Rim-and-Disk Flow Churn: Cream Is Rubbed Past a Turning Disk, Then Falls Through Fixed and Turning Dashers

"The disk C, being slightly in contact with the rim X X X, as it revolves, rubs the milk or cream as it passes through ... then falling among the numerous dashers is thoroughly churned, before it passes out into the receiving vessel at the bottom."

Cut the floor out of a food-grade 20-litre bucket, leaving a 25 mm flange round the edge (a 230 mm hole). Screw two hardwood bars d d' 340 x 30 x 20 mm across under the flange, halved where they cross, and drill the crossing 10.5 mm. Run an M10 threaded rod 123 mm long up through it with a nut on top of the bars, and glue the printed thumb head on its lower end.

Screw the four rim segments inside the bucket 300 mm above the cut floor, round side inward, with stainless screws from outside. Cut 24 hardwood slats o 50 x 20 x 12 mm and screw them through the wall in three rings of eight, 80, 160 and 240 mm up, each ring turned half a space from the last.

Cut a 40 mm hardwood dowel 290 mm long for spindle B and drill an 11 mm hole 10 mm deep in the middle of its foot (the indentation). Chisel twelve mortises and glue in hardwood dashers t 82 x 20 x 12 mm, four at each of 80, 160 and 230 mm above the foot, each ring turned an eighth from the last, so they pass between the slats' rings. Glue a 12 mm stainless rod 145 mm long 30 mm into the top as spindle I. Cut disk C from 12 mm plywood, 282 mm across, and glue it on the spindle 268 mm above the foot.

Lower the spindle in so its foot sits on the thumb screw and the disk on the rim. Cut a hardwood beam R 320 x 44 x 30 mm with a 13 mm hole in the middle, slip it over spindle I onto the rim and screw two cleats under its ends inside the bucket. Fix the pinion on spindle I. Screw two bearing blocks 95 mm tall on the beam, bore them 12.5 mm 70 mm above it, and run a 12 mm stainless rod through them as shaft Q, with the crown wheel meshing the pinion and a hardwood crank K with a dowel handle on the end beyond the bucket.

Stand the churn on its bars over a clean pail or tub. Turn the thumb screw until the disk just touches the rim. Turn the crank and pour about 8 litres of heavy cream at about 15 °C slowly onto the disk, checked with the thermometer; it runs past the rim, through the dashers and into the pail. How many passes it needs is not given: pour it through again until the butter comes, timing it. Then pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Leonardo Westbrook** of New York, US 23,968, 10 May 1859, "Churn". He did not claim friction, compression or level turning dashers among fixed ones as such, only the rim with the disk working over it, with the dashers and the thumb screw. His only size is the rim, 1/2 to 3/4 in. wide. We use the plain spindle he allows instead of his cone-shaped one, and a crown wheel and pinion for his two pinions; every other size and material is ours.