How I made a laser cut wood sheath for a round knife

A round knife is used in leatherwork. They are very sharp and need to be stored safely. Most sheath’s look like you would expect a leather project to be. But I wanted to try something different.

I was inspired by the Joker from the movie “Suicide Squad”. The joker in the movie is quite creepy with these metal teeth. I’m not a huge fan of creepy projects but I also loved the style of the joker in the movie and decided to base my design off his shiny teeth. My goal is to use the blade for his teeth and to secure the blade safely with leather straps.

I sketched out a few ideas and felt like I had a good idea of what I wanted to create.

We will have 3 layers for our project. The 2 outside layers will be made out of wood creating the teeth. The inside layer will be made out of leather and will serve as a welt. A welt is a layer in the sheath that protects the sheath from being cut open by the blade. This layer will also create the space for the round blade to fit between the wood. The round knife will be secured with 2 leather straps and studs.

Here’s my round knife. I took a photo of it on a flat service with a ruler to scale it properly in Adobe Illustrator.

Once inside of Illustrator I set the transparency to around 50% to make it easier to draw on.

If you don’t see the transparency window, go to Menu -> Window -> Transparency

Locking the image so I don’t move it around as I work. You could also put it into another layer and lock the layer.

Menu -> Object -> Lock -> Selection

Since the photo of the blade is not 100% accurate I also measured a few critical parts of the round knife. This way I knew I had the correct distance to the parts of the blade. I made these lines a different color and locked them in place.

First I created the outline for the blade. This is the line for the welt the blade will rest on.

Now we add some lines for a basic welt shape. We will refine this later to match the outline of the lips.

I used the reflect tool to mirror the welt.

Use the direct selection tool (keyboard shortcut “v”) click and drag to select all the lines.
Select the reflect tool from the tools panel (keyboard shortcut “o”)
Left click the point you want to mirror
Left click off the object and hold left click
Move your cursor to rotate
While holding left click, hold shift to lock the rotation to even increments
While holding shift and left click also hold option/alt (mac/pc) to duplicate the object
Once the object is mirrored in the correct spot, let go of LEFT CLICK. Your object should be duplicated and you can now let go of everything

Here’s the lips I created.

Now we add some teeth.

The teeth are filled with white but need to be punched out for our laser to cut. We will use the pathfinder tool to do this.

Now I line up the teeth over the blade.

I copied the teeth and the welt to a new layer. We need to trim the welt to match the lips.

To make it easier I switched the fill of the lips to an outline. (Keyboard shortcut “Shift x”)

We will use the shape builder tool to trim and combine the parts of the welt we want to keep. Hold “alt/option” and left click and drag to delete. Hold left click and drag to combine.

Duplicate the teeth and put them in whatever format you need for your laser cutter. I’m using a Glowforge Pro and will be exporting them as an SVG.

I’m using some ¼ inch plywood. My settings are 170 speed at full power. I set the leather welt to “ignore”.

Anyone missing a tooth?

For the leather I’m using veg tan leather. My settings are 200 speed at 80% power. I deleted the wood parts.

Adding a little burn to the lips/teeth.

The studs I got were too thick for the inside. I had to drill out the holes. I could have done this with a deep engrave but did not think of it until I had already printed the parts.

The final product is really cool and I’m happy with how it turned out. Lessons learned as always but I’m satisfied with what I accomplished.

Design on my friends,

Matt-