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The Apple Parer: A Crank, a Fork and a Knife on a Spring
TheChef

Created by

TheChef

27. September 2026DK
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The Apple Parer: A Crank, a Fork and a Knife on a Spring

Paring a bushel of apples with a knife takes hours. A parer clamped to the table does it with a crank: gearing spins the apple on a fork while a knife on a spring-arm swings across it and takes the peel off in one strip. William M. Griscom of Reading, Pennsylvania, received US 191,138, dated 22 May 1877 (filed 4 April 1877). The machine proper, he wrote, "is precisely the same as those in common use": the turntable parer, whose rotating table swings the knife. His improvement moved the table clamp to the fork end, so "the parings from the latter do not come in contact with said gearing" and the apple is held firmly while it is pushed onto the fork. This rung works out how wide the strip is, how much apple a thick peel wastes and why the knife is on a spring. Then it pares apples by crank and by hand and weighs the difference.
Beginner
About 1 hour

Instructions

1

Strip width, peel thickness and the spring

Loading Jupyter Notebook...
2

The gearing between crank and fork

The crank drives the fork through a gear train that multiplies its speed. The embedded blueprint shows how ratios are chosen.
3

Read US 191,138

"My invention relates to certain improvements in that class of apple-paring machines in which the frame is so arranged that the parings from the apple fall clear of the gearing, as illustrated in the machine for which Letters Patent were granted to my assignees February 22, 1876, No. 173,942". "The machine proper is precisely the same as those in common use" — the turntable type — and "consists of a frame, A, carrying the driving-shaft a, fork-shaft b, and their gearing, and the rotating table B, which carries the spring-arm d and its paring-knife." The clamping-frame D "is not secured to that portion of the frame A adjacent to the operating-shaft a, as usual, but to the opposite end of the frame, adjacent to the fork-shaft b." So "the end of the machine which carries the apple is directly adjacent to the clamp, and is thus held more firmly than usual, all shaking of the apple, or displacement of the machine when putting the apple on the fork, being prevented."
4

The paring cycle

Blockly Workspace

Loading Blockly workspace...

5

Pare by crank, pare by hand, weigh both

Clamp an apple parer to a sturdy table edge. Weigh six apples of about the same size one by one and note each weight. Pare three on the parer and time each from fork to finished. Pare the other three with a vegetable peeler and time them too. Weigh every pared apple and the peel from it. Work out the fraction of each apple that went into the peel, and the average time for each method. Measure a few peel strips with a caliper for width and thickness and compare them with the notebook. Keep the fingers clear of the fork and blade while the crank turns.

Materials for this step:

AppleApple6 pieces

Tools needed:

Apple ParerApple Parer
Vegetable PeelerVegetable Peeler
Digital ScaleDigital Scale
StopwatchStopwatch
Digital Caliper 6-InchDigital Caliper 6-Inch
6

A parer that tears or skips

Apple parer troubleshooting.

Flow

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7

History and honest limits

**William M. Griscom** of Reading, Pennsylvania, filed US 191,138 on 4 April 1877; it is dated 22 May 1877. It improves the machine patented to his assignees on 22 February 1876, No. 173,942, and describes the parer itself as the common turntable type. **Honest limits.** The patent gives no gear ratios, speeds or sizes. The apple radius, turn counts and lumpy shape in the notebook are examples. Your own weighings are the result.

Materials

1
  • 6 pieces
    Placeholder

Tools Required

5

CC0 Public Domain

This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.

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