Making Santoku - Part 1

The break was longer than I would like it to be, and the cutting boards are currently in limbo, but I got a commission for a santoku knife, so I am returning to the workshop for a bit.

A santoku is a universal kitchen knife of Japanese origin. I am not Japanese, and I do not feel bound by Japanese tradition; therefore, my santoku will differ from the original Japanese design in some aspects.

The first difference is material – I will be using N690 steel, a corrosion-resistant steel from Austrian company Böhler, developed specifically for knives. Stock thickness is 1,8 mm, which is, in my experience, ideal for small and medium-sized kitchen knives.

Work begins by drawing a template in Photoshop. After the customer approves it, I print it out and transfer it to the steel. The little targets near the tang are for a center punch to mark points for drilling holes. The transition between the tang and the blade must not be at a sharp angle, and drilling holes there guarantees a curved transition and makes it easier to cut out the rough shape from the stock.

Drilling the holes takes just a few minutes. A slight deviation from standard steel drilling procedure is that I am using a lot of water with a tiny amount of detergent to cool and lubricate the drill bit instead of cutting oil. N690 requires aggressive cooling, especially when drilling small holes with high friction. When using oil, it did happen that it burned off in the middle of the hole; then the steel hardened, and that was the end of the drill bit and drilling in that particular spot.

After the holes are drilled, the next step is to cut out the rough shapes with an angle grinder.

Rough shapes are, of course, full of burrs, and they are slightly bigger than the intended product.

I use an old, worn-out belt to shape the blade contours. The commission is for just one knife, but I am making more blades – some are for continuing another project, but two are for this commission. Why two? Because when hardening the blades, they can crack. It does not happen often; I estimate it to be one blade out of twenty, but when making a custom blade, I prefer making two to improve the odds. If both come out OK, the second can either go to storage for future use, or I can finish it and offer it for sale in the web shop.

After I shape the blades' outlines, I fix a file guide on each and shape the shoulders with a round file for sharpening chainsaw blades. The file guide keeps the shoulders aligned and straight, and the round file maintains the curved transition established by drilling the holes at the start.

Next time, I will continue by shaping and hardening the blades.