Rotary Stirring Churn: Three Floats That Stop the Cream Merely Going Round

"To the long end of the arm I attach firmly a perpendicular float (n, Fig. 2,) its outer edge being parallel to the sides of the churn and reaching nearly to the bottom being in width about one third of the length from the shaft to the end of the arm to which it is attached, and placed in such position that the side of the float would form an angle of about forty five degrees with a line drawn from its inner edge to the center of the lower shaft."

Print the rotor upside down on its arm (/uploads/blueprints/rotary-stirring-churn-floats.stl): the arm with the long 45° float, the curved float at the shaft and the angled float on the short end. Print the foot socket (/uploads/blueprints/rotary-stirring-churn-foot-socket.stl), the top bearing (/uploads/blueprints/rotary-stirring-churn-top-bearing.stl) and the crank arm (/uploads/blueprints/rotary-stirring-churn-crank-arm.stl). Print in PLA at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Bed the foot socket in the centre of a stock pot's floor with silicone. Screw the top bearing to a pine batten laid across the pot's rim, its hole over the socket. Cut a lid from plywood in two halves with a 40 mm hole where they meet, for air, as his two lids.

Cut a 10 mm square hardwood shaft from the socket to 30 mm above the bearing. Slide the rotor on so its floats clear the floor, glue it, stand the shaft in the socket and through the bearing, and glue the crank arm and a dowel handle on top.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 1 litre, fit the lid halves, and crank steadily; 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.

**Roderick Goodwin** of North Bergen, Genesee County, New York, received US 2,603, dated 4 May 1842. His frame's two posts went into loops on the tub, held by thumb screws, so it could be raised, lowered or taken off; the upper and lower shafts joined by a square tenon and socket; the whole could be wood, or partly wood and partly iron or other metal, and "can be separated in a moment for the purpose of cleaning." He claimed the shape, position, arrangement and relative situation of the floats on the arm. **Honest limits.** A stock pot, a batten and printed parts stand in for his tub and frame, and our crank turns the shaft directly, without his mitred wheels. FDM prints hold food in their layer lines, so wash well and replace when worn. Your times and weights are the result.