Alternating Rocking-Leaf Churn: Half-Cogged Wheels Reverse the Agitator, a Spiral Rocks Its Leaves

"D, operating shaft, to which are secured the wheels F, F', partially cogged on their inner faces, so that the gear of one will engage the pinion p on head of main shaft, at the moment the said pinion leaves the teeth of the other wheel, the number of cogs on each wheel being sufficient to insure the entire revolution of the pinion p"

Print two half-cogged wheels, the pinion, the spiral cap, the agitator hub, four outer leaves, the rod head and the step. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Cut a 16 mm pipe about 345 mm long and saw a slot down it where the hub sits and one at the top for the arm. Glue the hub low on it and pin the outer leaves at their middles to the hub's lugs with 3 mm rod. Glue the head on the foot of a 4 mm rod, bend its top into a short arm, and drop it in the pipe with the arm out through the top slot; run spring wires from the head through the slots to the leaves' feet.

Stand the step in a food-grade container about 170 mm across, wider at the foot, and the pipe in it. Make a pine lid with a bridge, slide the spiral cap down the pipe so the arm enters its groove by the straight channel, screw the cap on the bridge, and glue the pinion on the pipe's top. Run a 10 mm square shaft in two standards, a wheel each side of the pinion, cogs opposite, and a crank.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 1.5 litres. Turn the crank steadily one way; the agitator turns, stops, turns back, and its outer leaves rock. 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.

**John G. Dungan** of Steubenville, Jefferson County, Ohio, US 13,638, 9 October 1855. He claimed giving the outer leaves of an alternately opposite rotating agitator a rocking motion to and from the sides of the churn. He suggested covering the shaft's slots with slides, and rigid jointed rods instead of spring rods. Our sizes, tooth counts and 20 mm climb are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.