Inclined-Shaft Piston-Wing Churn: Loose Pistons Slide by Their Weight Through Two Turning Wings

"The wings are perforated, and through said perforations pass a system of double headed pistons a a, fitting loosely and having a reciprocating movement by the action of gravity, as the shafts rotate."

Print two bevel gears, two wings, with supports under their sleeves, and twelve pistons with twelve caps. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Push a piston through each hole of the wings and glue on its cap, so it slides freely between its two heads. Slide each wing onto a 10 mm square hardwood shaft, near its far end.

In a food-grade tub about 220 mm across, fix a pine block on the floor for the shafts' far ends. Run the two shafts down from one side, 28° apart, falling about 32°, meeting at the gears near the wall; one passes out through the wall for the crank. Set the bevel gears in mesh and glue a pine crank on.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 1.5 litres. Turn the crank steadily; listen for the pistons sliding. 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.

**H. N. Mackey** of Morgantown, Monongalia County, Virginia, US 17,159, 28 April 1857. He claimed the oblique wings combined with the double-headed self-acting pistons passing through them. He wrote that the pistons cut up the currents and give friction surfaces where butter starts to form. His drawing gives no sizes; ours are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.