Radial-Roller Spiral-Shaft Churn: A Ring of Cone-Pointed Rollers Turning Both Ways Round a Spiral-Winged Shaft

"By turning the central roller C, rapidly, the cream is dashed by the action of the flanches against the inside of the encircling rollers A, A', which are at the same time set in motion in the direction indicated by the arrows, thus pressing the milk or cream between them as it passes from the inside space a, within the circle of rollers A, A, into the space b, outside of the same."

Print four driven rollers with their pinions (/uploads/blueprints/radial-roller-spiral-shaft-churn-roller-a.stl), four plain rollers (/uploads/blueprints/radial-roller-spiral-shaft-churn-roller-a-prime.stl), the spiral shaft (/uploads/blueprints/radial-roller-spiral-shaft-churn-spiral-shaft.stl), the spur wheel with its crank arm (/uploads/blueprints/radial-roller-spiral-shaft-churn-spur-wheel.stl), the top frame (/uploads/blueprints/radial-roller-spiral-shaft-churn-top-frame.stl) and the floor plate (/uploads/blueprints/radial-roller-spiral-shaft-churn-floor-plate.stl). Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Build an open pine box about 174 mm square inside and 190 mm deep. Glue a 10 mm pine strip along two opposite walls, their tops 177 mm above the floor, for the top frame to rest on. Lay the floor plate in the bottom: its eight conical seats take the rollers' cone points and its centre hole takes the shaft.

Stand the spiral shaft in the centre and the eight rollers round it, driven and plain in turn, so each touches its neighbours. Drop the top frame over their journals onto the strips, then fit the spur wheel on the flat at the shaft's top so it meshes with the four pinions.

Pour in 1 litre of heavy cream at about 15 °C, checked with the thermometer, to below the top frame. Turn the crank steadily and time it with the stopwatch: the wings throw the cream outward through the rollers and it returns under them between the cone points. When the butter comes, lift out the frame, the rollers and the shaft, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**James MacNish** of Berlin, Marquette County, Wisconsin, US 20,025, 20 April 1858; reissued 30 November 1858 as No. 630. The drawing sheet spells the name McNish. He showed smooth rollers as best for churning milk, a corrugated roller for thin cream and a fluted roller for thick cream, and held all the rollers in an iron frame at the top. He claimed the central spiral-winged shaft with the circle of rollers, some turned directly one way and the others indirectly the opposite way. Our sizes, gear counts and printed frames are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.