My Fanta-can traction elevator with very smooth leveling!

Having spent a whopping 5 euros on a stepper motor with gear box and darlington array driver, i started writing some software to get it working. There is an existing software library but that is a bit useless as it only drives the motor at one speed with locking function calls so it will not let the microcontroller do anything else while the motor is running. After a few hours i got the motor running with smooth acceleration and deceleration and there was enough computing power left to do full screen animation on two of the led displays you know from my previous elevator simulator/control panel.
The motor is not very powerful as it can only lift about 100 grams of stuff. That's where the traction elevator principle comes in handy. There are two loads canceling each other out, normally an elevator cab and a counter weight, but in my case i used two fanta cans filled with water. More weight means more traction and with the rope around the 'sheave' 3 times there was no slipping at all. I should have used steel cable but i had none that was thin enough to fit round the spindle so i used kite rope instead.
As you can see in the video, the motor is at 74hz per coil at top speed, giving me 148 steps of the motor per second. With just over 6 degrees per step and a 64/1 gear box i get about 1cm/sec with my 2.5 cm spindle. Not very fast but it works. I have run the motor at 92hz without problems. Any higher and it starts losing torque very fast.
With a bigger stepper motor this should be able to give a real elevator a smooth ride but i'm not going to try that. There are already multiple goods elevators running on software written by me so i know it works. It was just a bit of fun to get it working on a scale model with a stepper motor too. In real life i use a 3 phase motor with a position encoder in a closed loop but the principle is roughy the same from a software point of view.
I will probably add an animated floor indicator on the led displays and replace the fanta cans with something looking like a real elevator cab in something shafty but i don't have any detailed plans for now. Any ideas?

Thanks to Tarzan for being too lazy to bin his empty fanta cans, but only just this once! :P

Видео My Fanta-can traction elevator with very smooth leveling! канала TarzanAndConz