Roller-and-Concave Churn: Cream Falls Between a Turning Roller and an Adjustable Concave, Then Onto a Dasher Below

"The milk is next to be poured into the receiver T; and through the aperture or slot formed in its bottom, the milk will fall into the angle between the cylinder and concave; and in passing between the same, the globules of cream will be crushed, spread or flattened or torn apart and caused to fall into the reservoir, H, when by being acted on by the dasher, they will readily be collected in a mass or into masses."

Cut 400 mm of food-grade PE pipe 250 mm across with a 10 mm wall and saw a 110 mm opening along its top. Cut two HDPE ends to fit, bored 16.6 mm on the axis; bore one 20 mm, 100 mm below the axis, and fit the spigot as the outlet W. Seal the ends in with silicone sealant. Make a hardwood frame round it: base, two sides, two ends bored for the shaft, a cradle under the pipe, and bars B and C along its top edges. In one end cut a chamber 24 x 100 mm down to the pipe's end for the thermometer's probe.

Fix two hardwood crosses, each two arms 210 x 30 x 20 mm, on a 16 mm stainless shaft 15 mm in from the reservoir's ends, and screw four hardwood slats 20 x 20 mm, 390 long, across their ends 85 mm from the shaft. Pass the shaft through the ends, with the gear F outside the frame's end, held by collars.

Make a hardwood case 424 x 180 mm and 150 deep, open at top and bottom, with two sloping boards inside its foot leading down to a 90 mm opening, to sit on bars B and C. Bore its ends 12.6 mm, 75 mm above its foot, for a 12 mm stainless shaft M carrying the roller; cut a slot 18 x 24 mm in each end beside it for the concave's ends. Cut a hardwood concave 398 x 22 x 60 mm, hollowed on one face to 74 mm across, with tongues on its ends in the slots. Run a 70 mm length of threaded rod through a nut in each end of the case against the concave's back, with a wing nut on the outside as the thumb screws Q and R, and set the concave 2 mm from the roller. Fit the wheel N on the shaft's outer end with a dowel handle O in its face, meshing gear F. Hold the case down with hooks and eyes.

Make a hardwood trough to sit on the case, its bottom two boards sloping to a V, with a slot S 300 x 6 mm along the V right above the gap between roller and concave. Fit a lid U with a knob.

Put the thermometer's probe in the chamber m against the reservoir. Start turning the handle, then pour about 6 litres of heavy cream at about 15 °C into the trough a little at a time, timing it; it runs through the slot, between the roller and the concave, and down onto the dasher. Keep turning until the butter gathers. Draw the buttermilk off at the outlet into a bowl, lift off the trough and case, take out the butter, wash it in cold water until it runs clear, salt and weigh it.

**Reuben G. Holmes** of Worcester, Massachusetts, US 28,177, 8 May 1860, "Churn". He disclaims squeeze rollers over a dasher in one chamber (US 21,001), a concave working with a reservoir, a dasher against a concave, and US 23,968, and claims his churn as a whole, with roller and concave in their own chamber above the dasher's. He says butter comes "in three or four minutes". His reservoir's sides are metal; ours is PE pipe, and every size is ours.