Toggle-Lever Churn: A Crank Crooks and Straightens a Jointed Lever, Rocking a Walking Beam Twice Each Turn

"One end of the walking beam is connected with a toggle jointed lever, the lower end of which lever is connected with a shaft that turns or rocks in the ends of the sills A, A, see letter F F." ... "I now come to the operation, which is simply to turn the crank H, which will alternately crook and straighten the toggle jointed lever causing the dasher to move up and down twice to one revolution of the crank."

From pine lumber cut two sills 80 x 100 mm, 1250 mm long, and lay them 400 mm apart, centre to centre. Let three cross ties 80 x 30 mm into their tops: one under the churn's place near one end, one in the middle, one 100 mm in from the far end. Screw a board 340 x 300 mm on the end tie, between the sills, for the churn to stand on. Let two posts C, 60 x 60 mm, into the sills either side of the churn's place, reaching 560 mm above the floor, and two posts D 650 mm along from them, reaching 760 mm. Bore the posts D 17 mm across, 650 mm above the floor, for the beam's pivot, and the sills' far ends 21 mm across, 60 mm above the floor and 50 mm from the ends, for the rocking shaft.

Cut a hardwood beam 40 x 60 mm, 1010 mm long. Cut a slot 28 x 80 mm through it 30 mm from one end for the staff, and bore 12.8 mm across that slot. Bore 16.8 mm across 650 mm from the slot's centre for a 16 mm stainless pivot through the posts D, and 12.8 mm across 300 mm beyond the pivot for the toggle's pin. Glue a 22 mm hardwood staff into the dasher's socket so its top is 459 mm above the dasher's underside, and bore it 12.8 mm across 414 mm up from the underside; pin it in the beam's slot with a 12 mm stainless pin and split pins.

Pass a 20 mm stainless rod through the sills' far ends as the rocking shaft. Cut four hardwood links 15 x 40 mm, each with two 12.8 mm holes 320 mm apart: a pair of lower links on the rocking shaft, and a pair of upper links on the beam's end pin, either side of the beam. Join the four at the knee with one 12 mm stainless pin, the upper pair inside the lower pair, leaving the middle free for the connecting shaft. Secure every pin with split pins.

Screw a hardwood bar G 25 x 60 mm along the outside of each side, from post C to post D, 400 mm above the floor, and bore both 20.8 mm across 378 mm from the posts C. Cut a 20 mm stainless crank shaft 610 mm long, through both bars and 85 mm beyond one. Build the crank in the middle: two hardwood webs 30 x 14 mm, glued and pinned to the shaft with a 32 mm gap, carrying a 12 mm stainless crank pin 150 mm out; cut the shaft away between them. Outside the bar fit a hardwood arm 130 mm long with a dowel handle. Cut a hardwood connecting shaft I 30 x 40 mm with 12.8 mm holes 600 mm apart, from the crank pin to the knee pin. Fit collars either side of the bars.

Bore a 48 mm hole in the centre of the bucket's lid for the staff. Bend two hooks from mild steel flat bar to reach from the posts C over the bucket's rim, and fasten each to its post with a carriage bolt and wing nut, as the patent's hooks are "provided each with a bolt and nut and fastened to the posts C".

Lift the beam's dasher end, stand the bucket on its board with about 10 litres of heavy cream at about 15 °C, checked with the thermometer, lower the dasher in, put on the lid over the staff and fasten the hooks. Turn the crank steadily, timing it. When the butter comes, unhook the bucket, lift the dasher out, pour off the buttermilk into a bowl, wash the butter in cold water until it runs clear, salt and weigh it.

**Edwin B. Clement** of Barnet, Caledonia County, Vermont, US 27,205, 21 February 1860, "Churn". He claimed "the arrangement of the toggle joint F, walking beam E, crank H, and connecting shaft I". The patent gives no sizes and does not show one post C; every size here is ours, as are the bucket, the cone dasher, the paired links and the built-up crank.