If you have an old electric typewriter lying around - do not rush to throw it away. Through a small alteration, you can make her a fun toy for children - a drawing machine. Unfortunately, the master did not leave a complete description of the alteration process, all in general terms.
Let's see an example of how this device works.
So, for his project, the master used the old Smith Corona electric typewriter.
Still, the typewriter is intended for writing, and there were large gaps when drawing. The master solved this problem by installing a gearbox from an old scanner. The paper feed mechanism does not need to be redone; everything works quite smoothly.
Now for the software. I am writing, as the author describes, with a slight adjustment.
Here is what I use:
Arduino UNO is running GRBL (version 1.1g, I think).
Expansion board for Arduino CNC with A4988 engine drivers.
12V power supply
Program for controlling CNC machine Universal G-code Sender (UGS).
Added some limit switches for safety.
The last image shows the GRBL settings that I entered / updated through UGS.
To install the pen and move it up / down, the wizard used an old DVD drive.
I disassembled it leaving only a frame, guides and a metal object between them that hold the lasers.
Pasik is connected to a small disk, which initially set in motion a gear wheel. He just mounted the pasik on the disk. This motor is used as a servo, that is, it moves back and forth about 90 degrees, stretching and releasing the string.
It would be much easier to use a real servo, but since GRBL is configured for stepper motors, he just thought it was easier.
Then he adjusted the move step in the UGS software so that the writing pen moved as it should. A small spring retains slight tension on the handle.