Churn-and-Washtub Mechanism: One Crank Works a Dasher and a Plunger and Turns Both Tubs

"It is advantageous to rotate the tubs, for by so doing if churning is being performed, the whole body of the cream will be more perfectly subjected to the action of the dasher, and if washing is being performed, the plunger will be brought in contact with every portion of the clothes."

Print two ratchet rims (/uploads/blueprints/churn-and-washtub-mechanism-ratchet-rim.stl), the churn tub (/uploads/blueprints/churn-and-washtub-mechanism-churn-tub.stl), the washtub (/uploads/blueprints/churn-and-washtub-mechanism-washtub.stl), pinion H (/uploads/blueprints/churn-and-washtub-mechanism-pinion-h.stl), wheel I (/uploads/blueprints/churn-and-washtub-mechanism-wheel-i.stl), the eccentric c (/uploads/blueprints/churn-and-washtub-mechanism-eccentric-c.stl), the cam L (/uploads/blueprints/churn-and-washtub-mechanism-cam-l.stl), the eccentric N (/uploads/blueprints/churn-and-washtub-mechanism-eccentric-n.stl), the strap O (/uploads/blueprints/churn-and-washtub-mechanism-strap-o.stl), two pawls (/uploads/blueprints/churn-and-washtub-mechanism-pawl.stl), the link b (/uploads/blueprints/churn-and-washtub-mechanism-link-b.stl), the dash (/uploads/blueprints/churn-and-washtub-mechanism-dash.stl), the dasher head (/uploads/blueprints/churn-and-washtub-mechanism-dasher-head.stl), the plunger (/uploads/blueprints/churn-and-washtub-mechanism-plunger.stl) and the crank (/uploads/blueprints/churn-and-washtub-mechanism-crank.stl). The rims need a 220 mm print bed. Print in PETG at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.

Cut a pine base 560 by 240 mm. Glue and screw two posts 40 by 18 mm and 180 mm tall in its middle, 100 mm apart inside, with a block 30 mm thick on the front post's inner face; drill 10.5 mm holes through both posts 102 mm above the base for shaft G, and through the front post and its block 150 mm up for shaft I'. Stand an 18 mm square standard a 254 mm tall 55 mm left of the middle, a post d 122 mm tall behind it, and a post 232 mm tall at the back left for the spring. Screw an M6 screw up through the base 170 mm each side of the middle as the rims' pins.

Drop a ratchet rim on each pin and stand the washtub on the left rim, the churn tub on the right. Cut 10 mm dowels 202 mm for shaft G and 148 mm for shaft I'. Thread G through the posts with pinion H, the eccentric c behind it, the cam L further back and the eccentric N on its front end; thread I' through the front post with wheel I on its inner end meshing H and the crank on its front end. Fix each with an M3 screw drilled through the dowel.

Pivot an 18 mm square pine lever G1, 243 mm long, on the standard a with an M6 screw, the link b from the eccentric's pin to its middle hole, and pin the dasher's head into its fork over the churn: a 10 mm dowel 155 mm long with the dash on its foot. Pivot the lever K on post d, its short end under the cam, and hang the plunger beside its long end on a 10 mm dowel 153 mm long, with an M3 screw through the dowel's top as the pin d. Screw a spring steel strip to the back left post, reaching over the pin. Hang the strap O on the eccentric N and pin both pawls to its foot with one M6 screw, resting on the rims' teeth at their front points.

Pour 1.2 litres of heavy cream at about 15 °C, checked with the thermometer, into the churn tub, and warm soapy water and a cloth into the washtub. Turn the crank steadily and time it with the stopwatch: the dasher and plunger rise and fall and both tubs creep round. When the butter comes, lift the dasher out, pour off the buttermilk, wash the butter in cold water until it runs clear, work in a pinch of salt and weigh it.

**Moses Swan** of Potter Hill, Rensselaer County, New York, US 21,221, 17 August 1858, "Operating Churns, &c." He combined the two tubs so that neither two systems of gearing nor two persons are needed, and claimed the arrangement of mechanism that gives the plunger and dasher their up and down motion and both tubs their rotary motion. Our crown ratchets, sizes, pine frame and printed tubs are ours. FDM prints hold food in their layer lines, so wash well and replace when worn.