[Lab] Arduino Day and some great advice!

[Adrian]

Dear all,

Some of you were involved in a discussion about my new clock - TIME WEIGHTS
- during Arduino Day. 
The new clock - TIME WEIGHTS - displays the time (hours, minutes and
seconds) using three brass weights. The weights are driven in a looped
configuration with three servos, three pulleys and GT2 timing belt and a
couple of pulleys. As the length of the belt changes with the displayed
time, I needed a means of "spooling" the excess belt, while also playing it
out on demand.

As I mentioned yesterday, I have been struggling with the spooling system...
I have tried using a brushless motor but it had insufficient torque. I then
tried a servo modified for continuous rotation but only succeeded in
stripping the gears as the torque from the stepper pulling on the servo was
too great!

Dave, You're a genius!  
Following your advice, I tried using an old tape measure mechanism to rewind
the timing belt (similar to what I used in the LENGTH OF TIME clock) and the
spooling works beautifully.
Therein lies the power of community!!

Video to come!

Bye the way, does anyone have any A4988 Stepper Driver Modules that they
could lend me? 
I've been using the DRV8825 Stepper Motor Drivers and they are really
problematic.
I have 10 on order but do not expect them for a couple of weeks.

Many thanks, 

... Adrian