Cam-Wheel Crosspiece Churn: Free Cam Wheels Above and Below the Arm Throw the Cream Out and Draw It Back

"The lower camwheels will greatly facilitate the centrifugal motion of the cream, and the upper camwheels will facilitate the motion of the cream toward the center, thereby diminishing the whirling motion that the cream would have if the camwheels were not used."

Print the crosspiece, four cam wheels, pinion I, wheel J, the step, the cover, two posts, the support and the crank. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Cut a 10 mm square hardwood strip 284 mm long as the shaft and sand it. Slide the crosspiece on, its hub 24 mm above the shaft's foot, and fix it with an M3 screw drilled through the shaft. Put an M4 screw up through each of the four pin holes: two cam wheels go on the outer pins on top, two flipped over on the inner pins below, each held loosely by a lock nut so it spins freely. Set the step in the pot and stand the shaft in it.

Lay the cover on the pot with the shaft through its centre. Fix pinion I on the shaft with an M3 screw drilled through it. Screw the support over the shaft's top and the two posts to the cover from below, M4 screws in all. Push a 10 mm dowel through the posts as the crank shaft, press wheel J tight on its inner end to mesh with I, and fix the crank on its outer end with an M3 screw drilled through the dowel.

Pour in 1.5 litres of heavy cream at about 15 °C, checked with the thermometer. Turn the crank steadily and time it with the stopwatch. When the butter comes, lift out the cover and shaft, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Alfred Rose** of Penn Yan, Yates County, New York, US 20,730, 29 June 1858. His box was square, of wood or metal; his lid came in halves held by latches; his posts had feet to fit any size of churn. He claimed the cam wheels E, E and F, F and the crosspiece D, arranged as shown. Our pot, cover, sizes, gear counts and the cam wheels' outline are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.