This article first appeared in
Studio Potter, Volume 4, Number 2 (Winter 1975/76).
Copyright © 1976 by Studio Potter. All rights reserved.
For many years I have been concerned that individual potters needed a better and cheaper way to mix clay than has been available. However, from my experience in making clay mixers, I realized that cost would always be a problem so long as it was necessary to power the mixer with expensive motors and large ratio, extra heavy duty gear trains. Therefore, to make the break-through in mixer cost, it was necessary to design the mixer to operate without the above.
Following is a description of just such a mixer. For obvious reasons, I call it The Anti-Establishment Mixer! It comes in two models, a rubber tired "city" version and its country cousin, the "flintstone" model. In practical use, both versions operate the same but the flintstone model requires that it be operated on dirt rather than on paved surfaces.
The secret of this mixer's low cost, yet powerful mixing action, is the elimination of both the motor and the gear train. In their place, an automobile supplies the power. The pulling action of the car causes the wheels of the mixer to turn. These, in turn, revolve the mixer paddles inside the tub. The tub does not revolve because it is a stationary part of the trailer hitch assembly.
The simplicity of this design is based on the willingness of the potter to "hitch up" his mixer to his car, add water and clay, then slowly drive in circles or take off for the local supermarket - at about 5 miles per hour. (The latter version probably would require a trailer license!)
There are only five parts which comprise the Anti-Establishment Mixer:
Making the Flintstone Wheels:
In addition to the rebar spokes, one or more layers of "hog" wire will add considerable strength to the concrete wheels. Wire it to the spokes.
Using the mixer: The capacity of the mixer is dependent on the size of the drum. A 30 gallon tub will mix about l50 pounds of dry clay. A bigger tub will handle more but additional weight must be added to the mixer so that the wheels will not slip on the ground because of increased friction. Weights can be made of stone, concrete or tanks of water, sand and junk. Experience gained from testing will determine exact batches.
Add the clay ingredients and water to the mixer. Note: the water should be between 25% and 30% of the total dry materials. After mixing several batches, the exact ratio of water to clay will be known. Pull the mixer with the car in low gear about 500 yards. Get out and check the consistency. Make adjustments as required - more water if the clay is too dry and more clay if the mix is too soft. If the wheels slip and skid, it's because the clay is too dry. It may also be because the mixer is too light and more weight is needed to overcome the friction of the plastic clay. Extra weight can be added to the frame by hanging containers of rock, sand etc.
Loading and unloading the mixer is done while the mixer is stopped. Because of its low height, clay can be removed directly from the hopper. It will also be helpful to unload part of the clay and then pull the mixer a little farther to scrape more clay from the side walls.
Because there is no differential in the axle, the mixer will tend to "jump" or "hop" around corners. Therefore, do not try to turn in tight circles.
Larger version of diagram.
Larger version of diagram.
Paul Soldner is a potter with wide-ranging interests, who divides his time between Claremont, California and Aspen, Colorado.