Rack-and-Segment Crank Churn: A Crank Rocks a Toothed Segment That Drives the Dasher Up and Down

"This is a simple device and a good length of stroke with a quick speed may be given the dasher K, and by a very direct means so that not much power can be lost by friction."

Print the frame, the lid, wheel E with its crank, pinion F, the crank pulley, the segment, the rack, the rod and two dashers. The lid and frame need a 240 mm print bed. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Bolt the frame upright on the lid with two M4 screws, washers and lock nuts. Glue a 10 mm dowel into the boss for wheel E, standing 16 mm out in front, and one into the boss for the segment, standing 14 mm out behind. Drill a small pilot in each dowel's end.

Push pinion F's axle through the curved bar from the front, slide the crank pulley onto its flat behind, and fix it with an M3 screw and washer in the axle's end. Put wheel E on its dowel, meshing with F, held by an M3 screw and washer through the hole in its crank arm; put the segment on its dowel, held the same way. Slide the rack into the guide with its teeth toward the segment. Join the crank pulley to the end of the segment's curved arm with the rod, using M6 screws and lock nuts.

Cut a 10 mm square hardwood strip 231 mm long as the dasher rod and sand it. Fit one dasher at its foot and the other about 86 mm higher, each fixed by an M3 screw through its boss, drilled through the rod. Stand the rod in the pot, set the lid on with the rod through its square hole, and screw the rod into the rack's socket.

Pour in 1 litre of heavy cream at about 15 °C, checked with the thermometer. Turn the handle steadily and time it with the stopwatch: the dashers rise and fall four times for each turn. When the butter comes, lift the lid and dashers out, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**G. S. Rarey** of Columbus, Franklin County, Ohio, US 20,089, 27 April 1858. His case was a wooden box of any proper size, its lid hooked down to it; the frame could be cast of metal in one piece. His dasher was two plates or boards notched to form projecting arms. He claimed working the dasher up and down from the wheel through the pinion, crank pulley, connecting rod, segment and rack bar. Our pot, sizes, gear counts and printed parts are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.