Making a Commision - Part 14 - Sharpening


Unfortunately, I did not manage to sharpen the knives this week, other duties got in the way. However, I have decided to describe the process even so.

Because I am using masking tape to protect the blades against scratches during work, the first step before sharpening is to clean them thoroughly. In theory, I could leave the tape on until after sharpening, and it would be beneficial because it would continue to protect the blades against accidental scratches, but overall it is not practical. The masking tape ages and the longer it is on the blade, the more difficult it is to remove it. Thus I prefer to remove it before sharpening, as it is significantly safer to do.

As far as sharpening goes, no sophisticated equipment is necessary. With a bit of effort, it is possible to get very good results with a cheap two-layer whetstone and newspaper. And definitely better result than with many commercial do das which more destroy than sharpen. However, even though I can sharpen knives with whetstones, it takes a long time, therefore I am doing it with the same belt grinder that I have used for most of my work so far. I reduce the belt speed to 20% and I cool the belts directly with water. And as with many other processes, I am using older and blunted belts, because new ones would get blunt in a matter of seconds due to tiny contact surfaces.

I sharpen kitchen knives at a ca. 15° angle (measured against the middle plane of the blade) and outdoor knives at a ca. 20° angle. An exact angle is not extremely important. The smaller the angle, the smaller force is needed to cut but the dependency is not linear, and only above 25° it is really noticeable.

Cutting-edge durability is, on the other hand, better for bigger angles. Thus more important than an exact angle is a consistent one across the whole blade length. Otherwise, some portions of the blade would get blunt faster than others and that certainly is not desirable. I do have enough experience to sharpen blades freehand, but again – work smart, not hard. So I have made an attachment for the belt grinder.

It is an approximately 50 cm long arm with a ball joint at the lower end and a magnetic holder on the upper end. The ball joints' distance from the grinding plane defines the angle. The magnetic holder consists of three neodymium magnets that hold the knife strong enough so it cannot fall or easily slip, but not so strong that it cannot be simply removed by hand. And a stainless non-magnetic screw provides support for the back of the blade so it does not slip or detach accidentally during work.

I begin the sharpening usually with a 180-grit belt running against the cutting edge, which establishes the bevels in a matter of seconds, depending on the blade thickness. After that, I go for 320 grit and run once-twice over the bevels with that. After this, the blade is already sharp enough for most works. I continue with trizact belts from A45 all the way to A6, although cutting power does not increase linearly with decreasing grain size. After 320 grit the blade cuts paper, after trizact A35 it shaves. However handmade knives do deserve that extra bit of sharpness. Belts A16 and A6 are equivalents of honing the blade with an abrasive-infused leather belt, thus I run them in the opposite direction than all the previous belts.

And that is more or less all. Knives sharpened this way are as sharp as razors and with proper use, they remain sharp for months or even years, depending on how frequently they are used and what materials are being cut. In my experience, they definitively keep edge for longer than cheap knives from the supermarket. However, every knife will need sharpening sooner or later. Who says their knives never need sharpening, is blatantly lying.

After sharpening all that remains is to photograph the knives, calculate the prices, and offer them for sale in the web shop I have not decided yet what to write about next week. Maybe about photographing.