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Easy DIY #62 Forge A Knife From A Piece Of Steel

Forge a knife yourself! In this week’s article I’ll tell you how I made a knife from a piece of scrap steel at home, using a home-made forge!

Not everyone likes the idea of making things this way, and I can’t say I blame them! After all, forging is hard, hot, tiring and dirty work! There’s also an element of risk – that is, risk of serious injury! So yes, this is not for everyone – in fact, it’s probably best to watch a few dozen videos on YouTube about forging your own knives etc. before embarking on something like this – just to see if it is really for you, or if you’d rather buy a knife than make one in your own style!

Preparations:

Before you can forge anything, you need a few basic tools – a plier to hold hot metal with, preferably something with big enough jaws to grip the rough unshaped metal as well as the more refined shape of the blade as it gets worked. Safety shoes are a must – you don’t want a lump of red-hot steel falling out of your grip and landing on your toesies, do you? As someone who arc-welds on occasion, I can tell you about all the times a blob of hot metal have fallen and burned through the pair of old takkies I use in the workshop – and the socks – and past or into my skin! Not pleasant!

For the same reason, you should look for a pair of safety gloves, nice robust leather gloves that will protect your hands from coming into contact with scorching hot metal! A pair of clear safety glasses will keep your eyes protected.

A hammer is a must – and if you plan on working on small items, say a small knife blade, or other little items such as pendants, bracelets, homemade locks or cupboard handles etc., you could go for a medium to small size hammer, or even better, have a selection of differently sized and shaped hammers handy.

Next you need an anvil. These are very very pricey items indeed, so I wouldn’t recommend rushing out to buy one from the local horsey-people’s shop – at least until you’ve decided you like doing this enough to want to invest in moving up to the next level. A smooth concrete step or block will do just as well at first – or if you find a bit of steel train rail, even better. As I detailed some time ago in an earlier article, I built myself an anvil from railway rail. (link)

Then we come to the forge itself, which is basically a heat source, or an oven to soften steel. There are a lot of different types of these things, and there are almost none available commercially. There are loads of videos on YouTube that cover how to build your own forges, the different types you could choose to build, to just making do with a shallow pit in your garden, a few bricks and wood or coal. Whatever – the choice is yours, and it really depends on your personal circumstances. Some people opt to buy a forge custom made for them by people who make them as a sideline privately, in the same way as some people build steel braais in their garages – you can find a guy advertising gas forges on Facebook marketplace.

I opted to start off with a small gas forge which I built according to a video I saw on YouTube, using a 5 liter metal paint tin, which I then lined with plaster of paris, leaving a hollow channel down the center. I got the plaster of paris at Builders for not much. A butane gas torch is inserted into the channel through the side to provide heat, and all in all, for a very small gas forge – for small projects, this has served my purposes thus far.

A quenching tank to be filled with a quenching liquid. You could use a bucket, preferably metal, but plastic would do if you don’t touch the sides with hot metal as you dip it. Don’t use plastic with oil, because if it lights on fire, the plastic bucket will melt, sending a flood of blazing hot oil everywhere!

Different people swear by different things – water, oil, sand. There are special quenching oils you can buy – at a premium. I really wouldn’t recommend using oil at the start – it’s flammable and there’s a huge risk of disaster if you don’t know what you’re doing. Water has its own risks, and can cool the steel too rapidly, causing cracking and even breakage. Still, with a small forge making small things, you’re not likely to heat the steel that much, just enough to make it malleable to move it, so water is fairly safe to start off with. Sand is good to quench too – but is slower than water or oil. That said, it is probably safest, since it won’t crack your blade, or light on fire!

Lastly, always have a fire-extinguisher handy, even if it’s a few buckets of sand. A small water extinguisher is very affordable and good to keep handy for these occasions. Remember this is fire we’re working with, and fire has inherent risks, and as the man said, “shit happens” – and it usually happens when we least expect it. Use common sense – avoid placing flammable materials near your forge, and always THINK before you DO.

Thus armed and prepared, a few December holidays ago, I was ready to embark on my first knife-making exercise!

The Knife:

I started out with the U-shackle of an old broken lock, which I placed inside the forge to see if it would fit, and for placement. Then I lit the gas torch and inserted it into place so that the flame filled the channel, washing over the steel bolt.

Once the bolt started to glow red and then closer to white, I gripped it with a plier and placed it on the anvil to hammer it straight. You have to work quickly with hot steel, because it cools quickly – which you can see as the red fades away. Don’t be fooled though – it’s still as hot as hell, but hammering it like that can cause the metal to crack and fail. Rather put it back into the forge again for a few minutes until it heats up again.

After a few of these cycles, I got the bolt to form a nice flat, even semi-blade shaped thing, which was about right to start working. I shut off the forge, turned off the gas, and cooled the blade.

This done, I took out my belt sander and mounted it upside down on my workbench. I put on my rubber work gloves to keep my fingers safe, and then applied the blade against the belt on both flat surfaces to smooth them out so it looked more like a blade and less than a glob of congealed lava! Then I shaped the blade by working on the edges.

Afterwards came the finishing – drilling holes in the tang to fit the handle, and cutting of the handle itself. I used some nice strong wood I had lying around. Before the fitting of the handle, before sharpening the blade, it was time to do the final quench, which will harden the blade.

This meant firing up the forge again, heating the blade back to red-hot again, and then giving it a last taste of sand, water or oil. In my case, I used a 1kg metal coffee can containing clean cooking oil. After the blade had cooled, I applied the file test, by which you judge if the blade has hardened – in which case the steel file will skate across the edges without “biting” into the metal. If it isn’t hard, you’ll have to heat it and quench it again. Once hard, it’s time for finishing.

Finishing:

Finishing entails the sharpening of the blade, polishing, and fitting the handle. I fitted the handle to the knife by slotting metal pins – essentially long nails – through the wood plate on one side, passing through the holes and through the wood plate on the other side. The I cut the nails off on both sides a little longer than necessary, so that they protruded past the wood. A few precise taps with a hammer on the anvil flattened their ends out to keep the handle sides firmly attached to the knife.

A little polishing and it’s done!

The knife in the photos was one I made for cutting biltong.

That’s all for this time – have a DIY day!

Pictures included!

Enjoy!

Cheers!


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All material copyright © Christina Engela, 2021.

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