Dual-threaded rod - GIF

[trigger]

Humble genius,I would have freaked if they shut my power down at third run,amazed at the smooth function .Nastarovia Comrade

[TheElderBrother]

I'd love a large bolt like this to use as a knife handle. Super cool.

Not a lot of uses, but super cool.

[Jon]

13:25 video:

[TheElderBrother]

Blows my mind. But would a setup like this be especially effective as a fastener? The nut probably couldn't get any purchase on the bolt...

[hemmjo]

I doubt the intention was to fasten any parts together.

However it clearly has enough strength to "fasten" our attention to the whole process, the skills and imagination of the machinist.