Pendulum Twin-Dasher Churn: A Swinging Weighted Lever Rocks a Beam That Works Two Half-Dashers Alternately

"... the operator oscillates the lever L, which communicates the motion through the vibrating shaft M, the vibrating lever E, the auxiliary levers F, F', to the dasher arms G, G', thus producing an alternate reciprocating action of the dashers N, N'".

Cut a pine base A 720 x 520 mm. Stand two side pieces B B' of 44 x 70 mm timber 960 mm tall, 400 mm apart, 200 mm from the base's back edge, with diagonal side braces I I' and front braces H H' to the base. Screw top braces C C' (444 x 60 x 22 mm) across the front and back faces of the side pieces at the top, and bore both 21 mm in the middle, 30 mm below their top edge.

Screw a hardwood bearing block 80 x 80 x 18 mm, bored 20.5 mm, over each hole. Cut a 20 mm steel shaft 310 mm long and pass it through both. On its front end fix a hardwood lever E 400 x 60 x 20 mm at its middle with a bolt across, drilled 8.5 mm 150 mm each side of the middle for the pins c. On its back end fix the pendulum L, a hardwood bar 50 x 20 mm, 810 mm long, 60 mm below its top. Glue a 24 mm dowel handle h into L 180 mm below the shaft and bolt an 8 kg kettlebell to its foot as W.

Bolt a hardwood guide bar J 444 x 40 x 36 mm across the side pieces' fronts on spacer blocks so it stands 70 mm in front of them, 530 mm above the base, and cut two 27 mm square slots through it 40 mm apart. Cut two hardwood dasher arms G G' 25 mm square and 580 mm long, drop them through the slots, and drill each 8.5 mm 20 mm below its top. Cut two links F F' 30 x 14 mm with holes 282 mm apart and bolt each from a pin c on E to a pin g on an arm, with washers and lock nuts so they turn freely.

Stand a food-grade 20-litre bucket on the base under the arms. Cut two half-discs N N' 240 mm across from 12 mm plywood, each with three 34 mm holes, and screw one under each arm's foot. Cut two half-round covers m m from 12 mm plywood to fit the bucket's top, notched for the arms. Bolt a cross brace K 444 x 40 x 30 mm across the side pieces' fronts 440 mm above the base, drill it for an M8 rod 72 mm behind the arms, and run the rod through a nut in K with a wing nut on top as the thumb screw i, down onto an oblong block l laid across both covers.

Lift the front cover, pour in about 10 litres of heavy cream at about 15 °C, checked with the thermometer, put the cover back and turn the thumb screw down on the block. Swing the pendulum by its handle about 12 degrees each way and time it: the half-dashers rise and fall in turn. When the butter comes, slacken the screw, unbolt the dashers, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**James O. Merrill** of Chichester, Merrimack County, New Hampshire, assignor to Wm. A. Swain, US 23,986, 10 May 1859, "Churn". He meant it to take the labour out of churning, adapted to the strength of a child, and claimed the pendulum and weight with the shaft, beam, links and the two alternate dasher arms. He gave no sizes or weight: the frame, the 8 kg weight, the 12 degree swing and every size are ours.