Anybody figured out how to make RepRap threaded drive rod?

As part of the effort to make more of the machine from reprap parts, I was wondering if it was possible to do a threaded (studded) rod to use to drive the Z axis on my design. Going from steel to plastic will require a much bigger diameter, say somewhere around 3/4" or 2 cm. I can imagine doing this vertically, but that is usually the shortest dimension of any reprap's work area. Any body have an idea how to do the treads while laying on its side? Or do you build it in stages, with a hole in the middle of the build table to let the already made part stick down?

If we can find a way to make these, it should greatly reduce the amount of steel needed in the axis drive mechanisms.

Mike

Try Rack and Pinion?

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Sebastian,

That is what got me thinking, but I was going in the opposite direction. Instead of putting hearringbone tracks on the structural members and hearingbone gears to walk up and down them, I was thinking of replacing the threaded rod used in Z axes like the Mendel with a larger diameter plastic threaded rod. But, if Forrest can make those gears, then at least the repaps can make a vertical threaded rod. The problem is how to make one tall enough.