I had previously posted about some horizontal line issues I’ve been having, and I tried a lot of the suggestions I got; Unfortunately the issue persists.

I saw a video today, where someone mentioned that these connections that are basically responsible for raising and lowering the printer head should be somewhat loose, and not tight (as I had them).

Does anyone know if this is true? The video creator said that it is to allow for some ‘forgiveness’ between the two screws that drive the printer head up and down.

  • @[email protected]English
    1•11 months ago

    Hey OP, Z threaded rods are never 100% stright (like smooth rods should be) and making these nuts loose can help against binding, so yeah it is true, but check few things before you do that:

    1. Clean threaded rods and relube with grease, also clean your smooth rods and relube with sewing oil (should be done once a month or 2)
    2. Have you added bearings on top of the treaded rods? Lot of people do that and its wrong! (Top corners are cropped out of the photo) It can overconstrain Z axis and cause binding, so remove bearings if you added them, top side of threaded rods should be free
    3. Remove threaded rods and roll them over flat surface like glass. Its easy to tell if they are bent and if they are try to strighten them a bit. Also inspect rods and nuts for any damage. Edit: your threaded rods are part of motor assembly so this step might be more difficult
    4. Remove threaded rods (or nuts) and move X gantry up and down with your hands and make sure everything is moving smoothly and also make sure nut position is aligned with Z motor axis. If its not aligned you should adjust frame (loose screws, make everything perpendicular/parallel and thighten again). Z motor axis must be parallel to smooth rods and both should be parallel to each other (check motor brackets, try loosing motor screws and align it better)

    If threaded rod is bent you can loose threaded nut to avoid binding, but it would be better to replace the rod (or motor). Some level of bent rod is acceptable, but too much will cause issues like this

    How long do you own this printer? Have you got it used or new? Was it printing fine before?

    • @rootOPEnglish
      1•11 months ago

      Thanks so much for all the pointers! 1, 3, 4 I will give them a try. I’ll have to see how to disconnect the threaded rod from the motor so that I can roll it on a surface (I’ve done similar with arrows in the past).

      For 2, the top is open, nothing was modified. This printer was bought used years ago (maybe 4-5 years ago) and used to print perfectly. It was not used for the last 3 or so, and has gone through several moves. When we unboxed it again, there were a few broken parts that we had to reprint (the upper stabilizers that go around the support rod and threaded rod, and the y axis motor mount in the back). So it’s not inconceivable to think one or both of the rods could have been bent as well.

      • @[email protected]English
        1•11 months ago

        No problem, hope you find the cuse. Oh broken parts…I would inspect all mechanics and obviously clean and relube

        I dont think you can remove threaded rod from your motor, but im not 100%. There are motors with motor coupler connecting to threaded rod (which can be simmilar issue if you dont leave a tiny gap between motor shaft and rod).

        • @rootOPEnglish
          1•11 months ago

          Thanks, I’ll give it some proper TLC soon and clean/ lube everything.

  • @[email protected]English
    1•11 months ago

    I cannot see images (“these”), but if you are talking about some wheels, yes they should not be too tight neither too loose. Once tightened you should be able to turn them with your fingers without raising gantry but you should also feel friction.

    • @rootOPEnglish
      1•11 months ago

      Ah, it’s the part that the screws actually use to move the head up and down to which I was referring. It’s a couple black circles on the Prusa MK2.

  • @j4k3MEnglish
    0•11 months ago

    Maybe watch this video by MirageC https://www.youtube.com/watch?v=c6JmCdovE0U I don’t think your issue is extruder gears specifically, but the video lists all the ways he eliminates other similar issues from an engineer’s perspective and your issue is likely in that mix.