update 2(2016/11/25) added printable spacers and a motor mount plate for 20mm npm motor
update 1(2015/2/6) : added assembly sequence sheet .
this is a simple clock based on a single geared stepper motor which i found in surplus 10 for a dollar... The motor is basically a 1:30 geared motor working at 12v with a 3mm shaft. The single motor is driven by a attiny2313 and l293dd circuit with the coded written in arduino ide. The single motor moves a gear train which in turn moves the minute ring and hour ring. The attiny pulses the motor every minute to move the minute wheel and the hour wheel.
print all the parts at minimum 0.2mm layer height
bolts : m3 x 45mm 4
m3 x 25 mm 2
m3 x 22 mm 1
m3 x 10 grub screw for motor gear
m3 nut x 7
for npm motor (optional)
m2 x 10 2
m2 nuts 2
for bj25 / bj20 motor
m3 x 15 self tapping screws 2
pcb spacers / cut from any brass/copper tubing ( printable option also )
4.5 outer dia x 3.5 mm inner dia x 12.mm length 2 pieces
4.5 outer dia x 3.5 mm inner dia x 8.5.mm length 4 pieces
4.5 outer dia x 3.5 mm inner dia x 6.5.mm length 2 pieces
for the stepper you can use any 20mm or 25mm diameter geared more than 1:10 ratio, bipolar or unipolar.