How many threads per inch on an Imperial micrometer thimble? Don't cheat, figure it out in your head.

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Top responses include:

• “A question on my high school class I taught. Most got it”
• “25 years ago this was actually a question an employer asked me in an interview. He said a machinist should be able to figure this out. Pretty easy when you think about it.”
• “Good question.... that I've asked hundreds of "machinists". Very, very few knew and most of them couldn't figure it out.”

• “I ask this very question when interviewing potential employees. It tells you a lot about them:

  1. They know how a micrometer works (you'd be surprised).

  2. They know about T.P.I. and threads.

  3. If they don't already know, but can figure it out, they have math skills.”

• “1 divided by .025 = 40.” The machinist trade is based off a screw thread! Some of us are not mechanically inclined, but helps to be mathematically inclined.

  Numbers don’t lie!”

• “Well, it moves 25 thou per turn. And there are 1000 thousandths per inch so 1000/25= 40”