Captive nut

[mklotz]

Yes, mathematically it is an ellipsograph. The crank handle traces out a perfect ellipse.

 

[Blogwitch]

I've never made one, but one day........

I don't know if there is a mathematical formula for it, but I did used to use two small nails, a length of string and a pencil for marking out rough ellipses onto a piece of paper.

There must be a way of working out the distance between the pins and length of string to give you what you want exactly.


John

 

[Bluechip]

There is a way using a Directrix and a whole lot of convoluted maths ... IIRC ??? Long, long time ago.

Some insight here.

http://mathworld.wolfram.com/Ellipse.html

Otherwise you can use this construction, much easier.

http://www.mathopenref.com/constellipse1.html

OK John ... you prefer the string bit eh ??

Me too ...

BC

 

[Blogwitch]

Ahah! Dave,

Now I understand my bit of string and two nails and how to do it repeatedly.

Thanks

John

 

[basement_guy]

I've never made thread on the lathe. This was a fun way to learn.

The inside thread was made with a tap. All outside thread with the lathe.
M6 inside an M10 outside.

 

[terrywerm]

I found that the links to the puzzles/projects on the Frets.com page were no longer working and found that Mr. Ford has done some changing on his website and the captive nut puzzle is now located here:

http://www.frets.com/HomeShopTech/Projects/CaptiveNut/captivenut.html

The "Two Slider" has also moved and is located here:
http://www.frets.com/HomeShopTech/StepByStep/TwoSlider/twosllider1.html

 

[rleete]

These are great to take to work. Put it out in the open and let people fiddle with them. Make up stories as to how it was made, but never reveal the real secret.

 

[ChooChooMike]

Dang !! Forgot about that little puzzle Had bought materials a few years ago and put them aside and promptly forgot to make one !

 

[basement_guy]

I showed the pic of the captive nut to my colleague. He wondered how i made it.
Tomorrow is his birthday so I made him this little present. It is M6 on the outside and M3 inside.