In this video, I show how to make a knife for Kabab Barg which is a Persian style barbecued
lamb.
The blade is going to be about 12in long and 2in wide.
The knife needs to be very sharp for cutting fine slices of meat.
I will forge the blade from antique wrought iron for the back and a high carbon steel
for the cutting edge.
In the first step, both the wrought iron and the high carbon steel are prepared so that
they can be forge welded together.
I am aiming for bars that are about 3/8in thick and a little bit less than an inch wide.
Once the bars have the right dimensions, they need to be cleaned up and fitted so that that
they can be successfully forge welded.
While it clearlier would have been much simpler to start out with stock that was already the
right size, I only had big bars of wrought iron and W1 lying around.
During forge welding, the two bars are joined together in the forge fire until they behave
like a single piece
of metal.
After the pieces have been forge welded together, the tip of the knife is created by reverse
cut that will be forged over.
This creates an aesthetically pleasing flow of the W1.
After the knife tip has thus been created, I establish a distal taper that reduces the
width of the blade as it gets closer to the tip.
One of the tricky parts in creating this knife is forging in the shoulder that clearly separates
the blade from the tang.
To do this I drive a wedge into the steel with the power hammer.
It is important to support the blade evenly on the bottom die so that the back of the
blade is not being distorted.
Afterwards, I draw out the bevels using a helper on the power hammer and also by hand.
As the forging in the bevels causes the knife to bent, it needs to be straightened out occasionally.
Another shoulder needs to be forged in to create the tang.
The power hammer makes this quite simple.
At this point the knife has been completely forged.
I heat it up to critical and let it cool in the air to normalize the metal.
The remaining steps are quite time consuming.
The scale needs to be cleaned off the blade and then the final geometry is established
by spending many hours with the belt grinder as well as by draw filing.
Once the edge has been thinned, the knife is ready for heat treating.
The first step is to normalize the knife again.
Once it has reached its critical temperature, it is slowly cooled down in the air.
By criticial temperature I mean the temperature at which the blade is non-magnetic and all
carbon has been disolved into the iron.
The next step in the heat treating regime is to quench the blade when it is at critical
temperature to rapidly cool it down.
This causes maretensite to form which creates the hard cutting edge.
Using a file to test the edge result in it skidding over the surface rather than biting
into it.
The last step in heat treating is to temper the knife.
This reduces the hardness but makes the steel tougher.
For this knife I temper at 400 Fahrenheit for an hour.
To fit the bolster I use a file guide to create a small transition which helps with achieving
a tight fit.
At the back of the knife is wrought iron, a file cuts it without much trouble.
However, to file the W1, I need to more aggressively temper the steel.
Rather than drilling and filing the slot in the bolster, we use the blacksmithing approach
in which a slot is punched and then opened up to the right dimension with a drift.
This is much easier as a two person operation.
The final fitting is done using the tang of the knife.
I use a stencil to scribe an oval shape onto the bolster which I then use as a guide when
grinding.
For the handle, I use a piece of African walnut on which I trace the outline of the tang using
a pencil.
Holes are drilled using a drill press and a long drill bit in a hand held drill.
These holes guide the tang as it is being burned into the wood.
Burning the tang into the wood requires many repeated cycles of heating up and burning
it in.
It's not quite as simple as it appears on the video here.
At this point all the pieces fit together and the handle needs to be slowly shaped.
Now is also a good time to start making the knife sharp by thinning out the edge.
All vertical grinder marks are removed by sanding the opposite direction by hand.
To bring out the structure of the wrought iron, I place the blade for ten minutes into
ferric chloride.
The final step in assembling the knife is to glue everyting together using a fast setting
epoxy.
Once the epoxy has fully cured, the transition between the bolster and the handle is cleaned
up on the belt sander.
Great care needs to be taken not to cut with the belts into the blade.
Afterwards, the wood is sanded down by hand to 220 grit in order to remove all marks left
by the belt sander.
To seal the wood, I use True oil which is a mixture of linseed and tung oil.
For this knife, I applied 5 coats which are cleaned up with fine steel wool once the oil
has dried.
Before the knife is completely finished, it needs to be sharpened.
I used oil stones for this which progress from coarse, to medium, to fine.
And here is the finished product.
A big knife for cutting thin slices of meat.