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.
As per request, Here's a video of it:
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.
Uploaded the quad helical nut/thread. This should help with any wear issues, as well as addressing any concerns with backlash.
Print some threads,
print a nut
The center of the threaded rod is hollow, connect multiple pieces using a 5mm rod.
The nut might be a little tight at first. Once you work it on the threaded rod, the interior edges become very smooth.