They shouldn't be able to screw this way

This image doesn't explain anything.

"Two nuts are moving in opposite direction although they are rotating the same way. The bolt has a continuous thread. This is from a Swedish TV show."

Magic nuts and screw threads


  1. The video caption says, "The bolt has a continuous thread." Is that asserting the bolt has conventional threads, or is it just a weaselly way to trick the reader into thinking "continuous" means it's a "conventional" thread?

    For what it's worth, the video inspired me to build a bolt and nuts that behave similarly. Mine uses an unconventional thread, but it looks like an ordinary thread and it's technically "continuous." My first prototype is pictured at:

  2. Scott:

    Very cool that you were able to build it. I don't know how the original works, but you might be right about "continuous" suggesting "conventional" but not actually meaning "just like a real bolt." Those deceptive, weaselly words are everywhere...

  3. It'll interest you that I made a second version of my own Wrong-Way Nut that behaves more like the one in the Magic Nuts video. Assuming it's an honest demonstration (and I promise it is) I think I've improved upon their video:

    * I thread the nuts onto the bolt one-at-a-time.

    * You can see the threads advance when the bolt is turned, which confirms it's a continuous thread not a series of ridges.

    * Because the bolt is turned during the video, all sides of the threads are shown.

    * I spun the nuts and let them pull themselves along the threads, which means one isn't just being slid along the rod by sleight-of-hand.

    * Both nuts are eventually shown to travel the whole length of the threads.

    I don't have inside knowledge into how the "Magic Nuts and Screw Threads" video above was done, but I'm convinced it was probably honest now that I've built my own model and made my own video:

    This was a pleasant, satisfying experiment. Thanks for the inspiration, and the excuse to tinker!


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