MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
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Laszlo, the blind hole is intentional, you just drill it out before assembly. I added in a 1 mm membrane across that hole to allow Skeinforge's bridging code to take care of the overhanging shoulder on the lower bearing mount. Without it, the overhang will sag when printed on a Reprap, but with it, the overhang prints fine.
The idler block gets another skate bearing mounted on a piece of M8 rod. I should add that to the wiki, but you can see it in the photo if you look closely.
Also, OpenScad is great, but I'm not a programmer - I come from an engineering background. Cad tools like Alibre are much faster and easie
r to work with for me, as I spent too many years learning that approach to design. And there's a free version available as well. If you want, I can output a step or iges file that may import better into different packages.