Counter-Revolving Dasher Churn: Geared Dashers on Offset Shafts Turn Contrary Ways, Their Blades Skewed Contrary Ways

"If straight the force of the current would be around the shaft, but this is counteracted by breaking the line of the shaft, though still keeping them parallel with each other. If the blades were inclined in one direction only, then the cream would be forced to that end of the box toward which the inclination tends."

From 20 mm hardwood board make a box 700 x 300 mm inside and 300 deep; glue and screw it, and seal the inside joints with silicone sealant. Screw a hardwood pillar block E, 30 x 120 mm and 180 high, upright across the floor's middle, 340 mm from the crank end. Bore it 16.6 mm across at two points 150 mm up, 25 mm either side of the middle. Bore the crank end 17 mm across 150 mm up and 25 mm to one side, for dasher B; bore the other end 16 mm for the set screw b, 25 mm to the other side. Cut a lid to lie on top.

For each dasher cut four hardwood blades 240 x 40 x 8 mm, two hardwood hubs 36 mm across and 24 long bored 16.4 mm, and eight 12 mm dowel arms. Glue four arms into each hub a quarter turn apart, 220 mm apart along the shaft, and screw the blades across their ends 100 mm from the shaft, each blade skewed 8 degrees to the shaft (one end 31 mm ahead of the other). Skew dasher B's blades one way and C's the other.

Cut a 16 mm stainless shaft 440 mm long for B: through the crank end, through dasher B and its pinion, into the pillar block. Cut one 386 mm long for C: its pinion in line with B's beside the block, through the block and dasher C, its far end in the set screw's step. The pinions mesh 50 mm apart; pin each to its shaft. For the set screw b cut 90 mm of M16 threaded rod, drill a 16.6 mm step 20 mm deep in its inner end, run it through two nuts either side of the end wall, and fix a hardwood handle on its outer end; screw it in until C turns freely without end play. Fit a hardwood crank 120 mm long with a dowel handle on B's outer end.

Pour in about 15 litres of heavy cream at about 15 °C, checked with the thermometer, put on the lid and turn the crank steadily, timing it: the two dashers turn contrary ways. When the butter comes, lift the lid and the butter out, ladle or tip the buttermilk into a bowl, wash the butter in cold water until it runs clear, salt and weigh it.

**Aaron C. Vaughan** of Johnstown, Cambria County, Pennsylvania, US 27,396, 6 March 1860, "Churn-Dasher". He did not claim two or more dashers in one churn, nor turning them contrary ways by gearing, but the series of dashers set lengthwise, geared inside the box, each pair turning contrary ways with blades inclined contrary ways; his Fig. 2 shows three. He does not say how the contrary inclination is measured; ours are mirror images. The patent gives no sizes; every size here is ours, and our pinions are printed.