Hi there,
I have been printing 3d clocks for about a year now all of which I have designed and built from first principles, most of which have been electric using Arduino Nano, and the 28BYJ-48 stepper. All have been working fine. However, the stepper motor used is not very accurate and giving +or- one min in 24hours.
I have recently downloaded the files for Steve's SP5 I must say the documentation is excellent.
I will download the SP6 in the next few days but i have one question for Steve. What is the best stepper motor to use as there are many nema 17 motor to choose from?
Would i be correct in selecting model # 17HS 13-0404s1. to run the SP6 ?
Any help and advise would be much appreciated
Many Thanks
Alan
I just updated the links at https://www.stevesclocks.com/sp6 to include better references pointing to the controller. Refresh the page and download the CNC Shield V4 Addendum showing the full details on how to build the controller using parts from Amazon. Eventually, I designed a smaller custom board. There is a link to Etsy for the new controller with options for bare boards or fully programmed and ready to plug in to the clock.
Steve
Hi Alan,
Stepper motors are perfect for driving a clock because if the motor is rated at 200 steps per revolution and you give it 200 steps then it will rotate exactly one revolution. A clock needs so little power that it is very difficult to overload the motor so it will miss a step. Any time error might be caused by the reference clock timing. That is why I started using a DS3231 precision time base in my "Silent Shield Clock Controller". It has an accuracy of around a minute per year.
The SP6 clock was originally designed with a custom resistor based stepper motor driver. It needs to use a stepper motor with 30-ohm coils like the one you referenced. It also uses the built-in Arduino Nano time reference that needs to be manually calibrated for each clock. However, the old controller has been upgraded to the significantly easier to use and more accurate silent shield clock controller.
I strongly recommend using the new controller. It uses the more common stepper motors with 2-3-ohm coils. One example is 17HE12-1204S. The key features are 2-3-ohm coils and a 4-pin straight header (usually black) on the controller end. A connector at the motor end is nice, but not required. The default algorithm for SP6 expects a 200-step motor, which is the most common. The crazy gear clocks are slightly quieter with 400-step motors, but also support 200-step motors.
Steve