I would like to move a stepper motor 180 degrees and back, in short intervals. With time to be determined. The application is to move rows of vertical grow towers. To grow the most lettuce in the least area, with the least energy. I need to move the towers very slowly to gather the most sun. Is there some gear reduction with code to help me accomplish this? Nema 17 or 23? I think about 80oz of torque should do it.
@Bartmanpoet, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with or advise on your project 
See About the Installation & Troubleshooting category.
Welcome to the Arduino forum and this should be an easy Arduino project, but will likely get more complex as you build it. Called "feature creep".
First, the NEMA numbers ONLY relate to the size of the mounting of the motor, nothing else. IF you are going to use gear reduction, then you need to consider the motor torque is going to be based on the increased torque from the gear reduction value.
I can also guess you want the tower to move 180 degrees, not necessarily the motor.
Have you designed the way you are going to attach the motor to the tower? Kind of important.
Are you going to move the tower all day and all night?
How are going to determine how much sunlight each lettuce plant will receive? With your design, the plants at the ends of the circle will naturally get about 1/2 the light the middle plants get?
Good luck with the design.
Paul
Least energy. = do not use steppers
Lots of DC gear motors are way more efficient.
I believe a servo motor would be a better choice. Could you help me find resources to develop sketch using millis to be able to start then stop, adjust speed and rotate 180 degrees? It should rotate slowly and stop for period of time.
I would like to rotate a row of towers, with stepper belts and pulleys (pulley sizes TBD). Servo motor mounted on the ends of rows, I think I can get 50 heads of lettuce (Or some other fast growing greens) in each tower. Then use shop air couplings to be able to remove from rows. They only have to move 180 degrees during the day. Will have to experiment with parameters to get the optimum growing conditions. In the sketch I would like to be able to adjust the speed of rotation. I would like to use millis so I can incorporate outer sensors on an I2C bus.
Then have the green house report back to me with PH, EC, ambient temp, water temp, flow and levels. Then keep reporting to me by cell, text or Email on growing conditions.
How are the plants warered?
Recirculating water?
If the plants are hanging they would be much easier to spin.
Do you have 12 volt power?
Solar or wall power?
Recirculating water in 5--6' foot lengths of hanging 4" pvc pipe towers in a row, running on 12 volts solar power with optional 110v by use of an inverter.
I would like to use a servo motor at the end of a row of towers, connected by stepper pulleys and belts. To turn towers 180 degrees, while being monitored by sensors and maintained by dosing pumps (PH, EC), floats and flow sensors. All reporting back to me using wifi, cell phone, text and email. The problem I am having is with a sketch using millis, to run the servo motor, sensors and using I2C bus, could you connect to resources to develop a sketch or any other help?
They will be watered from the top and drip down, collected at the bottom and returned to a reservoir to be recirculated.
you can get these in low RPM versions, 10 RPM
the tower needs to be able to spin easily
they are easily controlled.
every journey starts with one step.
the first step is to do the things you know and can do. Then build on that.
projects like this have both electronical and mechanical parts.
the motor and rotation of the plants is mechanical.
if you look at the water to the plants, you have a pump, maybe a water flow sensor.
That would also mean high and low switches for the resoviour.
the water flow and distribution is one complete system.
dosing is a second full and complete system, or multiple systems
and may be as simple as you pour in fertilizer in a bucket, then just dump it into the resoviour, or, since you said dosing pumps, you would need to have them each controlled separate. each dosing pump would, at the core, be one system.
water quality, PH, and whatever else, is again, a complete and separate system.
having each system controlled by a central micro is not hard.
The last system is the communication. here you have two different things.
one is having the data available as in an access point so you can get close with your cell phone, log in, then see what is happening.
or, you can have the setup connected to the network
and you can have alerts sending out alarms, or alerts.
when you put this all together, it becomes a large project, but each part is a separate one.
the questions of what have you done so far ? what parts have you been able to get to work ?
if you put each of the pieces on paper, create a schematic for each part, it would be easier to follow and you would have a full mini-project that you can get to working.
Please let us know what you have done so far.
No, it still uses power all the time, maybe not much but if the wind (draught) blows, it may use power to compensate.
You were told, a gearmotor. Use microswitches for limit switches at the ends of the 180° travel.
Mind you, this is all relative - your pump will use the most power.
Thank you! It will be inside a greenhouse, I have working sketches and wiring diagrams. For pump timer, PH, EC, Thingspeak temperature logger, PH sensing, PH logs on cell phone, EC hydroponics, Nutrient dosing system EC/ppm, pump timer, DHT 11 and LDR. The question I have is the best type of motor and it's operation (180 degrees and back, moving slowly(or in small increments)). I am looking at how to incorporate mainly the motor, while running on millis.
You have not answered my point about turning your plants only 180 degrees gives the plants at 90 degrees 2 times more sunlight than the plants at 0 and 180 degrees.
Paul
timing is easy
an encoder can provide position.
end switches also control range of rotation.
high torque gear motor, with driver and you can move 1 degree every 4 minutes. 180 degrees over 12 hours.
of course, you can rotate at the angle and time you choose.
post#12 shows a gear motor and driver.
do you have the plants on a post that can spin ?
you can create a simple test to measure power needed
I am sorry Paul, I will work that out when I have a working model.
Dave, yes I will have plants along the length of PVC. I was thinking of using a 4 inch deck post liner to get that 4th side. With 4 to 6 inch spacing, I hope that allows adequate spacing for lettuce plants.
High torque gear motor, with driver and you can move 1 degree every 4 minutes. 180 degrees over 12 hours.
Thanks for the advice Dave-in-nj