a way to cheat. Just take some pieces of stock and raise your metal off the table. That’ll help concentrate the heat from your welder in the metal you’re welding rather than having the workbench suck up a bunch of it.

Preheating can also help if your welder isn’t big enough to weld thicker metal. You can preheat the metal, which will give you better penetration.

Thanks for watching – hit the YouTube notification bell to be the first to know when he releases a new video.

Before you go, though, stick around for a second to see him share an origin story ….

See this video now ….