The Anti-Establishment Mixer

by Paul Soldner

This article first appeared in Studio Potter, Volume 4, Number 2 (Winter 1975/76).
Copyright © 1976 by Studio Potter. All rights reserved.

Picture of mixer

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:

Construction:

  1. Using a cold chisel, cut a 12 inch flap out of a thirty gallon oil drum as shown in the drawing. Attention: Do not attempt to cut the drum with any flame cutters as the barrel may explode.
  2. Hammer out the flap so it will make the backboard of the mixer. Weld an angle iron to the edge of the flap to form and reinforce the tub opening. (See the illustration and/or photograph.) Cut and weld stiffeners between the back board and the tub opening. This is important structurally as it holds the back board in place during the mixing operation.
  3. Weld the 4 inch x 24 inch channel iron bearing mounts to each end of the barrel. (They act as stiffeners as well as bearing mounts.)
  4. Cut a 1 1/4 inch hole through the channel iron directly in the center of the tub. Drill and tap mounting holes for the (flange) bearing so that the shaft (1 inch x 44 inches) will pass through the center of the tub. Bolt the bearings in place, one on each side of the tub.
  5. Put the 1 inch x 44 inches shaft axle through the bearings and set the locking collars to the shaft as per instructions on the bearing box.
  6. Weld the mixing paddles to the shaft (see diagram). Make sure the paddles will clear the tub, by approximately 1/8 inch, when the shaft is rotated.
  7. Slide the wheels on each end of the shaft and weld solid to the shaft.
  8. Weld the trailer hitch assembly to the channel iron (bearing mount) located on the tub.

Making the Flintstone Wheels:

  1. Weld five 5/8 inch steel rebar spokes, 13 3/8 inches long, equidistant on a hub made of 1 inch pipe, 4 inches long. Then form a hoop of steel or rebar (28 inches in diameter) and weld to the spokes to make a wheel shape.
  2. Make a form to hold the steel reinforcing hoop square while concrete is added to make the wheel. Suggested form as follows: [see diagram, below]

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.

Mixer behind car

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.

Diagrams

Diagram of wheels
Larger version of diagram.

Diagram of tub and frame
Larger version of diagram.

Paul Soldner is a potter with wide-ranging interests, who divides his time between Claremont, California and Aspen, Colorado.