I have a printer I have basically built. It is a tronxy frame (and corexy motion), but over the years I have added linear rails, a duet 3d control board, quad zscrew independent leveling, a zesty nimble extruder, and other things.

My printer was down for 6 months or so, a new kitten we got ate some wires and it took me a bit to get the motivation to rebuild it. It turned out just a couple of things got unplugged and I was quickly back in business.

Ever since starting printing again I noticed that my tolerance has been off and it seemed to be over extruding quite a bit. I tuned my steps per mm, and driver power on the extruder motor to no avail. Eventually I replaced the motor and the nozzle (which was perfectly in check but if I was going that far I figured why not). It seems to have solved the problem… Sort of.

I have been using the prusa procedure to test and tune extrusion multiplier: print a 40x40x40 cube in vase mode, and measure the wall thickness. My extrusion width is .45mm, and until today I was getting a width of .52-.54mm. the replacement parts have cured this, if I measure in the right spots with my micrometer I get .45 exactly. But I have these bands. If I measure the high spots on the bands I get the same .52+ mm.

I looked at some of my old test boxes:

I have the same bands but different patterns.

A little googling and someone suggested (for a similar problem) that belt tendon was unequal. From what I can feel my tension seems to be the same.

I’m printing a tolerance test now to see if my issues are fixed, but I only feel 50% confident. Does anyone have any advice as to what might be going wrong? My belts have been on the printer since upgrading to linear rails and could probably use changing… But hopefully someone else has an idea?

  • _thebrain_OPEnglish
    3·
    2 days ago

    Everything runs on linear rails, since it is corexy the y axis has two, the rail where the extruder rides has one, and the bed has 4 linear rails on each corner. I will hit them with some lube tomorrow and see if it helps.

    • beeb@lemm.eeEnglish
      3·
      2 days ago

      What is driving the bed height? Lead screws? Check if they are straight and/or wobble around as they turn. Any imprecision in bed height due to mechanical issues with the Z axis would also translate into perimeter width variations.

      • _thebrain_OPEnglish
        2·
        2 days ago

        Each corner of the bed has a linear rod running up the clot, a lead screw in the middle, and then a had mounted 8 mm smooth rod on the other side.

        My thought as well is I have a bent screw or something out of alignment but the bed feels like to moves without shifting back and forth.

        Also, the frequency of the banding is different each time, even though I am printing with the same speed and settings each time.

        I do have two different lead screw couplers on it (the spring style and the one with the rubber star in the center). I have the parts to make them all the same., so maybe I will give that a try and check my lead screws alignment at the same time.

        Any recommendations on an anti-wobble nut that is printable or inexpensive?

        • beeb@lemm.eeEnglish
          1·
          6 hours ago

          I’m afraid I can’t recommend anything as I’ve never had issues with this, so I never really researched it. But if the banding frequency changes from print to print, then an issue with the Z axis is unlikely