"Impossible" screw - video

[Jon]

"Impossible" screw. Bonus points for using a carrot to demonstrate how the trick works!

4:26 video:

Previously:

MagRevolver magazine screw holder Kickstarter - photos
Correct way to drive a screw - GIF
1871 automatic screw-making machine - video and photo

[hegefer]

Wow! Brilliant!

[CharlesWaugh]

I just made one with an angle grinder and a file.
Works great!
I can't wait to amaze my friends and confound my enemies tomorrow. (except... I don't have any enemies to confound)

[Bony]

Mmm I must be trying too hard, had 3 attempts very carefully using exact specs, collets and rotary table on a milling machine. It wants to work, but doesn't quite. Maybe I should just use an angle grinder and file.

One more try before I give up.

[CharlesWaugh]

Confession:
MIne worked great about ten times with a couple of different people (quite confounding for them and deeply gratifying for me!)

Then, it crapped out!

It would lock up on one end but not the other.

Red face, grumpy show-off, etc. ensued.

:-)

[Bony]

Same here, I think the locking works fine for a few times then the threads wear enough for them to engage again, which is exactly what I found. Annoying as I haven't had the gratitude yet.

Did you use M5 thread? I tried M10×1.25 then M5×0.8 twice, with the same result. Maybe a courser pitch may prevent engagement for longer. I silver soldered some knurled brass knobs on each end of the threaded rod so that the join between them was unable to be seen even if the nut was screwed to either end.

Looked great but simply allowed more force to be applied to the threads so they locked even fewer times before engaging again. Grrrrrr.

Tony

[ranald]

Same here, I think the locking works fine for a few times then the threads wear enough for them to engage again, which is exactly what I found. Annoying as I haven't had the gratitude yet.

Did you use M5 thread? I tried M10×1.25 then M5×0.8 twice, with the same result. Maybe a courser pitch may prevent engagement for longer. I silver soldered some knurled brass knobs on each end of the threaded rod so that the join between them was unable to be seen even if the nut was screwed to either end.

Looked great but simply allowed more force to be applied to the threads so they locked even fewer times before engaging again. Grrrrrr.

Tony

OK . It was a turn ip for the carrot. I must try when back home.

[aphilipmarcou]

Very cunning..... I am trying to think of a practical use (on some machine etc) other than confusing friends....

[that_other_guy]

They're kinda spendy, but Lee Valley tools sells one in one of these sets:
Trick Bolts - Lee Valley Tools