# Captive nut puzzle...my first "real" lathe project



## Threadkiller (May 31, 2019)

Hey all. Up until this project Ive just tinkered and arbitrarily turned down stock. I wanted to see if I could successfully cut threads and just work on taking measurements and fundamentals. I always wanted to make one of these and thought it would be a cool little piece to have, so I figured Id give it a shot. It came out pretty decent aside from the poor surface finish resulting from a broken insert. I did one side and I didn't have anymore so I had to ruin the other side to match haha. I took it easy on myself and used aluminum but definitely want to make one out of steel in the future. Last night I took some emery cloth and some files to it and cleaned things up a tad but didn't take any pictures. Comments, advice and criticism welcome.


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## tjb (May 31, 2019)

Made one of those myself some time back.  It's a great exercise - makes you think ahead while you're milling it.  Like you, I figured this would be an interesting project to practice thread-cutting.

I like to show it to mechanics, tinkerers, etc.  I don't tell them it's a puzzle.  I just say I can't quite figure out how I got that nut on there, and now I can't figure out how to get it off.  (I made the ends only about 3/16" longer than the threaded section, so it looks 'possible' to remove the nut.)   You should hear some of the theories guys come up with!  Only one guy figured out what I did.  Interestingly, if I lined up everyone I showed it to and guessed who would 'get it', it was him.  And he got it in about 6 seconds.  The guy is a mechanical genius.  He should be a machinist.

Regards,
Terry


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## higgite (May 31, 2019)

Good job, Threadkiller. That was one of my first “real” projects, too. I was amazed at how the seam literally disappeared when you screwed the 2 halves together and machined the threaded part as one piece. I hear some folks Loc-tite the 2 halves together so no one can unscrew them and say, “Aha!”. I didn’t Loc-tite mine. I just screw it together as hard as I can by hand. I figure if someone solves it, they’re entitled to their “Aha!” moment.

Tom


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## Threadkiller (May 31, 2019)

tjb said:


> Made one of those myself some time back.  It's a great exercise - makes you think ahead while you're milling it.  Like you, I figured this would be an interesting project to practice thread-cutting.
> 
> I like to show it to mechanics, tinkerers, etc.  I don't tell them it's a puzzle.  I just say I can't quite figure out how I got that nut on there, and now I can't figure out how to get it off.  (I made the ends only about 3/16" longer than the threaded section, so it looks 'possible' to remove the nut.)   You should hear some of the theories guys come up with!  Only one guy figured out what I did.  Interestingly, if I lined up everyone I showed it to and guessed who would 'get it', it was him.  And he got it in about 6 seconds.  The guy is a mechanical genius.  He should be a machinist.
> 
> ...



Hey Terry thanks for the response. It was a lot of fun figuring out the order of operations needed. I may leave the ends shorter next time. That's a good idea. One guy I showed it to asked me if I pressed the nut on ha.



higgite said:


> Good job, Threadkiller. That was one of my first “real” projects, too. I was amazed at how the seam literally disappeared when you screwed the 2 halves together and machined the threaded part as one piece. I hear some folks Loc-tite the 2 halves together so no one can unscrew them and say, “Aha!”. I didn’t Loc-tite mine. I just screw it together as hard as I can by hand. I figure if someone solves it, they’re entitled to their “Aha!” moment.
> 
> Tom



Thanks Tom. Yeah I was surprised too how the seam disappeared. I loctited the two halves together haha I cant have anyone knowing my secrets!


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