Press Eye View

I stuck a GoPro on the end of the die of a Coal Iron forging press.

This is not my billet, but it’s a fair illustration of what setting a stacked weld looks like. You get the steel around 2300F and flux it up nicely, wait till the flux starts boiling, and smush it gently. By the time the first smush is done, the metal is a single piece.

When you are dealing with forged welds, you need to get out of your mind the idea that there are two pieces of metal (or whatever) anymore. After the weld takes, it’s a single piece and it’s not going to come apart. If it comes apart, it was not welded, Q.E.D.

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The die is only about 6″ long, so the camera was about 5″ from the metal. That’s a nice thing about GoPros: they are not quite disposable but with the wifi/app control you can put them in places where you really don’t want to have your hand.


  1. sonofrojblake says

    GoPros may not be disposable, but you can get acceptable substitutes for a tenth of the price. Not broadcast quality, granted, but you really can put them anywhere and not worry about cost.

  2. says

    What’s the stuff spalling off the metal?

    It’s usually called “forge scale” or “hammer scale” – it’s oxidized steel. Usually that’s a mix of Fe3O4 (magnetite) and other trace minerals that are in the metal.

    It’s weird stuff. It’s tough as all get-out and it forms faster depending on the temperature and what you’re doing to the steel. Blacksmiths are constantly sweeping it off the anvil or their tools, because if it is allowed to remain, it can get hammered back into the steel and it’ll stick. Then you get a big chunk of this incredibly tough slag-like stuff that an angle grinder or a file just skates across – it’s like glass. I believe that it’s sometimes collected and hammered to powder and used as abrasive (“carbide”)

    A lot of smiths use a technique of thermal shock to get it to blast off the work-piece on an anvil: you puddle water on the anvil and the hammer. When you hit the bar, the steam gets in/under the scale and blows it right off the piece (usually onto the pants of the guy standing next to you, who then has a hole in their pants)

  3. Badland says

    Thanks, Marcus! I deal a lot with magnetite in my job (geologist) and had no idea it could form during forging.

    It’s been fascinating to follow your descent into forgery btw and I’m genuinely sad I missed out on one of your knives. They were beautiful

  4. Dunc says

    Archaeologists love hammer scale, because it’s never completely cleaned up (at least in antiquity) and lasts forever. Even if all other traces of metalworking have been removed or lost, that stuff sticks around unless you lose the entire layer of soil. It also doesn’t usually travel very far, so you can use it to locate the former sites of anvils very accurately.

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