Kurt! It's good to hear from you and your project!
1) What stepper motor did you end up with for this project?
i ended up with a Stepping Motor Type 57BYGH310-D, CW No. 2015.05.07
2) What was the reason you were told to switch to a stepper motor? Was it because it could be positioned with more precision?
The reason we were going to go to a stepper was what you just mentioned. Since we wanted to use an IMU and a couple of Python scripts, we eventually found out that the Python script called for a stepper motor instead of the DC one that we were using.
i never could figure out the Python readings from the IMU so was unable to connect the stepper. Went back to trying to correct the glare on the LEDs and just purchased the glass jar as well as the LED tracker and put a "headband" on it and now it seems to work just fine. Maybe someday i will find someone here in town who would be interested in helping implement the IMU/Python/stepper combo. i really couldn't find anyone who could translate the DC torque into stepper torque so i was never sure that the motor i had bought was going to be able to drive the parabolas or not. It seems strong enough for at least one parabola, but for a commercial venture i was looking for 4 - 5 ganged parabolas.
The links to the project are in the previous posts: http://www.appropedia.org/Parabolic_Sol ... ter_Heater
What are you making your parabolas out of? Wish you the best of luck with your endeavour and if you have any additional questions, please feel free to ask.
With warmest greetings and have a great day!