[SML] Hovercraft revolve?

[Dougherty, Jim]

We did a marble revolve once.  Only 5¹ diameter and the marbles ran in two
races - one near the edge, the other a bit of the way in.  I¹d say we
carefully calculated the separation distance to ensure equal loading
throughout, but that would be an alternative fact.  It worked ok - low
profile, spun easily with the one person load it was intended for.  We
built it out of Baltic birch ply, so no seams, with the races formed with
a core box bit in a router in a jig.  However, it was loud and finicky -
if you don¹t get the tension on the center pivot bolt right, it¹s either
too tight to turn or the marbles jump their races.  Quality control at the
marble factory isn¹t what it once was - diameters can vary.

Chasing marbles around the shop, however, is a blast.

- Jim Dougherty
ATD, Middlebury College Theatre Dept.