mechanical design, machine design


design a machine that includes mechanism+actuation+automation
build the mechanical parts and operate it manually

Cube engraver

The idea is to build a machine that mills a cube from all 6 sides without taking it out and putting it back in.
This should be set up so that you have a 3-axis CNC milling machine which can engrave on a surface of 3 x 3 cm. Then the machine has a display on which you can choose your model. Behind the display there is a Rasbery Pi which controls the CNC and the dice turning The cube itself is turned and held by a mechanism as soon as it receives a message about i2c from pi. The last part is my task in the project.


We still had rods for the axles in the laboratory. It took us a lot of work to shorten them to the right length. Neither with a metal saw nor with a lathe we could do it. In the end our neighbor lab had a flex and we could shorten the rods.
The rest of the parts we have ordered on Amazone:

Individual part:

Cube turner

One task is to fix the cube and turn it automatically. This is best done with 2 motors. I have started to fix the cube.

I thought about designing a 4-jaw chuck which can be controlled by one motor.


To control the turn of the cube I wrote a small program which receives a message via serial communication. Then it lets go of the cube, turns the other motor by 60° and tightens the cube again.

        int SPU = 2048; 
        Stepper dreh(SPU, 2,4,3,5); 
        Stepper fest(SPU, 10,12,11,13); 
        void setup() 
        int what;
        void loop() {
         if (Serial.available() > 0) {
            what =;
          // open ->turn -> fix
          if(what == 1){


You can see how this works in video.

Group part:


To engrave the cube we need a 3 axis CNC. Two axes to cut the desired pattern and one to lower and raise the cutter on the cube.

The whole is to be accommodated in a stable case, therefore we have built the linkage with Macker Case. At Amazone we made threads and ordered an Arduino Motorbard and engines. Together everything cost about 100 €.

So we have built a classic CNC machine.
As we did not find a single spindle motor that could be delivered in half the time we planned with a lathe.
The parts that hold the rods and axes to the frame are 3D designed and printed. The electronics consist of an Arduino uno on which a motorboard is plugged which controls the 3 motors. All axis values for x, y and z are defined by the GCODE.

Front end and Comunication

To control the whole machine we have equipped a raspberry pi with a touch display. In Python we wrote a program on which you can choose one of 4 designs to be engraved.


We built all the parts together. It's not perfect but it's something to see. On the display you can now choose a desine.
The machine is still optimising and expandable but the week is over.

In the video you can see how one is engraved.