I was told by a friend that I could use an arduino to complete my project. Here's the project:
I built a coffee table that is connected to AC power. I have a compartment within the table that houses a video projector, which sits on a scissor jack platform (4" x 4"). The jack has a threaded rod that adjusts the height, which I wish to somehow connect to a small motor. I'd then like to be able to control the motor with the arduino controller with the push of a button or switch. So the motor needs to be able to turn the threaded rod a pre-determined number of rotations in two directions.
Start by measuring how much torque is needed to twist the shaft. That will determine the size of the stepper motor that you need. Then, get the motor and an appropriate driver. And, a switch or two.
Fabricate a mount and connector (or buy a pre-made one) to connect the stepper to the shaft and the motor to the device.
The code is pretty simple. Read the state of a switch. If it changed, step a bunch of times in one direction. Do the same for the other switch, but step in the other direction.
You are already off to a great project. Remove the knob and measure the diameter of the shaft. Find or make a pulley that can be threaded to match the rod threads. Mount the pulley just like the knob. Find a matching pulley that will mount on the motor shaft. Then measure for a belt to go around both pulleys and buy a belt to fit.
You will need a power supply suitable for the whole works. A little software and you are set to go.
A pulley (or gear) may not even be necessary if: A) As Paul pointed out, the Motor has sufficient torque. One Need for a pulley/gear is to increase torque (at the cost of Speed). B) There is enough room for the motot to be simple attached directly - shaft end to shaft end. If so, all you Need is a coupler which can also be used to compensate for different shaft sizes on the rod to be turned and the Motor itself.
