Laser cut clock reminds us of a Spirograph
posted Sep 21st 2011 4:01pm by Brian Benchofffiled under: clock hacks
[Brian] from Louisville’s LVL1 hackerspace sent in this laser cut gear clock that’s almost unlike any other clock we’ve seen before. [Brian] also put up a wonderful Instructable for his build.
Since LVL1 got a better laser cutter a lot of neat projects have been piling up. [Brian] based his clock around two cheap stepper motors driven by a freeduino. A chronodot was used to keep accurate time. Making the gears, though, presented a few problems. While prototyping the gear clock face, it was apparent that the numbers should be oriented along a line coming from the center of the gear. The prototype also used 100 teeth and that didn’t translate well into a clock design. [Brian] designed the minute gear with 60 teeth, and the hour gear with 144 teeth so that each tooth would equal 5 minutes.
[Brian]‘s clock is functionally similar to this $2500 gem, and certainly much less expensive even after the cost of the laser cutter is taken into account. Of course, the Spirograph clock keeps track of minutes so it may be worth upwards of $5k.
I saw this the other day and realized that, with the right gearing calculation and combination of stepper motor and a simple stepper IC, the Arduino wouldn’t be needed at all.
You could use the 1pps output of the ChronoDot to generate a temperature-compensated accurate pulse train which you would provide to the stepper driver IC. The IC would rotate the motor at a precise continuous rate. Now you need to settle on a motor step count and ring gear ratio that rotates the ring once every 43200 pulses.