thanksgiving 2k5 : what's more excessive than a giant pie? recirculating fountains of food seemed like the obvious escalation. a custom peristaltic pump design powered by an electric drill provided a gushing torrent of delicious, piping hot gravy.
Step 1: pump design
the key component of a gravy fountain is a gravy pump. while there are a wide variety of commonly available
pumps based on impellers, these would at best cut up the giblets or even jam on thick gravy. instead we
based our design on the peristaltic pump, used, for example, to move blood without damaging the blood
cells (blood cells being analogous to giblets and blood being analogous to gravy).
six plastic rollers arrayed in a hexagon (nature's polygon) roll against a large diameter flexible hose.
pockets of gravy trapped between two successive rollers are gently transported around the circumference
and squirted out the top.
the sheet metal backing plate (leftovers from the previous thanksgiving) was left intentionally springy to
assure a good seal without precise tolerances. the tubing was glued to the backing plate with construction
adhesive providing a strong but flexible bond.
to power the pump, we used a cheap electric drill from harbor freight. this is an incredibly easy way
to add a variable speed, high torque motor to any project which mates with a wide range of shaft diameters
thanks to the adjustable chuck. we added a dimmer switch to provide better control over the motor speed
but it was ultimately run at a considerable clip. like most ac motors, the drill had relatively little torque at low speeds and tended to stall out under the pressure of 10 gallons of delicious gravy.