Forging a iron age knife
first wood working tool made
Will jump right in to my first blacksmith tool making project in the work shop, I decided it should be the most basic tool for a Woodworker, Lumberjack or Lumberjock – a knife. As a Dane I felt it made sense to start here, this type of knife are often mentioned as Viking knifes, but they are dated back to the iron age.
(The truth is that even I thought it was a Viking knife type).
The type has ben found here in Danmark, in a place called Dejbjerg and are dated to 100 ad.
I start in our time…
The knife will be made from a piece of car spring steel that I found in the street on my way home from the workshop one day.
Car springs have a relatively high content of carbon and are clean, this makes it ideal for forging tools.
You need a high carbon content of the steel to be able to harden it like this.
Steel can also be bought from a commercial seller and are actually relatively cheap.
Here the iron are getting up to forging temperature in my wonderful new gas forge.
The forge are amazingly fast to get the steel there and like this forging is a dream.
Also you don’t get the steel too hot so easy, since you can control the temperature by the flow of gas.
If the iron gets to hot it will melt or for the carbon steel it will ‘burn’ sparkle off.
If not hot enough you will not be able to form it and the steel will get stressed.
You don’t need a fancy gas oven, you can use coal or make a soup can forge really cheap, the web is full of these getting started videos. I am thinking of making a soup can version just for the fun of it, if you can get hold of ceramic felt, this oven can be made in half a hour, otherwise you can make a more at hand version with Perlite.
Look at the video here: https://www.youtube.com/watch?v=uIRTcmR6sSk
The key is in the color, here you can see them.
Found this online.
A simple hammer is all I have for now for the heavy part, so this will have to do.
But the workshop are set up for forging now.
I decided to protect the wood floor with aluminium plates before I went on and on the floor you see a bucket with oil for the quenching process. Yes we should be ready to go now.
Once the steel is hot, it’s time to hit it with the hammer.
The anvil works great and the tools are at hand when needed.
In and out the forge.
Hammering it to shape.
I’m really enjoying this process, everything are working fine in the flow.
Perhaps I need to place the forge a little higher so I don’t have to bend for looking inside.
The color you see on the tip is a good color for working the steel, here it’s soft and will be formed without cracking.
But you relatively fast get a feel to when it makes sense to form it.
Here you see a piece of spring and what it becomes.
I’m quite pleased with the way it works out, for a beginner I feel happy.
Soon this is where I get to.
I smile and look at the new work area.
Even possible to take a rest here on goat skin, what more can a man ask for…
I leave the blade on top of the forge to cool down slowly.
Like this it will become soft and I can work in it.
Once it is cold. I start to shape the blade profile and even out the taper with a file.
I have done as much of the shaping I could manage on the anvil.
But I found the steel a little hard, so I re heated it to red hot and then left it in the forge to cool down, this time waiting a good hour before I took it out.
(I must have been to quick before, then the steel hardens up, so patience is the key word here).
Then it was much easier to work with.
I finished it up with sand paper, not too carful since I wanted this to be fitting the raw steel.
Don’t finish the edge here, leave it stump, like this it will not get wrapped when heat threating it.
Some will at this time do one or two runs where they heat it to red hot and then leave it to slow cool, like this the blade will be at rest, the tensions will be out of the steel, I will go directly to the tempering, I believe in a small knife like this, it will not be an issue, but time will tell.
Then back in the forge, warm it up again.
This time back edge up and the whole blade gets heated, but the handle stays cooler to keep this soft.
Then with a magnet test if the steel is hot enough, once it is no longer magnetic, it is more than 850 degree C and ready to be put in the oil.
I use canola oil it was cheap, easy to get and smells like cooking when used.
At my first go I did not preheat the oil, this resulted in a blade that was not hard enough, so I made the oil hot and then did it again, this time it worked and the blade seems to have a good hardness.
(I scratch it with a file and it leaves no marks).
Then while it’s still hot I give it some bees wax, this should help to rust prevent the blade.
(Advice from fellow LJ Brinth, thanks).
After sharpening the blade looks like this in the daylight.
I make a quick wooden sheath for it.
Just a sandwich construction glued together.
Thas the shortest wood working description ever here, lol.
Then home to make dinner for my daughter and girlfriend.
And to use the heat from the oven to temper the blade.
I give the bred five minutes and the blade one hour at 200 degrees C.
Before you temper a blade it is tense so it can snap if you hit it with something hard, the tempering makes it relaxed and flexible, so it is a process you don’t want to skip.
For dinner we had marinated halibut.
And a burger.
Ok back to the tool making.
Here the blade is out of the oven and left to cool down on the pan.
You can see how the blade got the straw yellow color on the edge, this means that it is tempered rigt.
Also I gave it a wax again for the rust protection at this stage.
This is it after the final sharpening.
I am happy and a wee proud, now I have really gone full circle in the little shop.
Life is sweet and I feel lucky.
And finally in it’s sheath.
Now this is a wood working project. ;-)
Hope this post can inspire others to make their own tools, after all this is why I take a detour out the black road now.
-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.