I have come up with an idea I want to build and give as a thank-you gift. I have recently become really interested in vintage/antique mechanical watches, including learning to service them and do some basic repairs.
I want to give a specific type of pocket watch as a gift (the name of the watch company has significance), however, I don't expect the recipient to carry it around with him or wind it every day, so I came up with the idea of turning it into a desk clock by building a display stand for it which would hold the watch and have some kind of mechanism to grip and turn the crown to keep the watch wound. I do not want to alter the watch itself in any way. I have some familiarity with Arduino, Eagle CAD, AutoCAD, soldering, etc., but I know very little about motors. There is a Fab Lab here, so I have access to 3D printers, laser cutters, CNC machines, etc.
My biggest concern is keeping the watch wound without overwinding it and damaging the mainspring or the winding mechanism.
As the mainspring of a watch is wound, the amount of torque that must be applied to continue winding it gradually increases. The amount of torque that would have to be applied to damage the watch should be significantly higher than what is required just to wind it. So, I want to be able to set some kind of threshold so that the motor will stop when the threshold is exceeded.
Here are some general questions I have:
Is arduino a good choice for this project? It is currently the only microcontroller I am familiar with, but would a different microcontroller or microprocessor be better?
What type of motor? I am thinking a stepper motor probably would be best, but maybe a brushless motor could work too?
Will I need a separate controller for the motor, or will the Arduino alone be sufficient?
How can I determine what the torque threshold should be?
How can I control the motor to stop when the threshold is reached? Could I just use a motor that has enough power to wind the watch but not enough to overwind it? Could I control it just by the amount of power supplied to the motor? Is there a way to sense the amount of torque being applied?
Are there other issues I should be concerned about?
I plan to build the display out of wood, but with a steel plate in between the motor and electronics and the watch to keep any magnetic fields away from the watch. I want to design it so that the watch can be easily removed and replaced in the stand, and I want to power it at a wall outlet.
I have several months yet to think about and work on this project, but I would greatly appreciate any suggestions and advice you may have! If I get it working I will definitely share my designs and code so that others can build it too.