Zedteq Hunting Knives

Darren Englebretsen, New Zealand

For those who are interested in the machines I use some photos are on my equipment page.

Steel

I use recycled L6 high carbon circular sawblade steel for my knives. The advantages of this steel are that its heat treatment procedures are well known and relatively simple, and it can be tempered to yield a knife with a good balance of hardness and toughness. In addition blades can be edge quenched, giving a knife with a hard, tempered edge having good edge retention backed up by a tougher, more flexible back. The downside of such plain carbon steel blades is that they will rust. This can be partly prevented by not storing the knife in its sheath when not in use, and cleaning and drying the knife carefully after use then wiping with a fine machine oil. Any rust spots that do form can be removed using 3M Scotch Brite™ or similar non-metallic scouring pads.

Blade grinding.

I hollow grind my blades on a home-built linisher using a 250mm contact wheel. Belt size is 2745mm x 50mm, and belt speed is approximately 1000 surface metres per minute (about 3900 sfpm). The blades are ground by hand and the sides are mirror imaged by eye.

Heat treatment

I do my own heat treating using an electric temperature controlled furnace, with the blades being double tempered as described below:
- austenize 840 - 850 °C, 10-15 minutes
- edge quench in engine oil
- temper immediately for one hour at 200 °C, cool to room temperature
- cool to minus 18 °C for two hours, warm to room temperature
- re-temper one hour at 220-240 °C
This procedure imparts a nominal Rockwell hardness of C58-60*. I double temper my blades as this can increase the final toughness of the steel without sacrificing hardness. All further grinding of the tempered blades is done wet and with great care to preserve the temper of the steel. The tempered blade is surface ground using a belt sander surface grinder to remove the hard black oxide scale which forms during heat treatment, followed by finish hollow grinding of the bevels.

* (ASM Metals Handbook, 8th Edition, 1964, Volume 2, p241)

Inletted half tang construction method

Inletted half tang

The knife blade is made with a half tang the full length of the handle. The wood for the handle is inletted along the top to a depth of approximately 15 mm. The tang is inserted into the inlet and fixed using two pins as well as with epoxy glue. A photo of a half tang compact skinning knife is shown below.

Final finishing and sharpening

Once the epoxy has cured the handle is machined and sanded to final dimensions. Wood handles are finished with boiled linseed oil or Danish oil. The blade is finish sanded then sharpened using a Norton IB8 oilstone followed by an extra-fine natural stone to give a shaving-sharp edge. The blade is finally coated with a thin layer of wax to retard corrosion.

Testing

I have done more than 30 breakage and other destructive tests on examples of my knives to satisfy myself as to the suitability of the design, construction method, manufacturing and heat treating steps. In addition each knife is subject to continual inspection as I perform the various steps in their manufacture.