Air-Pump Annular Dasher Churn: A Pump in the Middle, a Ring Dasher Round It

"Within the cylinder a bucket or piston (b) is fitted in the manner of a common pump, but with the valve (b') of the piston opening downward, in order that when the piston rises the air may pass down through it into the lower part of the cylinder to be forced out through the valves (e e e e) around the bottom of the cylinder into the surrounding cream when the piston is depressed."

Print the pump cylinder upright on its base (/uploads/blueprints/air-pump-annular-dasher-churn-pump-cylinder.stl), the piston (/uploads/blueprints/air-pump-annular-dasher-churn-piston.stl), the ring dasher with its eight arms (/uploads/blueprints/air-pump-annular-dasher-churn-dasher.stl) and the crosshead (/uploads/blueprints/air-pump-annular-dasher-churn-crosshead.stl). Print in PLA at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Cut a strip of thin leather and glue it round the outside of the cylinder along its top edge only, over the six ports near the foot, so it lifts to let air out and closes against cream. Cut a leather disc to lie on top of the piston over its four holes, held at the centre by the rod, so air passes down but not up. Fit a leather cup washer in the piston's groove.

Screw the cylinder's base to the centre of a food-grade bucket's floor, sealed with silicone. Thread an M8 rod through the crosshead and piston with nuts, slide the ring dasher over the cylinder, and join it to the crosshead by two 4 mm steel rods. Stand a pine post beside the bucket, pivot a pine beam on it, and hang the crosshead from the beam's end so a hand on the other end works piston and dasher together.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 1.5 litres, enough to cover the ports. Work the beam steadily; bubbles should rise on each down-stroke. Time until the butter comes. Pour off the buttermilk, add cold water, churn a little and pour off again until it runs clear; work in a pinch of salt and weigh the butter.

**Stephen Ballard** of Meigs Creek, Morgan County, Ohio, received US 5,567, dated 16 May 1848. The cylinder was held to the bottom by a button, screw or other means for ready removal; the machine could be worked by "manual, dog, water, or other power." He wrote that the air acts "chemically by imparting its oxygen to acidify the cream"; that is his explanation, not a measured fact. He claimed "the combination of the reciprocating annular dasher and air pump with the tub or barrel to contain the cream." **Honest limits.** A bucket and printed parts stand in for his tub and pump, and a hand beam for his cog wheels, balance wheel, crank and pitman. FDM prints hold food in their layer lines, so wash well and replace when worn. Your times and weights are the result.