Build your own mechanical drum machine with interchangeable parts :)

How to play:

Swap gears or add/remove a peg to change the tempo, reposition the piezo triggers to change the sound/rhythm

I used an external sound module (Roland TD3) in this project. Check out this post by Ryo Kosaka if you'd like to make your own Arduino MIDI https://www.instructables.com/Arduino-Minimal-Dru...

Supplies

12V DC Motor

MDF/Plywood 3mm

Piezo

Jack connectors

(optional) Ball Bearing (Inner Dia.=8mm, Outer Dia.=16mm, Thickness=5mm)

Wooden Dowel 8mm

Braided Sleeving

Step 1: Making Gears

I lasercut 2x 3mm plywood and glued them together (the reason is simply that my laser cutter isn't powerful enough to cut 6mm) 6mm is a suitable thickness as you don't want it to be too thin. if you don't have a powerful laser another option is 3D print:

you can also use https://geargenerator.com/ to design gears, make sure you use the same pressure angle and diametral pitch for all gears.

I have used ball bearings to connect the dowel and the gear but if you make the hole on the pegboard slightly larger than the 8mm dowel, and glue the dowels to the gears, it should work smoothly without ball bearings.

Step 2: Making Pegboard

I designed the pegboard in adobe illustrator. It has small holes to hold the 12V DC motor (you'll need to adjust it for different motors) I recycled this motor so I don't have a link.

I actually reduced the voltage to reduce the speed/torque just in case my finger gets caught between the gears the motor will stop.

board1.ai
Download

Step 3: Mounting Gears Onto Motor Shaft

I used lasercut but the 'right' way is using a shaft mounting hub. See

Step 4: Making Piezo Stand and Solder Jack Socket

I used aluminium soft wire to support piezo and PET expandable sleeving to hold wires together. I used 4mm sleeving - it depends on the size of the piezo copper wire and aluminum wire (yours might be different)