This ain’t pretty, but darn clever.
http://www.instructables.com/id/MilkRap-Milk-Crate-RepRap/
I like the idea of simply using thicker Z screws (which will more likely be straight, and easy to source locally) for linear motion. Gets rid of a nice chunk of smooth rod that you need to buy.
@ThantiK I’m sure it’s possible to get screws that are that straight, but how likely it is I do not know. It will be interesting to see some prints.
@Ben_Malcheski , they’re rolled, so out of the factory they’re pretty darn straight I imagine. I think it’s the thickness that determines how much deformation they get through mishandling, etc.
Ah. Here I can give some direct experience. Straight ball screws are easy. What isn’t so easy is getting them rotating perfectly without any run out. Even 1/8mm is very noticeable in prints as its so regular. You need really strong end bearing mounts with no slop what soever and a very well aligned coupling to the motor. Ball screws are also a shit to maintain. I have one in bits i just gave up trying to get back together. In short, its doable, I got the alignment good enough to produce a good print but not without weeks and weeks of fucking tinkering and any play/shift would kick out the alignment and I’d be back to tweeking again. My G+ photos show my mendelmax with this setup but I eventually went back to shafts and lead screws.
@Tim_Rastall I could see ballscrews being a pain in the ass here, but there are bearings which typically are made to the tolerances for this kind of thing. At the bottom you could add 2 counter-tightened nyloc nuts against a proper bearing and I’d figure that would prevent runout. Can’t really do that kind of thing with ballscrew. Add this to another bunch of stuff I’ve gotta try…