Good carving knives are surprisingly simple items. They only require sharp, well tempered blades with uncomplicated handles. Undoubtedly the world’s most popular folk craft knives (slöjd knives) are mass produced in Sweden and are surprisingly inexpensive. While I cannot replicate the laminated steel blade of one of these knives, I can however do my best using a reclaimed saw blade.
Thanks to the kindness of a very unselfish neighbor, I came into possession of a half dozen used saw blades, suitable for conversion into knife blades. Saw blade steel makes a good choice because it is tough, easily annealed, hardened, and tempered.
I started by annealing the blades, heating them on a propane burner and a 1/4″ plate of mild steel. I then used a Mapp™ gas torch to get them to a bright red temperature. Once up to temperature, I folded the blades and the plate into a ceramic insulation blanket. The plate helps to ensure that the blades will cool slowly thus insuring that they will be as soft as possible the next morning.
The next step is (for a wood worker) probably the least pleasant task. The teeth are ground off the blades, they are cut to length and shaped by laborious grinding, filing and sanding. Personally, I find metal to be dirty, smelly and nasty stuff, but at the same time possessing intriguing properties. I’ll spare you any photos of my mess and suffering and instead share this one of the finished shape.
Once the blade is the correct shape, the next step is heat treating to hardness. The blade is again heated with a combination of propane and Mapp™ gas to the cherry red temperature, then plunged into warm oil to quench. The blade is then brittle and hard as it can be. The oil should be warm to about body temperature, so I used coconut oil which melts at about 75ºF; close enough for our purposes. This makes it easy to tell when the oil is warm enough without a thermometer, and makes it easier to store (when solid).
After the hardening, the blades were brittle as glass and somewhat harder. I again polished the blades to prepare them for tempering.
Tempering modifies the hardness to the extent that the steel is no longer brittle, but will still hold an edge. To temper, I employed our household oven set to 460ºF. I heated the blades for roughly ten minutes until they were a medium straw color, then quenched them in room temperature water. I also tempered the tang of the blades to a softer (blue) point to ensure that they wouldn’t snap off at the handle when pressed.
Next up, fashioning the handle, assembly and final sharpening.
One thought on “Wherein, I make a slöjd knife”
I am amazed at both the complexity of the process and the precision required to make a successful carving knife. And you’ve only described the first half of the project! Kudos to you for both the knowing and the doing.