Convex bed, any idea how to solve?

  • Hi all, I am having problem with my old printer bed. It is a prusa style printer with glass bed directly supported by three screw connected to the bed by three magnets. the glass seems convex and this problem is present even without heating element connected so it seems a problem with the glass itself or with the Y carriage.
    Any idea of what may be the cause ?
    0_1555702341471_newplot (1).png

  • did you check the glass bed with something straight like a ruler or so?

    it could also be sagging due to the weight of the x carriage.

    what rods do you have? direct driver with stepper motor on it?

  • thank you for answering me.
    This is a photo of the carraige , now has regulation screw in different position , 2 on the left and one on the right , but I don't think it is the cause of the problem.

    0_1555704900972_20190317_111128 (Small).jpg

  • Moderator

    Definitely looks like sag on the X axis. You can verify by rotating the bed 90 degrees and re-running the bed map. If it looks the same, you know it's the rods and not the bed.

    Mesh compensation is a good way to counteract it. Just make sure to disable the taper so that it persists all the way up the part.

  • thank you very much .
    I am gonna check the bed , maybe I can try to buy another one , it is simple 4mm glass , so not a big deal and I still can use as a spare.
    Also I 'll check the road if bended. Do you think I can exclude Y carriage as the cause ?

    Mesh leveling works better after I am switched from Marlin to Klipper , i like this firmware very much and gave at this " old" 8 bit ramps based printer a big pimp 🙂

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