Metal lathes are capable machines that played a large role in the industrial revolution, and an incredible tool to have at your disposal. But that doesn’t mean they can’t be used to have a little fun, as demonstrated by [Oleg Pevtsov] who made a bidirectional bolt as a machining exercise just because he could.

Both videos after the break are in Russian, but the video and auto generated subtitles are enough to get the main points across. The bolt is an M42 size with a 40 mm pitch, with grooves cut in both directions to allow left-handed and right-handed nuts to be threaded. The large pitch means that instead of a single continuous groove like a normal bolt, ten separate grooves need to be cut for each threading direction to cover the bolt surface. Since this was all machined on a manual lathe, a dial indicator was required to maintain accurate spacing. It took [Oleg] four painstaking attempts to get it right, but the end result looks very good. Instead of a fixed cutter, he used a trimming router mounted on a custom clamp.

[Oleg] also machined three different brass nuts to go on the bolt with a fixed cutter. First left-hand and right hand threaded nuts were made, followed by a bidirectional nut. Due to the large pitch and careful machining, all three nuts will spin down the bolt under the force of gravity alone. Although the bidirectional nut doesn’t move as smoothly as the other two, it can change rotation and translation direction at random.

While this is a one-of-a-kind fidget toy, have any of our readers seen a bidirectional bolt or lead screw in the wild? We can imagine that the ability to move two nuts in opposite directions on a single lead screw might have some practical applications.

It’s possible to make incredible parts on a manual lathe. A handbuilt V10 engine and a pneumatic hexacopter model are just two examples of what’s possible with enough skill, knowledge, and patience. Sadly it is a fading form of craftsmanship, rendered mostly obsolete outside of hobby projects by CNC machines.

I must applaud the lathe work, amazing control. Many Russians seem to have this sort of mad genius spirit. I remember contemplating a bolt threaded in both directions as a child, I didn’t have the equipment to cut one at that age, people said it was a stupid idea and I didn’t take it any further. I’m glad I’ve learned to stopped listening to people like that these days. I still think this needs a left and a right handed bolt to be a full set, but still amazing work. That’s a pretty hefty chunk of metal, especially for a, because I can, project.

I still think it’s not that useful. That thread is much weaker, needs VERY precise machining for smaller sizes (which means it will be expensive) and double threaded nut will tighten or loosen in the least desired direction when rotated any way. The only upside is that you can tighten those nuts using only one wrench. Classical solution looking for a problem.

As for machining – very neat and ingenious use of a lathe.

It is not useful at all. That is not why it was done. Without people like that Hackaday would not be worth the electrons it takes to run it.

This is a piece of art that is beautiful and functional .

/offtopic/ Great you stopped listening to those people. Everyone should be encouraged to try and make their ideas a reality, especially the younger ones!.

It seems to be a mark of every good idea that people will say it is stupid. Sometimes they are right of course, but more often than not it means you are onto something when people say that.

Reality begs to differ. People tend to say it’s stupid because most ideas ARE stupid, so of course when they come across a good idea the initial reaction will be the same.

“But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.”

That would make for an awesome ratchet mechanism worth patenting, exit the annoying loosening of mechanical clicket cog… just put a left nut and a right nut with corrugated surfaces face to face on the rod, and solder a “Y” handle, you then have a one direction axe rotator with maximum torque transfer and minimum wear and tear…

I wonder if you could somehow omit some of the cuts to make a pair of nut and bolt that can be screwed on in either direction, but that will “remember” the way it was initially screwed on until you fully unscrew it again.

Of course, that would not look as pretty.

Yes, one could make such a nut. It would though need its threads to have a pivot at their start that the rest of the thread then follows after.

Though, how useful that is in practice is a different story.

One could also make the thread into many smaller sections that are able to rotate. Driven by an internal cam that is controlled by a leaver at the thread start. The thread start itself would though have to be able to travel in any direction, but if meet with a thread going in one direction, it will push a leaver and push over the cam and thereby the thread, ensuring that the nut can only be threaded on in that direction. The leaver for the other thread direction will mostly sit forgotten in the space not used by the current thread. And of course such a nut would need a spring return.

A nut of this complexity would though make a lot of people shiver, though, maybe a challenge for a watch maker or camera lens manufacturer to tackle?

