Pocket knives, and knives in general, fascinate a lot of people for many different reasons; perhaps you foster some sort of rufty tufty backwoodsman fetish with a need to whittle a toothbrush from a redwood, or you are an artist looking for something to sharpen his pencil, or a motorcyclist who wants a all-purpose multi-tool to carry in his pocket, there is a pocket knife to meet all your whims.
I’ve carried a small folding knife (called a slip joint knife) for years; it originally had a hooked blade which was a nuisance to sharpen and I’ve since ground the blade straight such that I can sharpen it on a flat diamond stone. I was aware that the blade was marked ‘stainless steel’ which experience suggests doesn’t align with keeping a sharp edge for very long!
Tootling around YouTube like you do, I found lots of videos to learn from. I discovered all the terminology used in this post, and I learned that here in the UK your ‘Every Day Carry’ pocket knife can have a maximum blade length of 3” and it mustn’t be able to lock the blade in it’s extended position.
Knives like that, with a spring to return the blade and to keep it folded are called ‘slip joint’ knives; there are lots of styles of pocket knives with locking blades as well.
I bought a strip of 1095 tool steel on eBay - 50 mm x 200 mm, enough to make a few pocket knives. This is the most popular 10-series standard carbon steel (about 1% carbon) with low corrosion resistance and average edge retention properties. It’s a tough steel that’s resistant to chipping, it’s easy to sharpen, takes a crazy sharp edge and is inexpensive to produce but it will corrode if you get it wet - a simple oil treatment will do the trick.
The first thing I did was to make a cardboard pattern of the blade, the back spring and the liners to model the shape of the knife and make sure the spring would work. Satisfied with that, I used the template to mark out the blade on my 1095 strip. Having shaped the blade, I used a compass to follow the edge of the blade and mark where the bevel meets the flat part of the blade - the point called the ‘shoulder’. I used a power file to put the bevel in.
The next picture shows the back spring and the blade cut out - the back spring is not yet complete. You’ll notice the holes for the pins are punched but not drilled, and the spring has not been shaped internally. The blade however is more or less complete - it’s partially polished, the tang has been shaped and the choil or kick, that little notch at the end of the bevel, has been filed in.
The other two parts shown are the liners, which have been roughed out.
Here it gets a bit more exciting - I’ve drilled the spring and liners for the pins (not including the blade joint pin) and set the spring and blade on a piece of chipboard. Next, I've located the blade tang and pin approximately and adjusted the position to give me some deflection in the spring, and drilled the pin hole in the liner. Neither the spring nor the blade have been hardened at this point, and there is some material to come off both if the spring is too stiff - the pin location is set to ensure the spring is not too weak, because we can't correct for that later; which brings us to the lesson. In the event, the finished spring is a bit weak - perhaps through over-tempering, perhaps it’s the wrong shape. The lesson is to leave it deliberately too big until after heat treatment, since you can always grind a bit off.
You can see that I had ground the nail nick by now, using a Dremel cutting wheel in the pillar drill and the blade held vertically in the vice. It produced a thin slot which I enlarged with another grinding wheel; this is easy to mess up.
Drilling the second liner through the first, you can assemble the working parts of the knife and test both the spring and the enclosure of the blade by the liners.
Here's a similar view, but with the back spring shaping finished. At this stage I had liners made from brass, which looks great but they were too thin; I replaced them with 1.2 mm thick stainless steel.
The blade and spring were hardened in my home-made keg furnace, heating to red-hot and quenching in oil. Both parts were then tempered to 200°C in the kitchen oven.
Now, normally you make the bolsters next - that's the stainless steel 'block' you see at the blade joint. You make them next and rivet them to the liners such that when you make the scales - the wooden grips - you can butt them up tightly to the bolsters. I'm writing this a year or so after making this knife and I don't have any pictures of the bolsters during manufacture, but from the next picture it's clear that if I had made them, I obviously hadn't fitted them...
So, the next pictures shows the two oak scales (I replaced these with ebony later) cut to thickness and shaped around the earlier brass liners:
Here's another view showing the knife closed and the point of the blade safely hidden inside:
This next picture shows the final ebony scales and the stainless bolsters. They are made from 25 x 5mm 304 stainless flat bar, and in this shot are fixed in place with rivets made from 2.5 mm diameter 304 round bar. The rivets, being the same material as the bolsters, are invisible after polishing - there are actually three rivets holding the bolster in place.
You'll see the scales are riveted in place as well, in two positions for the moment - they will be further retained when the knife is assembled, making six rivet positions in all. Possibly overkill!
Assembling the knife, with the blade pin going in and temporary pins still in place around the butt end of the spring:
The other side:
Finished:
It's a nice chunky knife that I have on me all the time. The blade blunts easily but as expected is easily sharpened; it will rust but rarely gets the chance!
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