Oscillating Paddle Churn: Oblique Paddles Swung to and Fro by a Strap

"The dasher consists of an upright shaft with two or three arms I placed above each other as the size of the churn may require, passing horizontally through it in the same direction and low enough to be within the churn, to which horizontal parallel arms I I are fastened four vertical parallel boards or paddles K, two on one side of the shaft G and two on the opposite side. They are fastened to the arms obliquely at any required angle suitable for producing the intended effect."

Print the dasher standing on its lower arm (/uploads/blueprints/oscillating-paddle-churn-dasher.stl): four paddles at 45° to the arms. Print the strap drum (/uploads/blueprints/oscillating-paddle-churn-drum.stl), the double crank with its two opposite pins (/uploads/blueprints/oscillating-paddle-churn-double-crank.stl), the pivot cup (/uploads/blueprints/oscillating-paddle-churn-pivot-cup.stl) and the crank arm (/uploads/blueprints/oscillating-paddle-churn-crank-arm.stl). Print in PLA at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Join two pine sills with two cross pieces and stand two posts 330 mm tall at one end, joined at the top by a rail. Fix an arm from the middle of the rail reaching over the churn's centre. Drill both posts for a 12 mm dowel crankshaft 70 mm above the churn's top.

Set a food-safe box about 150 mm square under the arm and screw the pivot cup to its floor. Slide the dasher and the drum onto a 10 mm square hardwood shaft, drive a nail into each end as pivots, and stand it in the cup and the arm's hole through the lid. Glue the double crank and the crank arm on the dowel crankshaft. Cut two pine pitmen to reach from the crank pins to the drum. Pass a leather strip once round the drum, nail it through to the drum, and fasten one end to each pitman.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 500 ml and fit the lid. Turn the handle steadily: the dasher swings half a turn each way. 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 S. Thomson** of Luzerne County, Pennsylvania, received US 1,265, dated 27 July 1839. His frame was of timber about two inches square, with sills about eighteen inches long and posts about three feet high. A balance wheel about 2 feet across and about 16 pounds steadied the crankshaft. A 9-inch cog wheel with a crank and handle, on a shaft above, drove a 3-inch wheel on the crankshaft. "The size of this machine in all its parts may be varied and made larger or smaller as required, preserving, however, all the proportions." **Honest limits.** A food-safe box and printed parts stand in for his churn and dasher. Our handle turns the double crank directly, without his cog wheels or balance wheel. FDM prints hold food in their layer lines, so wash well and replace when worn. Your times and weights are the result.