Bed level changed with no printer changes



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    I have a custom DIY Kossel delta type printer modified to make it bigger and use 3030 extrusion instead of 2020. I have had and used it for a few years and all of a sudden the auto calibration is way off and never had issues with bed levelness in the past. It used FSRs for probing under the bed, has a duet3d wifi control board, and linear rails for the movement. I am guessing it is an issue with either one towers movement or an FSR issue but dont see anything that could be wrong. Belts are tight and fine, each FSR will trigger easily etc.

    Anyone have any thoughts on where to start looking basaed on the bed probing results attached?



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    I adjusted and ran some calibrations with just S4 and fewer prob points and that seems to have made it much worse...
    Some more info on the printer, it has the injection molded barbells and spring joints from SeemeCNC (https://www.seemecnc.com/collections/parts-accessories/products/replacement-ball-joints) so the spacing between top and bottom joints should all match. I am thinking it is an FSR issue and will start looking into those i guess



  • I may have found the culprit, I went back to my last backup of the config and config override file and that didn't help. But afterwards I checked each tower and if it is moving as it should. After measuring the X and Y towers are both moving 100mm when asked to but when the Z is asked to move 100mm it only moves about 96mm. Has anyone seen this before? how is that possible if all are using the same belts, same spec motors and M122 is not showing any step errors or anything. I am hesitant to change anything on the Steps per mm for just 1 axis if everything else matches for them...


  • Moderator

    First step would be to dig down mechanically and see if there's anything to cause that.



  • That's what I am trying to do but running into blocks, I visually can't see anythign wrong. Checked all towers are 90 degrees to the bed and all appear evenly spread. I did a slightly more accurate measure and after I removed and A,B corrections in the config override and reseting the printer the Z tower moved 49.22mm instead of 50mm and the X and Y towers move move 50.23mm instead of 50mm. Is there anything specific I should be checking mechanically, motor, idler pully, belt and carriage all appear fine?


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