Introduction: Sprocket Chopping Knife

About: Hi, my name is John. My hobby is to solve problems from other people and creating nice and functional stuff out of trash. I'm living in Germany so excuse my not so fluent English (some technical terms are hard…

My wife wanted a Chopping Knife since forever while she was nagging about something I've scrolled through instructables... Accidentally I said Yes to something.

The idea was to build one out of a old sprocket from my bike. It Took me something about 3h to build it. I was supplied with two coffee from my wife and used only standard tools like a drill and a angle grinder.

Step 1: Find Some Sprocket

I dive something like 5000-6000Km every year with my bike. These are 3100-3700 freedom units. The chain and sprocket are changed ~once a year.

For this projekt I'm using a SRAM x12 set...

Step 2: Preparing the Sprocket

... especially the 50 teeth (the biggest). Therefore the rivets needed to be removed. Then the sprocket was mechanically cleaned halved.

Step 3: Grind Away the Teeth

For the cutting edge we need to remove the teeth.

Step 4: Sharpen the Blade

To ease the process of having two identical parts I've used some screws to hold everything together. Then I've used my angle grinder to grind on a first edge. With a sharpening stone I've finished the sharpening for now. (I'll try to harden the blade in the future to further increase the sharpness)

Step 5: Crafting the Handle

As a handle I'm using some V4A steel which i found in my garden... don't ask. To mount the handle to the sprocket the same holes like the rivets before were used.

Step 6: Stiffen the Two Blades

To make the two blades as stiff as possible I've cut down some brass tube and added some screws. This way I have more then enough structure added and it feal like a solid pice of metal, zero flexing.

Bikes Challenge

Runner Up in the
Bikes Challenge