This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Desiring a stirring machine for mixing photographic chemicals, I set about to design the one shown in the illustra- tion. The base and upright are made of pine, 1 in. thick, the former 8 in. wide and 10 in. long, the latter 8 in. wide and 16 in. long. A 3/8-in. slot, 12 in. long, is cut in the center of the upright, and two pieces of sheet metal or tin, 2 in. wide and 12 in. long, bent at right angles along the center of their length, are placed at equal distances, on each side of the slot, and fastened with screws. The distance between these pieces depends on the motor used, as its base should fit snugly between them.
Ill: A Self-Contained Electric Stirring Machine for Use in Mixing Photographic Chemicals
A small battery motor is purchased, and its shaft is removed and replaced with one measuring 10 in. in length. To the end of the shaft is soldered a piece of wire, bent as shown in the sketch. A bolt is attached to the center of the motor base, so that its threaded end will pass through the slot in the upright, where it is held with a wing nut. The battery cells may be placed on the back of the upright and a small switch mounted at the top and in front. - Contributed by Ray F. Yates, Niagara Falls, N. Y.