Greetings, folks. I work for a chemical company, and my supervisor asked me if I could build a Drying Recorder. Now, these machines are typically very pricy, but they do not seem very complicated, and I have a good concept for building one that would meet the needs of several coworkers.
A Drying Recorder is basically an apparatus which contains a movable arm with a bunch of needles attached; and the arm moves very slowly, dragging the needles through some setting liquid (plastic, paint, etc). Based on the speed of the armature and the scratch marks made by the needles, you can tell exactly how long it takes for your liquid to dry.
More conventional models of Drying Recorders use gearboxes to achieve different rotational speeds, but I think we can take a more high-tech approach with an Arduino microcontroller in conjunction with a stepper motor. The stepper motor would turn a leadscrew, with the armature attached. The device would need to travel a constant distance in varying amounts of time, determined by the approximate drying time of the liquids we're trying to test.
Some of the test times quoted to me ranged anywhere between 4 minutes and 24 hours; so basically the Arduino stuck out as the only option which could control the motor through the turning speeds necessary to achieve these requirements.
In order to vary the speed, based on the prescribed drying times, I was thinking of hooking up a potentiometer to the final assembly and turning a dial to set your desired speed. In terms of other inputs, I would use a three-position switch to start the motion of the armature. A "forward" position on the 3-position switch would cause the stepper motor to spin the leadscrew and move the armature forward at a prescribed speed. A neutral position would be "off". Lastly, the "reverse" position on the switch would cause the motor to spin at full speed to return the armature back to its original position. Two limit switches would be incorporated at either end to make sure that the armature does not exceed the allowed limits of motion.
I will be using a 5V DC Stepper motor to drive the leadscrew. I would love some additional information about programming the Arduino (I have never used one before), some tutorials would be excellent. I would basically need to know how to hook up the Potentiometer to vary the motor speed as required by the particular drying times, as well as to incorporate the three switches (3-position, and two limit switches). I'm also interested in learning how to microstep the stepper motor through Arduino (so we get very smooth, uniform, high torque motion). The motor must be very slow, and very smooth.
If I'm not being clear enough in this original description, please let me know and I will explain more thoroughly. I would greatly appreciate any advice you guys could give me on this project. Thank you for your time.