Tightening the left eccentric nuts near the leadscrew leads to this rubbing. Making it any looser will leave 2/3 wheels in a free spin.
I’m starting to think that it would be cheaper to get a P1P…
I think you’ve discovered why cheap Chinese printers are so cheap :) Pretty much all of them have some design flaws, and there’s always a certain amount of gamble with factory assembly and quality control.
This printer only has one z lead screw, right? It can be very difficult to get good contact with all 6 wheels and to completely eliminate gantry sag. If the vertical “legs” of the printer aren’t at the perfect distance it might not even be possible, but sometimes it’s possible to adjust them by loosening the screws, pushing the alu extrusions to one side, and tightening them again. If you’re really unlucky the screw holes aren’t drilled right and you’ll never get good contact. This is an issue for all printers that have single lead screw + v-slot rollers. I spent a lot of time trying to fix this on my Ender before I gave up and bought a kit with a second lead screw.
IMO just try to do it as good as you can, perhaps you can get good contact for all wheels except 1 and then you can ignore that one.
Btw it’s highly recommended that you print some bed cable strain reliefs for this printer, unless Tronxy has added this recently to the model. Otherwise the bed cables can snap
I had similar problems on my sidewinder x1 that had two lead screws, honestly I would recommend skipping the v rollers completely and go straight to something with linear rails or modding some on
Yea I was considering writing a paragraph about how double lead screws also needed some careful adjustments, and wouldn’t eliminate problem automatically, but it felt like the comment was starting to get too long anyway.
Linear rails also needs some work though. If you have two on the Z axis you have to make sure they’re perfectly parallel, and most likely they’ll only have a thin protective oil from factory so you’ll have to clean them and apply a lubricant. Nothing super complicated, but a few steps that are possible to screw up for a beginner :) And when people buy linear rails, many go for the cheapest they find on amazon/aliexpress/wish and those can have manufacturing or quality control issues. If it’s possible to properly align your v-slot rollers, those might actually be better than cheap linear rails. If you pay for quality linear rails that ought to be the best solution. IIRC “good enough” linear rails cost about €25 each, no need to get genuine Mizumi or Hiwin on a cheap bedslinger printer IMO
