I had this turntable before (made from a giant old precision potentiomenter) -- which goes round from a miniature gearhead motor and a rubber roller bearing on the large gear. It is very smooth and steady. But here it is setup for gigapans -- with a a levelling head, and Manfrotto rotator (for rapid prepositioning) and a manual on/off switch for the motor and a wireless release for the camera.
Sometimes I stick my Android phone running an inclinometer app on the extended perspex bar the camera is mounted to. The bar also serves as a lever to position the tilt -- via the markings on the Gitzo rotator gadget the arm is bolted to.
Heavy cameras start and stop rotating smoothly and quickly on it.