Opposed Perforated-Paddle Churn: Sloping Holed Paddles on a Geared Shaft Pass Between Paddles Sloping the Other Way on Slide Bars

"The inclination of paddles E. has a tendency to continually elevate the milk while the tendency of paddles F. is opposite and the consequence is that the milk is greatly agitated and so acted upon that the globules are rapidly broken and butter produced in an incredibly short time."

Use a 20-litre food-grade bucket as the tub A, with its bottom as C. Plane three hardwood slide bars c 330 mm long to a dovetail section, 20 mm across the inner face, 26 across the back, 11 thick. For each, cut two hardwood strips d 20 mm wide, 300 long, bevelled on one edge to hold the dovetail, and tapered behind to the bucket's wall; screw them to the wall from outside a third of a turn apart, 30 mm above the floor, so the bar slides down between them to rest on the floor. Seal the screw holes.

Chisel three slots 6 mm wide and 4 deep across the inner face of each bar, at 60, 160 and 260 mm from its foot, sloping 70 degrees from flat, all the same way. Glue the paddles F into them with food-safe silicone and a screw each, widest at the bottom, so they reach in to 70 mm from the tub's centre.

Turn a hardwood shaft D 28 mm across and 318 mm long. Set a 10 mm stainless pin 7 mm out of its foot and a 16 mm stainless rod 144 mm long 20 mm into its top. Chisel three slots through it 6 mm wide, sloping 70 degrees from flat the other way from the F paddles, at 98, 198 and 298 mm above its foot, the second a ninth of a turn and the third two ninths round from the first, and glue the paddles E in with silicone and a cross pin, so they reach 115 mm from the centre.

Cut a 12 mm HDPE lid B to the bucket's top with a 20 mm hole in the middle. Screw two hardwood ears 30 x 40 mm, 105 long, to opposite sides of the bucket's top, standing 45 mm above its rim. Cut a hardwood cross bar 370 x 140 x 25 mm, notched at its ends to drop over the ears, bored for stainless pins through ears and ends and 16.6 mm at the centre. Screw two hardwood bearing blocks 50 x 25 x 108 mm on it, one 60 to 85 mm in front of the centre and one 25 to 50 behind, bored 16.6 mm across 83 mm up. Stand the shaft on its bearing with the lid and cross bar over it, pin the pinion on its top with its teeth 30 mm above the bar, run a 16 mm stainless crank shaft 180 mm long through the blocks with the driving wheel pinned on meshing the pinion, a shaft collar, and a crank of mild steel flat bar, 100 mm throw, with a hardwood handle.

Pour about 14 litres of heavy cream at about 15 °C, checked with the thermometer, into the bucket with the paddles in, put on the lid and drop the cross bar over the ears, pinning it. Turn the crank briskly, timing it. When the butter comes, lift off the gearing and lid, draw the three slide bars up out of their strips, and turn the shaft slowly by hand so the butter gathers on its paddles. Lift it out, take off the butter, pour the buttermilk into a bowl, wash the butter in cold water until it runs clear, salt and weigh it. Before putting the bars back, push them down so any butter lodged in the grooves is forced out at the bottom.

**John R. Mickey** of Waterford, Erie County, Pennsylvania, US 31,554, 26 February 1861, "Churn". He claimed "the stationary, perforated paddles F. in combination with the rotating perforated paddles E; when the two sets of paddles (F and E) consist of simple planes, and are arranged obliquely in opposite directions", and disclaimed the tapering solid paddles of John O'Neil's rejected application of 24 June 1852. He made the churn for sweet milk and wrote that "from three gallons of sweet milk three and a quarter pounds of butter" came "in three and a half minutes"; we have not tested that, and we churn cream. He gives the paddles' slope only as "about 70"; we read it from Figs. 2 and 3 as 70 degrees from flat. He left the gearing to "any of the known ways"; ours is a printed crown wheel and pinion. Every size here is ours.