A device that is a bit simpler, but yet having many parts would be a gear with pivoted teeth and ball bearing faces, this would theoretically having amazingly low friction and thereby losses, but will be fairly abhorrent in practical applications where torque is remotely needed, due to all the small parts making up its structure, unless one has plenty of space to build it.

Reminds me of the piston inside a piston design of manual coffee makers (valve and piston as one assembly). When the piston is pushed the inner piston sits flush against the bottom of the outer piston and the chamber is pressurized, when the piston is raised, the inner piston raises within the outer piston to allow fluid to be drawn around the inner piston and through the outer piston filling the chamber again.

Or, more simply: just cut different thread pitches in the left and right hand directions

Yes, there is far simpler methods of making a nut able to thread in both directions, but only in one direction at a time.

Can use a 12 start pattern, but just skip in certain patterns. For an example using the start pattern: 1, 3, 5, 7, 9, 11 for one direction and 1, 2, 5, 6, 9, 10 for the other. They won’t engage with each other and provide the same strength in both directions, and likely an interesting pattern as well.

Trying to wrap my head around this is hurting my brain XD

It’s basically a lock and key system. A pattern in one direction uses even threads, a pattern in the other direction uses odd threads. Some starts are mutual, so the same nut fits either pattern.

The resulting thread on the rod won’t have the 4th, 6th and 12th thread. So that will likely end up with an interesting swirly pattern down the rod. Almost feel like making such a thread myself…

First shop I worked in, my boss, who is likely dead by now, as he was old, told me of a secret thread on the very first night vision scopes, which he was instrumental in machining, for Desert Storm.

He told me how he created a thread on a standard lathe that was neither imperial or metric, but based somehow off of a sinewave equation or something, by adding in a secondary input train between a set of gears so that the output thread was something that could never be duplicated except by him.

At one point he explained to me how it worked, but I still puzzle to this day how he actually did it. He explained to me that on critical items, that were protected trade secrets, the print would often intentionally be drawn wrong with impossible callouts, and only the creator could reference the details enough to decode what was actually intended.

I assume at this point, the secret is lost, the shop has been bricked over and condemned, perhaps prints of this locked in a safe somewhere, or even burned.

I’ve always wanted to try to recreate a thread like this, something impossible to duplicate. It was somehow derived from a mechanical mathematical function for a sine wave, if I remember the explanation.

Can anyone describe how such a thing would work? It’s one of the oldest mysteries from my career. I believe he told me so someone would know that things like this were possible, but he was certain that noone could ever physically duplicate it, so he told me.

It might just be that he set up the lathe to cut a thread that wasn’t on the tables. There are lots of gear combinations that will cut a perfectly good thread that does not conform to any standard. But nowadays, with a CNC lathe, you can just type in any pitch you want and it just happens. There isn’t really much to go on, so he might have done something slightly more interesting than that.

All of these are very interesting ideas. Now I am not as versed in Machining (I have some mentors who are though; I’m an electrician myself). What about simply making the bidirectional nuts as locknuts? The nylon would hold it in place.

Now obviously, this is more a beautiful piece of art and a strong demonstration of skill piece, which stands in its own right. However, I feel like if this were a practical piece in theory, you’d want one piece fixed and one bidirectional, right? Typically left hand thread and such are used on rotational equipment to my knowledge to prevent loosening, correct?

what does a machine thread have to do with night vision anyway — sounds nonsense to me as a system of optics and light transmission or enhancement is not mechanical!

WOW ! Beautiful machining ! More of a work of art. Ummm but this the potential to cause a halt to mankind’s mechanical progress……lefty tighty ???? righty loosy ???? righty lefty tighty loosy ????

Not _exactly_ the same, but the “Yankee” pattern screwdrivers had a bidirectional track. https://en.wikipedia.org/wiki/Yankee_screwdriver Disappointingly two of those in the accompanying photo are shown retracted so the screw can not be seen.

I found out about these because of a throwaway scene in the movie The Blues Brothers, where Jake has one in his inner jacket pocket, that he pulls out to disassemble a speaker grille. Some day I’ll find one in a junk/pawn shop and it’ll be mine.

Hey, are you on .io? I wanna chat with you but theres never been a way to reach you.

