He did told me on twitter that he was intentionally controversial to start the debate which is important for open source community. Without discussion there is no progress and that is the point that some of his commentators do not understand. They just went into attack mode "HOW DARE YOU TALK ABOUT PROBLEMS!!!!!.
Problems he describes:
- Hanging Z-axis
- Two Z-axis motors
- Lots of wire strain
- Hard to maintain - easy to mess up
- X axis wobble
I don't't have lot of experience with Prusa Mendel, but I read or heard about most of those problems, but never tough of them as design issues. I just never connected the dots.
Many of those problems can be solved with upgrades and later Prusa Mendel designs made improvements to address those issues. And there is the Prusa I3 :-)
Josef Prusa responded to this video:
first, my name is pronounced "proosha".
As you said, its old model, no reason to bitch about it in 2013 you are three years too late ;-)
It is still built as there are thousands of ppl who can help you with it.
Hanging Z axis was made because it transfers less wobble to the print, now with tube couplings, its not needed. Your coupling slid out of the shafts either because they were oversized or you didnt tighten them. Sanding the motor shafts helps a lot too. Your cables broke as you didn't bolt them to the Y carriage or used poor cables. Two motor Z axis is much easier to maintain then the original mendel one, if you would built original mendel, you would know. That thing sucked to calibrate. The x axis wobble is true, but during prints it wasn't affecting the quality too much. ...
Anyway, keep up the good work.
Let's talk abut problems. Criticism is free consulting.
Here are videos by Allen Jetter that describe how he improved his Prusa Mendel and changes / upgrades he made. He invested lot of work and time. It doesn't solve all problems mentioned above and raises some new issues, but it is good illustration on hove to move ahead.