How to build a bush crafts knife

Last month I attend a bush crafts event that take place near Grampound Road in Cornwall.

I volunteer to do some demonstration on how to forge and build a knife in the field, using basic / primitive tools. I thought to myself : maybe I can sale some of my knives. So I made eleven knives. The knives design base on my One and half Days Knife Making Course.

Bush craft knife

In this post and probably in the next few I will talk trough the process of making those knives, and how I made the sheath for the knives.

Therefore the proper name for that post need to be:

How to build a bush crafts knife, and how to make the sheath for it.

As my writing ability is not so good(say the least) I will write the post as if it is a food recipe. It will be more coherent.

Ingredients:

For the knives.

Car suspension spring leaf, roughly measure 14×65 (length unknown) mm.

10mm diameter brass rod.

4mm threaded rod.

8-9 oz. leather hide which is around 3.2mm. I used two deferent colour hide.

Propriety plastic spacers, 1mm and 2mm thick with various colours.

Hard wood, poplar and lemon wood.

Linseed oil.

Salt.

55% Silver 1mm silver brazing rods.

Nail varnish.

Acetone.

2 Ton long curing time two component clear epoxy.

For the sheath:

5-6 oz. natural tanned leather hide which is around 2.4 mm.

Contact cement adhesive.

18/6 Waxed linen sewing thread.

Nickel plated open D ring.

Nickel plated 9mm cap size two piece tubular – single cap.

Alcohol base leather dye.

Brown and colourless shoe polish.

Preparation:

To begin with I draw the knife, dimension it and make sure that I have all the tools that I need to shape the blade and the handle. all the sanding drums need to fit to the curves of the handle and same goes to the router bit to roughly shape the guard part of the handle. Bush crafts knife

I started by cutting the steel . I use car suspension spring leaf.  It is I believe a spring steel (5160?). Bush crafts knife

I have a lot of experience working with that type of steel. I can bring it to around 55-58 RC. The blade is hard enough to hold its edge, the blade can’t be broken, it will bend but not brake. It is not as hard as all the new exotic steel but, it is lot cheaper to get and it is a lot easy to sharpen. Especially in the field, one can sharpen it using any old granite stone, red clay brick, roof till or any object made of concrete.

I cut the steel to 120x 23mm pieces, using angle grinder. To each peace I weld a 600mm long piece of re-bar to serve as  handle. One can use tongs, but I found that it is more comfortable using the rebar handle.

I forged the blades in my gas NC forge. I work against a knife template to ensure blades shape consistency.  Bush crafts knife

Next I shaped the blades profile, again, sing the template as a guide.

Bush crafts knife

Now it’s the turn of the belt sander. Establishing the knives bevels, progressing from 60 grit belt to 80 to 120 grit. I left part of the blades unpolished, mainly the blade spine and the ricasso.

Bush crafts knivesBush crafts knife

 

 

 

 

During the process of  forging the blades, I didn’t pay a lot of attention to the tang section of the blades. As consequence, some of the tangs happen to be offset from the template profile. that will affect the shape of the handle. So I built a jig to help me marking the exact centre line of the tangs, exactly as it supposed to be.Bush crafts knife

In preparation for brazing the threaded rod, I cut slots at the end of the tangs.

Bush crafts knife

As you can see the position of the slots are not the same on all the blades. That is to compensate for the sloppy tangs forging.

Now it’s time to give the blades the heat treatment. That will transform the metal from relative soft metal to hard, one that can hold its cutting edge sharp for a long time (time is relative).

I bring it up to critical temp’ and try to keep it at that temp; for few minutes. Then I quench it in pre heated transmission oil. Let it cool completely and check for the RC harden rate. If all is well I then tempered it in my kitchen oven at around 176 C for one and a half hours for three times . If after the quenching it’s not hard to my satisfaction I re quench it and check again, then tempered it.

I finish polishing the blades on my belt sander (this time without the jig), using belts from 120, 240, 400, 600 grits, make sure not to grind / polish the unpolished blades spine and ricasso.

I silver brazing the threaded rod to the tangs. I lay it on heat proof brick and weld. I can’t say I am fully satisfy with the end result but, it was strong. Next time I will use thicker silver rods (2mm) and keep the tang and the threaded rod away from the brick. Maybe in vertical position and not horizontal against the brick. Bush crafts knife

when you solder the threaded rod to the tang, you must make sure that you are not hover heat the blade.  you can deep the blade in water leave the tang portion that you weld outside.

That it.

Next post I will talk about the threaded brass bolt, that lock all the handle materials together, on to the knife blade. I will continue to construct the rest of the knives i.e. the handle and how I finish / polish the knives.

 

 

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