First thing it reminded me of too. I had a conversation with myself about where the hell I put mine (2?) and why come I don’t use it. I concluded it was because the bits were a bit chewed, it was hiding away with the more cabinet type woodworking tools that haven’t seen much light, and that it never dawned on me 15 years ago that 1/4″ hex drive was here to stay and it wasn’t just the latest fad, so that’s why the hell I didn’t make an adapter.

I think I’ve got 2, a Stanley one similar to wiki photo and a bigger rounder ended Sears one. Possibly a third is still following me round in the bottom of a neglected box that was a cheap chinese clone I bought when I was probably 15 (Actually didn’t work too bad) but that one was last sighted twice as long ago as the others.

“While this is a one-of-a-kind fidget toy, have any of our readers seen a bidirectional bolt or lead screw in the wild?”

Yes- While the pitch makes it more of a helix or spiral than a “thread,” a follower linked to a shaft with a bidiectional spiral forms the basis of the mechanism (in my fishing reel) responsible for making sure that line is laid down in even layers.

3D-Print your own: https://www.thingiverse.com/thing:4690959

Topping it with a reverse thread: https://github.com/DrLex0/print3d-reversing-thread-bolt

Can’t you just look in a mirror while they cut the threads?

Time to add another entry to https://i.imgur.com/Y89x3aJ.png

I suspect…. if you were to drill a pair if holes, each hole intersecting one thread run, Either clockwise or counterclockwise, A pair of pins, with their tips ground to match the threading, could be used to selectively block one course or the other, Creating the ability to select directionality

You mean… a bolt with a railroad switch? :D

Or have different pitch for clockwise and anti-clockwise threads.

They use these in industrial winches to layer the cable

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fneilarmstrong.whoi.edu%2Fwp-content%2Fuploads%2Fsites%2F47%2F2015%2F11%2FN807870.jpg&f=1&nofb=1

they are called Diamond Screws, and they automatically change direction when they get to the end of the travel.

Self leveling fishing reels for the last 100 years. Except the thread is followed by a wire or rod instead of a nut. The nut here is impressive.

Like the level wind mechanism on an open fishing reel.

You can find that same shaft in old dot matrix (IBM cash register) and even older Selectric ball printers (NCR 270 Bank Terminals) The motor only had to spin the shaft one direction where a sleeve under the print carriage would auto reverse at end of travel.

lol, I say the same about Imperial :) Trying to find metric gas fittings down here in New Zealand where we mostly use Metric is like seatching for hens teeth. And because Metric is what we use purchasing an Imperial Tap and Die costs you sometimes more than twice as much as Metric.

That’s because there aren’t any metric gas fittings. [1] There is the American NTP: https://en.wikipedia.org/wiki/National_pipe_thread And there is British BSP: https://en.wikipedia.org/wiki/British_Standard_Pipe which is the ISO-7 standard, defined in mm but designed in inches. [1] This isn’t entirely true, miniature pneumatics often uses M5 and M3 threads as the ISO-7 threads only go down to G1/16.

For a project like this one, the choice of units is only a calibrated way of saying ‘some’. The choice only acquires value if you need the part to fit something made by someone else in another shop.

SI units have distinct advantages when you have to convert from one physical property to another, which is why they’re nearly universal in fields where you have to do those conversions. For simple quantification, there’s no meaningful advantage one way or the other.

40mm pitch! wow! that alone makes for one odd looking nut!

Sounds like the ‘Tute Screw. Either way you turn it, it only goes in.

https://archives.rpi.edu/blog/2008/03/04/the-tute-screw

Great for pranking car shops. Have both bolts on rotor and the nuts for tires cut bidirectional. That way when someone uses impact tool to loosen them, it’d suddenly tighten instead of coming off.

I figure it would just strip it like a cartoon character eating corn on the cob.

Fine skills.really impressive. Kudos

One way he could improve on it is: Have different spacing for clockwise and anti-clockwise threads. Say, for example, right-hand groove on screw could have a 40mm pitch and left-hand grove on the same screw could have 55mm pitch. This way, bolt tightened clockwise can only be loosened anti-clock wise, and vice-versa.

John n That would not work as you would only have to undo or tighten alittle more and the threads would match again

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