Dual-threaded rod - GIF

Dual-threaded rod. Probably not the most practical fastener, and conveniently featured here between both a business and religious advertisement.

<video controls loop>
<source src="https://s3-us-west-1.amazonaws.com/hmt-forum/dual_threaded_rod.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>


Previously:

https://www.homemadetools.net/forum/...984#post149050
https://www.homemadetools.net/forum/...807#post137019
https://www.homemadetools.net/forum/...867#post152552
https://www.homemadetools.net/forum/...161#post141528
https://www.homemadetools.net/forum/...718#post139938

Friggin nice machining!

Quote:

---

Originally Posted by trigger

Friggin nice machining!

---

Not only that did you happen to notice how many thread starts there are on the thing? it looks to be in the neighborhood of 2 to 4 TPI with possibly 16 to 20 starts in either direction

Quote:

---

Originally Posted by Frank S

Not only that did you happen to notice how many thread starts there are on the thing? it looks to be in the neighborhood of 2 to 4 TPI with possibly 16 to 20 starts in either direction

---

It looks like the first nut made a 420* rotation and the second went a 360*, so that's <0.5 TPI? At what point do you stop calling them threads and start calling them splines?

Neil

Quote:

---

Originally Posted by sossol

At what point do you stop calling them threads and start calling them splines?

Neil

---

Or you could call it deep, precision knurling...

Quote:

---

Originally Posted by sossol

It looks like the first nut made a 420* rotation and the second went a 360*, so that's <0.5 TPI? At what point do you stop calling them threads and start calling them splines?

Neil

---

Well they would never become splines as splines are generally parallel to the length. so I guess they would be teeth instead of threads as in the teeth of a worm gear but with as many starts as there are on that thing it is probably safe to say no worm gear would ever have that many teeth. Maybe those of the Gleeson Torsion helical pinion gears might come close. I have seen some right angle drives using gears cut with 10 to 12 teeth in a spiral called spiral helix
SO essentially what the bolt has is a spiral helix thread cut with left and right rotation.
What ever it is the thing is amazing

Quote:

---

Originally Posted by IAMSatisfied

Or you could call it deep, precision knurling...

---

Does look like knurling doesn't it

Makes me want to run down stairs and try it, but I don't have a at least a week to devote to it. Sure would be a test of skills!!!

I am with Frank, 16-20 starts in EACH direction.

Attachment 36150

Quote:

---

Originally Posted by trigger

Friggin nice machining!

---

Look at the bottom end of the threads, I'd bet it was done on a CNC due to the thread tool pull out.
That, or a really fast and skilled machinist.

14:52 video:

https://www.youtube.com/watch?v=cDfMI5ahbJI

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

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

Not a lot of uses, but super cool.

13:25 video:

https://www.youtube.com/watch?v=h8sRZJbIHlY

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...

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.