Rock tumbler

thingiverse

This third-grade "Invention Convention" project involved creating a low-cost, durable rock tumbler using 3D printed parts. The project required additional materials such as a motor, drive belt, plywood, machine screws and nuts, power supply, PVC pipe, and 5/16-inch square steel. An initial design used a small DC geared motor that was deemed too weak, so they switched to a variable-speed drill motor (14.4V) with a rotary actuator for speed control. The materials list provides details on the specific components used in assembly. To construct the tumbler, they utilized inexpensive 5/16-inch square steel rod as the drive shaft and modified an old variable-speed reversible drill, adding a drive pulley to the chuck and mounting the speed control inside the box with a nautilus-shaped actuator. The rollers were made from 2-inch PVC pipes with spacer parts, fitting tightly without needing ABS glue. The entire tumbler was housed within a plywood box held together by machine screws for easy disassembly and maintenance. They purchased a 13-inch timing belt from Amazon to drive the tumbler but later concluded that a longer one would be more beneficial. Motor clamps were used to provide tension on the pulley.