Spiral-Slot Dasher Churn: The Dasher Turns As It Rises and Falls

"In my second modification, Fig. X, the whole dasher rises and falls by a reciprocating rotary motion, i², i², is a tube of metal affixed to the top of the churn, and through which the shaft j², j², works freely. The tube has a spiral slot k² through it, which admits a pin l², or friction roller affixed to the staff or shaft j². This shaft is made to rise and fall by a crank motion, which from the arrangement described produces the desired effect."

Print the slotted tube upright on its flange (/uploads/blueprints/spiral-slot-dasher-churn-tube.stl): its slot turns 120° over 60 mm of rise. Print the four-bladed dasher (/uploads/blueprints/spiral-slot-dasher-churn-dasher.stl). Print in PLA at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Drill a 13 mm hole in the centre of the lid of a 1-litre wide-mouth jar and three holes for M3 screws on a 40 mm circle. Bolt the tube's flange over it with nuts and washers.

Cut a 12 mm hardwood dowel to reach from 10 mm above the jar's floor to 110 mm above the lid. Glue the dasher on its foot and pin it with a small screw through the hub's cross hole. Pass the staff up through the lid and tube, drill it across at the slot, and screw an M4 machine screw through as the pin, its head in the slot. Glue a hardwood knob on top.

Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Fill the jar no more than a third full and fit the lid. Plunge the knob steadily up and down. The slot turns the dasher a third of a turn each way as it moves. 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.

**Stephen P. W. Douglass** of Lansingburgh, Rensselaer County, New York, formerly of Pittston, received US 554, dated 9 January 1838. A crank winds up the weight; a ratchet holds it; a friction band with an adjusting screw regulates or stops the machinery. He calculated that "a weight can be raised six feet by a woman of ordinary strength or a sturdy boy ten years old in one and a half minutes or by a man in half a minute," enough for three quarters of an hour and "so as to churn effectually twenty gallons of cream." The same machine could also work a rotary dasher, an up-and-down dasher on a crank, or both at once. He claimed "the giving a rotary and vertical motion to the dasher of the churn." **Honest limits.** We work the staff by hand instead of by his weight and crank, and a printed tube stands in for his metal one. FDM prints hold food in their layer lines, so wash well and replace when worn. Your times and weights are the result.