Hi Barry,

But yes of course! I was so focused on modeling that I didn't bother to seriously study how it worked.
Oh dear! at my age...!?!/###/!?!
Well, the screw is not an Archimedean screw. It is, as you say, an "elevator screw". The Archimedean screw is tilted (dixit Wikipedia)

Barry> the screw turns the hourglass is motionless.
In Albert Karlen's original hourglass, the screw is integral with the support (notches on the upper and lower parts of the screw). So would there still be a design problem?

But in fact, it may be a prayer wheel for an unknown deity!

- Zooen