How To Make A SlipJoint Pocketknife

Now it’s time to make the knife’s liner. Take the black magic marker and color in enough of the 1/32 inch brass sheet to be able to scribe around each of the original knife’s sides. Cut the brass pieces out with a band saw or a hacksaw and grind them close to the shape of the original sides. I usually try to grind the pieces to between 1/8 to 1/16 inch outside of the scribed line as seen in the second photo. This gives me room to fit everything up. Flat sand the brass pieced to remove any burs from grinding.

Compare the two brass sheets, and lay out the blade and spring on the smaller of the two. Mark, drill, and pin the pivot hole for the blade pin and the center hole for the spring pin. Next, remove the blade’s pivot pin, and rotate the small end of the spring down about two millimeters as we did earlier. Mark and drill a hole in the liner through the spring’s back hole. Fit everything up back on the board with the pins in. The spring should be under load, and you should be able to snap the blade open and closed.

Place the liner with the holes in it on top of the solid one. Drill through the top liner and place a pin in each of the holes. Placing a pin in each hole after it is drilled will help keep the liners lined up. The drill bit will leave sharp burs on the bottom sides of each brass piece. Flat sand these burs away before moving on.

Put the knife together and see how it works. It may be hard to put the pivot pin through the blade because of the load on the spring. A trick I use is to sharpen a long taper on the end of the pivot pin. Stick the sharpened end into the hole and work it back in forth until the blade loads into the correct position. The knife’s action will probably be pretty rough at this point, and the blade may disappear into the liner when closed. With the knife together, grind the liners down closer to the final shape of the knife. Remove the blade from the liner and round the ends off so that they match.

Take the knife apart, flat sand the liners to remove the burs, and put the knife back together. Open and close the knife a couple of times and see if you like the way the blade sits in the liners. If you don’t like it, do a little more grinding and sanding on the liners until you like the way it looks. Once you are satisfied, take the knife and clamp two of the pins up in a vice. Use a Dremel tool with a cutoff wheel to cut the nail nick into the blade. If you want the inside of the nail nick to be black, than it needs to be cut before heat treating. This will create scale down in the nail nick, and it will be black when the blade is completed.

In order for the blade to open and close more smoothly, the width of the tang needs to be the same size or slightly thicker than the width of the spring. Measure the end of the spring with a micrometer or a caliper. If you don’t have a measuring device, you can lay the pieces on a flat surface and just eyeball it. I usually try to adjust the blade and spring to either be the same thickness, or I make the blade one or two thousandths thicker than the spring so the spring doesn't bind up, and so there is no play in the blade. If the blade is thinner than the spring, you are going to get some play.

This is the only time that I use a grinder on the sides of the tang or spring. Hold the tang or spring lightly against the disk grinder. Do this for each side of piece you are adjusting. If you don’t want to use the grinder for this step, you can bring the sides down with sandpaper as seen in the second photo.

Place the blade between the liners and check to make sure that it lies evenly in the center. Make the necessary corrections if it doesn’t. Put the pins back into the knife and work a drop of oil between the blade tang and the spring. The knife should now snap open and shut nicely.