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Twin-Plunger Air-Chamber Churn: Two Plungers Throw the Cream Through a Middle Chamber
Andrews made the cream do the travelling, back and forth through a middle chamber.
John Andrews of Middlesex County, Massachusetts, received US 7,298, dated 23 April 1850, for a churn box divided by two vertical partitions into three apartments, with a series of holes "at or near its bottom" in each partition, "unprovided with valves." Each outer chamber has a plunger on a rod jointed to a brake, "one of the said plungers being elevated while the other is being depressed," so the cream is thrown "back and forth in several streams through the air chamber." Holes near the partitions' tops let air in under each rising plunger.
This rung works out the streams, then prints the partitions and plungers, builds the box and brake, and makes butter.
Intermediate
About 5 hours, plus printing
Instructions
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The streams
The streams
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Two dashers worked oppositely by one lever before it
Two dashers worked oppositely by one lever before it
The embedded blueprint works two dashers in one churn from a lever. Andrews puts each plunger in its own chamber so the cream must flow between them.
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Read US 7,298
Read US 7,298
"Through each of the partitions a, b, and near the upper part thereof, I make one or more holes d, d, d, &c., as seen in Figs. 2 and 3, they being so arranged that the plunger F or F', during its upward stroke, shall pass partially or wholly above them, and in order to allow air to rush through said hole or holes and into the space directly under the plunger. The descent of the plunger forces such air into and through the cream."
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Print the parts
Print the parts
Print two partitions (/uploads/blueprints/twin-plunger-air-chamber-churn-partition.stl) with their foot holes and air holes, two plungers (/uploads/blueprints/twin-plunger-air-chamber-churn-plunger.stl) and the brake hub (/uploads/blueprints/twin-plunger-air-chamber-churn-brake-hub.stl). Print in PLA at 0.2 mm layers, 30 % infill, 4 walls; wash before first use.
Materials for this step:
PLA Filament1 pieceTools needed:
FDM 3D Printer5
5
The box
The box
Take a food-safe box about 230 × 120 × 160 mm. Glue the two partitions across it in silicone, dividing it into three equal chambers.
Materials for this step:
Food-Grade Storage Container1 piece
Silicone Sealant1 pieceTools needed:
Clamps
Tape Measure6
6
Plungers and brake
Plungers and brake
Glue a 12 mm hardwood dowel rod in each plunger. Screw two pine standards to the box's middle, pass a dowel through them as the rocker shaft, and fix a pine brake across it with the hub. Join each rod to an end of the brake on a loose screw, so one plunger rises as the other falls.
Materials for this step:
Hardwood Dowels1 piece
Pine Board1 piece
Machine Screws1 piece
Hex Nut1 piece
Wood Glue1 piece
#8 x 1" Wood Screw1 pieceTools needed:
Hand Saw
Cordless Drill
Drill Bit Set
Screwdriver Set7
7
The build in 3D
The build in 3D
FreeCAD model of this build, not of the patent: the box cut away to show the two partitions with holes at foot and top, the plunger in each outer chamber, one up and one down, their rods and the rocking brake on its standards.
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Rock the brake and make butter
Rock the brake and make butter
Let the heavy cream stand until it reaches about 15 °C, checked with the thermometer. Pour in 1.5 litres, below the top holes. Rock the brake steadily up and down; time until the butter comes. Pour off the buttermilk, add cold water, churn a little and pour off again until it runs clear; work in a pinch of salt and weigh the butter.
Materials for this step:
Heavy Cream1500 ml
Coarse Sea Salt1 piece
Water1 pieceTools needed:
Leave-In Probe Thermometer
Stopwatch
Digital Kitchen Scale
Stainless Steel Mixing Bowl (Large)9
9
Plungers that stick, cream over the top
Plungers that stick, cream over the top
Twin-plunger air-chamber churn troubleshooting.
Flow
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History and honest limits
History and honest limits
**John Andrews** of Middlesex County, Massachusetts, received US 7,298, dated 23 April 1850. He wrote that the streams "so intermingle air with the lacteal matter as to very quickly oxygenate and cause a separation"; that is his account. He claimed the combination of the external chambers, their plungers and passages with the middle or air chamber, and the air-entering passages d.
**Honest limits.** A food-safe box and printed parts stand in for his wooden box and plungers. FDM prints hold food in their layer lines, so wash well and replace when worn. Your times and weights are the result.
Materials
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Tools Required
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Design Files
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CC0 Public Domain
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