VIDEO: How to Clean Metal Before MIG Welding

In this video, I want to explain to you how I clean metal for the best possible mig welds

Now as I've mentioned before in other videos, strictly speaking, you don't need to get back to bare metal in order for a meg weld to work

But for it to work to its full potential and for the bead to look as nice as possible and be as strong as possible, you do need to get back to bare metal

This is a piece of black iron pipe. It's called black iron because it's black on the surface

the actual metal isn't really black. What you're seeing on the surface here is something called mill scale. So you can imagine this started off as molten steel and it was extruded. Actually, this is this is welded pipe. I don't know if you can see that, but there's a there's a weld bead in there. So it actually started off as some flat stock and it was it was bent in a factory and welded. And it seamlessly welded. You can't really see the weld on this

this side. But during that process of heating and forming and manufacturing, there's a kind of

with a mill scale forms on the surface It a product of oxygen and I guess manufacturing oils and pressures and all kinds of things And that why this is black Now it starting to rust a little bit here too because it been outside

Bottom line is that we want fresh clean steel if we can for the best possible wells

And the usual tool for that is something like this. An angle grinder with what's called a flap wheel, which is an abrasive

It removes a fair amount of metal. It does it fairly quickly in most cases

But it's not the best for this sort of thing, because it actually travels so quickly

The maximum RPM on this disc is over 12,000. I think it probably spins at a full 10,000

I don't know if it says anywhere here. Yes, sorry, 8500. So it's really spinning very quickly and so quickly, in fact

that it can actually burnish the surface of the metal. and not remove the mill scale as fast as you might like or as you can

What I have found works better than that, and it's nicer to use to

It's more controllable and it's more effective and that's a regular woodworking sander

This is a five random morbid sander As I said it meant for working with wood but it happens to do a great job getting off this mill scale So I going to show you that but before I do I just want to point out a couple of different abrasives

This is the sort of abrasive disc that's sold most commonly for use on a 5 inch random orbit sander

Works great on wood, and it works pretty good on metal too

But what works better on metal is this mesh-style abrasive. So you can see my fingers through it, I think

And the advantage there is that there's, well, the advantage for woodworking is that there's all kinds of holes in here

And sanders like this have a built-in vacuum system, a little vacuum system

These holes suck the dust in, trap it in this canister. So something like this maximizes

the airflow and the sawdust pickup when you're dealing with wood. But what I have found with

metal is that the open weave clogs up less. The abrasive lasts longer, quite a bit longer than

regular sandpaper type abrasives. And it just does a great job. So there's probably different

companies that make this kind of thing This is made by Diablo This grid is actually a little fine 180 is a bit fine for what I doing here 80 grit would be better

But anyway, let's take a look and I'll show you how it works

and what clean steel really looks like. Now, that is bare metal

And you can see where the sand are kind of worked through the mill scale

This isn't as big of a job as you might think because you really only need to do it where

you're going to actually do the welding. Later on, subsequent steps might involve cleaning the whole thing that you've made and applying

some kind of paint. But as far as cleaning metal for welding goes, that's the ticket

That's perfectly clean. and you'll get really good results if you turn a well to that