This is a small 200m test print of some threaded rod I made along with a matching nut. It is a double helix with 1 turn per 50mm. The math works out like this:
For a standard 200 step/ rev stepper motor
50mm / 200 step = .25mm per step
add in a 2:1 gearing or half step motor controller and you have .125 mm/step
add both and it's .0625 mm/step
From what i can tell, there is no perceptible backlash and the nut slides very freely.
I'm sure I'm going to incorporate this into my shuttle system or a printer somehow.
Enjoy...
Edit:
As per request, Here's a video of it:
http://www.youtube.com/watch?v=Hkjf8x__SrE
The video shows that it's loose enough to slip down on it's own.
I would recommend printing one to test tolerances for yourself.
Edit 6/18/2011
Uploaded the quad helical nut/thread. This should help with any wear issues, as well as addressing any concerns with backlash.
| nut.stl | 241.7KB | |
| quadhelical.stl | 2.9MB | |
| quadnut.stl | 458.4KB | |
| testthread2.stl | 1.8MB | |
| threadNnut.scad | 873.0B |
