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Question

Difficulty: EasyScrews and Threads

A lead screw on a lathe has 8 threads per inch (TPI). How far, in inches, will the carriage move if the screw is turned exactly 12 full revolutions?

Answer: 1.5 inches

Answer

1.5
Because the screw has 8 threads per inch, completing one full revolution advances the screw exactly 1/8 of an inch (0.125 inches). Turning the screw 12 times results in a total linear movement of 12 * 0.125 = 1.5 inches.

Step-by-Step Solution

1
Determine the pitch of the screw.
Pitch = 1 / 8 = 0.125 inches per revolution.
Pitch is the linear distance a screw travels in one complete revolution, which is the inverse of the TPI (Threads Per Inch).
2
Calculate the total linear distance traveled.
Distance = 0.125 inches/revolution * 12 revolutions = 1.5 inches.
Total distance is the product of the distance per revolution and the number of full revolutions.

Key Concept

The relationship between Threads Per Inch (TPI), pitch, and linear travel distance of a screw mechanism.

Alternative Method

Set up a proportion based on the definition of TPI: If 8 revolutions move the carriage 1 inch (since there are 8 threads in one inch), then 12 revolutions will move it 12 / 8 = 1.5 inches.
Estimated Time:45s
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Topics

Screws and Threads

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