Captive Nut

Nice work man. I have wanted to make one for a while now. I can see frustrating many a friend and my wife with it. ahaha. My 4yr old would figure it out pretty fast I bet.
 
That kind of project is always a dilemma on a forum like this. Do you explain it for the benefit of those who don't already know, or do you protect the secret?
 
I will have to give in!
I will make one myself by making it without the thicker end at one side, weld, weld, weld.... turn it in the end.
Would that be one solution?

Kai


It is a solution for sure, but it defeats the purpose of the puzzle. You need be able to take the nut off and then put it back on again.

"Billy G"
 
It is a solution for sure, but it defeats the purpose of the puzzle. You need be able to take the nut off and then put it back on again.

"Billy G"

I thought the puzzle was in figuring out how it was made. Ideally the bolt heads should have lines and a manufacturer's symbol and the whole thing should have a chromate or black oil finish so that it looks like a bolt straight out of a bin at Fastenal.

Disclaimer: I have neither the equipment nor the skill to do this myself.
 
Thanks to all the compliments on my Captive Nut Project. I didn't really mean to keep it a secret ... for long. I honestly thought most would have already seen something like this. You gotta admit that "thread veneer" was pretty funny. Sometimes I wish they made it!

I found another web site that had another puzzle bolt that I also made. Holding the nut, you can't screw down the bolt head, but you can unscrew it. Holding the nut again, you can screw the bolt head down by turning the threaded end, but you can't unscrew the bolt from the nut

Let's see who can figure this one out. :think1:

IMG_0900.JPG IMG_0901.JPG
 
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If the end of Bolthead piece and the threaded end has a lefthand inclined spiral tip. It might even be a smaller diameter pin/internal thread with a very short thread with a larger pitch than the bolthead and the screw.
The larger pitch of the small pin or inclined spiral would prevent the bolthead piece driving the threaded end, but allow the threaded end to drive the bolthead end towards the nut. The limited length of the Bolthead piece of course prevent the threaded end from beeing unscrewed from the nut.
I see before me some kind of lefthand skewed dog clutch.

Wow: these must be the ugliest English sentences of all time!!!!! English is not my first language. Back to scool again, I would say.

The main thing here is that the Bolthead piece and the Threaded end obviously have the same pitch, while the inteface between them inside the nut has a larger pitch with the opposite direction.

I think!

Kai
 
Let's see who can figure this one out. :think1:

I know how both are done, but haven't tried it yet. That second one is fiendishly simple to do, but I'd never think of how to do it in a million years. The thing that stops me from making the first type is that I really want to do it without having relief at the ends of the threads such as the first picture, but I can't figure out for sure how I would do it without a retracting tool holder. I think I know, but maybe I'm making it harder than it should be. don't want to give anything away here. LOL
 
Mike, a simple way to turn threads like that is to shut off the power on the lathe and turn it by "hand". I've seen a number of different setups where a hand crank has been affixed to the through-hole for this purpose. You might give it some consideration.

-Ron
 
OK, so here is the spoiler for the second mystery bolt project. I didn't take any photos of the captive nut, so you'll have to search the web for pics of that.

Basically, the multiple cuts (51% on both and one turned and cut at 45* as well) create a cam effect that lock the threads in their respective directions and it's all hidden by the long coupler nut. Of course you have to deburr well and carefully adjust the length to get the threads to re-align after cutting it in half. The closer the fit the smoother it works.

Rick

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One Christmas I made a pair of captive nut puzzles for my sons. Below is one completed and the other showing the solution
CAPTIVE NUT SOLUTION.JPG

CAPTIVE NUT SOLUTION.JPG
 
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