Spiral-Beater Box Churn: Diamond-Holed and Hollow-Ended Beaters Drive the Cream End to End

"... the base of said beaters being made small and narrow where they enter the shaft in order to form an opening for the passage of the cream, between each of the beaters, while the holes in each alternate beater form another passage".

Use a food-grade container 400 x 280 mm inside and 250 mm deep, with a rim. From 18 mm pine cut two ends 362 x 750 mm with a 120 mm arch at the foot, two sides 444 x 630 mm, two rails 444 x 40 mm and a shelf 444 x 326 mm. Screw the sides between the ends, the rails inside the sides 3 mm below the top, and the shelf 200 mm up. Cut a 360 x 272 mm opening in the front side above the shelf and hang a 356 x 268 mm pine door in it on two butt hinges along its bottom edge.

Hang the container by its rim on the rails. Drill a 17 mm hole through both pine ends and both container ends, 150 mm above the container's inside floor. Cut the stainless tube (16 mm) to 574 mm and push it through. Slide on the seven beaters, B, C, B, C, B, C, B, 50 mm apart from the middle out, each a quarter turn round from the last, all blades turned the same way, and fix each with an M4 screw across hub and shaft. Fit the collar on the far end and the crank on the near end with M4 screws, and glue a 12 mm dowel 114 mm long into the crank as the handle.

Bring the cream to about 15 °C: in warm weather set a tray of ice in the chamber under the box, in cold weather a tray of warm water, and shut the door. Pour in about 12 litres of heavy cream, keeping it 20 mm below the shaft, and check it with the thermometer. Turn the crank steadily and time it. When the butter comes, lift the container out, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Harry Robie** and **Royal V. Robie** of Eaton, Madison County, New York, US 22,090, 16 November 1858, "Churn". They knew beaters set spirally round a level shaft were old, and claimed only the diamond-holed beater B with the hollow-ended beater C and the passage under their narrow bases. They gave no sizes or materials and no number of beaters: ours are seven at 50 mm and a quarter turn apart, blades turned 30 degrees. Their box (Fig. 1) has a rounded floor; our container is flat.