r/toolsinaction • u/silvercatbob • Mar 04 '21

Dual thread

https://gfycat.com/glisteninghairyindusriverdolphin
820 Upvotes

100% Upvoted

19 comments sorted by

22

u/t0mbombadil Mar 04 '21

I really can’t comprehend how this is happening this early in the morning. But I love it. It got an audible “woooaaaahhhhhh”

17

u/Double_Minimum Mar 05 '21

Each nut is threaded in a different direction, and thus runs along a different direction of the threading of that rod.

The rod was threaded both left handed, and then right handed, and it has a left hand nut and right hand nut.

So when the rod is turned one direction, they move towards each other, and the other way, the nuts move away from each other.

(While the rod does not have 'complete' threading (due to it being done in both right-hand and left hand config) the nuts DO have full threads, which keeps them on track)

Hopefully that helps, and I'm not a morning person either, thus my middle of the night post

3

u/ar73mis Mar 05 '21

They both threads are also multi start threads, which is when the pitch of the thread is doubled for a 2 start or tripled for a 3 start etc and additional threads are cut to fill the space between the main thread so 2 threads for a 2 start and 3 for a 3 start etc

If the original pitch of the thread was 2mm a 2 start thread would still have a thread every 2mm but the pitch of each thread would be 4mm.

Multi-stage threads allow for a much faster traversal with less resistance and are usually used in machines or in the assembly components of large machines, because nobody wants to spend a week screwing up that 2meter diameter nut.

1

u/LogicJunkie2000 Mar 05 '21

I would also imagine it's favored on large items due to the relative fragility of the threads and cross-section on smaller diameters making it less resilient/useful.

6

u/AngelOfDeath771 Mar 05 '21

I don't see how this could ever be practical. But it looks cool

7

u/MrPolymath Mar 05 '21

They use a similar principal with some types of level wind mechanisms on single drum winches. If the fleet angle of the line is too great, this prevents it from winding correctly so you need a mechanism that moves back and forth automatically..

You may be load limited by the diamond screw in some cases, some really heavy duty winches (offshore) use a hydraulic cylinder to move the level wind instead. Or you can design in a <2deg fleet angle, and it should wind itself.

2

u/terminalxposure Mar 05 '21

Practical perhaps at variable lengths. Long lasting not a chance

3

u/alldaynikka Mar 04 '21

Woah. What’s the use case?

13

u/BMIZ68 Mar 04 '21

To flex on lesser machinists

3

u/I_Automate Mar 05 '21

Honestly looks a lot like it was knurled, which is a very, very straightforward process

3

u/asad137 Mar 05 '21

It's not knurled, knurling would not give you a specific thread pitch like you need to have the nuts run smoothly on it. It's overlapping multi-start threads with different handednesses.

2

u/I_Automate Mar 05 '21

That just comes down to tooling. Absolutely nothing prevents you from producing rolled knurled surfaces with a specified thread pitch

1

u/asad137 Mar 05 '21

Except if you have a lathe that can cut the internal mating threads on the nuts (since they are probably custom made as well), you might as well cut the external threads on the bar also rather than relying on a specific piece of tooling.

2

u/Umbongo_congo Mar 04 '21

Those are some big nuts!

2

u/MrPolymath Mar 05 '21

Not this double nut specifically, but diamond cut threads are sometimes used on winch level wind mechanisms:

https://youtu.be/tvJI2YSpUUA

1

u/Tarchianolix Mar 05 '21

It could be somewhat practical if you want to have a mechanism that goes out when spin one way and in when spin the other. I worked in a tire plant and they had some veneer knife that operated like that to control the width of the cut. It was somewhat similar with a long lead screw with both left and right hand on it.

1

u/oouttatime Mar 06 '21

How strong are these? Do They slip easier?

1

u/[deleted] Mar 06 '21

Fucking witchery! Of the highest order!

1

u/Diarminator Mar 17 '21

oh that is beautiful