Making a paring knife from scratch

Before the midwinter I took part in a knifemaking class taught by Ilari Mehtonen. Besides getting valuable knowledge on sharpening, I also thoroughly enjoyed the chance to make a custom paring knife of my own. The Swiss and English knives I use are enormous and somewhat clumsy for detailed work, so this small knife was a much desired addition to my tool collection.

My paring knife started its life as a rough, crooked lump of rust-covered steel cut with an angle grinder from an old frame saw blade (that of a sawmill's frame saw, not the hand-hold tool). I now regret that I didn't take any pictures of this effort, because I broke two disks before managing to get even a remotely decent looking piece from the blade. I had a bad day.



But in the end it worked out brilliantly. Here you can see that I have already rounded one end and edged the piece with belt grinder, so it looks rather nice and has tentatively adopted the form of a little paring knife. After the smoothing and shaping process the blade end is heated to 900 Celsius degrees and given a few hammer blows on the anvil to compress it before grinding it further.




In the following pictures you may notice how I haven't made up my mind on whether to make a crescent or a straight blade. Ignore that. I'm an absolute beginner! It still looks somewhat neat though. In this stage the blade should be already ground close to its final shape, but changes can still be made before the hardening process.



I also decided to decorate the handle with melt brass. The brass is cut in flakes and placed on the knife which, naturally, is propped in the bench vise. Then the whole set is heated with a torch until the melt brass forms a nice sort of moon landscape or whatever it is that you want. This of course has to be done without melting the steel itself too much. If the brass doesn't stick some borax powder works nicely as a flux.



Because I'm a sentimental synaesthetic fool I was very excited about how my creation looked in various stages of the process. Aaaaah the colours, oohhh the texture. After the knife was cooled down I cleaned and polished the decoration slightly with a wire polishing brush.



The blade of the paring knife is hardened and quenched in automatic transmission oil, or a vegetable oil. After hardening the steel is very hard but brittle, so it must be tempered ie. heated back to a lower temperature (in this case approx. 250°C) and then left to cool. This balances the blade and makes it more pliable. Paring knives naturally benefit from the hardness but if the blade is too hard it might become arduous to sharpen. The Thing is to find the right combination for the tool you are making. This is my knife before the final shaping and hardening:



The final sharpening and polishing is done with the help of a bench grinder and several sandpapers of different grits (120, 220, 400, 600 and so on). I do most of my sharpening with a Japanese sharpening stone and strop but good old sandpapers seem to work as well. After all this fun here is the final result, a pocket-sized paring knife with a proper angle in the blade: