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Self-Righting Jumping Hurdle: Off-Centre Pivoted Swing Between Two Standards (Boy Mechanic, 1915)
C. C. Fraser's hurdle from The Boy Mechanic, Book 2 (1915): a 36 by 18 in swing hung on long nails slightly off centre between two standards joined by a reach. It turns at the slightest touch of the jumper's foot and rights itself again.
Beginner
About 2 hours
Instructions
1
1
His cutting list in centimetres
His cutting list in centimetres
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2
2
Read The Boy Mechanic, Book 2
Read The Boy Mechanic, Book 2
"The hurdle consists of two standards, a reach, and a swing."
3
3
Make the swing
Make the swing
Nail four pieces about 7/8 in thick and 1-1/2 in wide into a rectangle: two 36 in long and two 18 in long.
Materials for this step:
Pine Board1 piece
Nails1 pieceTools needed:
Hand Saw
Hammer
Tape Measure
Pencil4
4
Make the standards and reach
Make the standards and reach
Make each standard of three pieces 7/8 in thick, 3 in wide and 18 in long, nailed firmly together as in his figure, and join their bases with a reach of the same stuff, 36 in long.
Materials for this step:
Pine Board1 pieceNails1 pieceTools needed:
Hand SawHammerTape Measure5
5
Hang the swing
Hang the swing
Bore a hole in each standard large enough for a long nail to turn freely but too small for its head to pass, and hang the swing on the nails at its ends, slightly off centre, so it swings at a touch and rights itself.
Materials for this step:
Nails1 pieceTools needed:
Hand DrillHammer6
6
Troubleshooting
Troubleshooting
Hurdle troubleshooting.
Flow
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7
7
History and honest limits
History and honest limits
From "How to Make a Hurdle" by C. C. Fraser, in **The Boy Mechanic, Book 2**, Popular Mechanics, 1915 (Project Gutenberg 44585; checked on the archive.org scan boymechanicbook200chic2, p. 145). How far off centre the pivots go is not given. The tools and metric figures are ours.
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