This is not a mill. There are no forces involved, no end mill spirals pushing or pulling. The z axis screw is heavily loaded to one side...there is no significant backlash. Not even on the V2 with the brass nut (which has no specific anti backlash features). There is also no difference in print quality to the other printer versions with ball screw (we have both versions here). The ball screw versions have the nut base slightly loose on purpose to avoid any binding or wobble. This may make the system a bit more sensitive if you intentionally bump the printer, but it will never experience forces like that due to the actual print process. So the fact that you saw a minimal z axis shift when you bump the printer does not mean that the whole system is a bad design. There could be other reasons, too...the build plate could not have been seated fully and the bump seated it, etc.
The final proof is the fact that the surfaces are not looking any different since introduction of the z lift feature. Earlier software versions did not move the z down and back up during rapids and the surfaces did not look any smoother (more like the opposite…the nozzle would slightly scrape over them). IMHO the z axis repeatability could not be any better and this is also an essential contributor to the outstanding wall quality of the prints.
What kind of better materials did you recommend them? What is better for a virtually force free axis than an already complete overkill Japanese ball screw?
Wow Andre! you are right!
1. This has all the movements of a mill.
2. The forces are lighter in some aspects but still there and influencing the system.
3. The Z-axis screw is loaded to some extent but the observation I have seen directly and on this forum from others shows signs on every flat surfaced part with obstructing features a "Z" miss alignment (striping).
4. All versions of this type of ball screw Z axis will have this issue in some manner as there is no direct measured feedback to the controller such as a linear encoder to express the position.
5. As to bumping the system, OK lets remove an external force that could cause this, are there any internal components that might contribute to shifting the system, I wonder? (do I need to mention the extruder components mass?)
6. As to you assuming my opinion of the Zortrax as a "bad design" from my comment "due to a mechanical design error" shows a trollish nature and I do not feed trolls.
7. A good observation about the "build plate could not have been seated fully" but not consistent with the fact of all the other pictures and posts from others including my observations directly.
8. A final proof? the surfaces look the same (inconsistent) as they did before....... you understand that means the issue (if we consider it one) was not solved, only reduced in value.
9. The outstanding wall quality, yes they look great on the Zortrax and my experience with printers that move the build plate in one axis (Z) and those that move in two (Z and X) that could be (in my humble opinion) due to the repeatability of that extra movement of the large mass of the build plate.
10. I feel no more need to again pass along my knowledge and hard work on this subject as I expressed it to the correct parties already and there would be no return on another investment.
11. The assumption without measurement of a "virtually force free" mechanical system sounds like someone wants to sell me a "perpetual motion design".
Lastly, what do you have against "Japanese ball screw"
OK OK that may have been a little too much, so lets just say that we do not agree on much.