Has anyone successfully developed a delta 3d printer with arms connected directly on motors (like this http://www.youtube.com/watch?v=Gv5B63HeF1E) or some similar design (different than Rostock design)? I saw several attempts on net that seem to be abandoned, so I’m trying to find a reason for that. From what I saw, possible reason could be that stepper motors don’t have resolution big enough to move long arm with enough precision. Could microstepping, gearing, threaded rod or servo with optical feedback resolve this problem for a modest price?
Two major problems - First is what you described, the precision needed is very very high. Second the stress on the motors and gears is very high as well (resulting in wear, and reduced precision).
And third - with this setup you have very limited Z movement. The beauty of the Rostock is that you can make it as high as you want.
There’s a reason why these things are so expensive