Three-Roller Pin-Agitator Churn: Cream Is Crushed Between Rollers, Then Beaten by Pins Below

"The rollers are then set in motion, the effect of which is to draw in between and compress the cream, passing it through them gradually and in detail, so that every particle is subjected to an equal action, and the globules before mentioned are instantly crushed…"

Print the lower box, the upper box, three rollers standing, the agitator, the large and small pulleys and the crank. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Cut 10 mm dowels: 178 mm for the agitator, 196 mm for the middle roller and two of 162 mm for the side rollers; sand them. Pass the agitator's dowel through the lower box's end walls and the agitator, fixing it with an M3 screw drilled through. Pass each roller's dowel through the upper box's end walls and its roller, the long one in the middle, so the three rollers touch along their length.

Set the upper box on the lower. Fix the large pulley on the middle roller's dowel and the small one on the agitator's, both outside the same end, with M3 screws; tie a loop of cotton twine tightly round them as the band. Fix the crank on the middle roller's dowel outside the pulley.

Pour 1 litre of heavy cream at about 15 °C, checked with the thermometer, into the upper box: the touching rollers hold it. Turn the crank steadily and time it with the stopwatch: the rollers draw the cream down between them into the lower box, where the agitator beats it. When the butter comes, lift the upper box off, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Daniel Johnson** of New York, US 21,501, 14 September 1858. He set the rollers horizontal so the cream passes them once and is not heated by long friction, as it is between upright rollers. The tightness of his rollers could be set by placing the middle one a trifle above or below the others, and they could be geared instead of turned by friction; he allowed more rollers, more than one tier, and more or fewer beaters. He claimed two or more horizontal rollers touching or nearly touching, with a revolving dasher under them in the same box. Our rollers are fixed in place; our boxes, sizes and band are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.