RE: Y-axis self test failing consistently
Just discovered the same problem, y-axis calibration failures with no obvious cause. I built my MK4 about 14 months ago, haven't had much need for re-calibrating once it was up and running. Just upgraded to MK4S, and it began failing on the y-axis calibration tests. Read these posts. Checked my y-axis bearings. Sure enough, the front left bearing had crept backwards a bit. Loosened its screws, nudged it into position, re-tightened the screws. Re-ran the calibration and its right as rain.
RE: Y-axis self test failing consistently
Same issue here. Zip-tie method did the trick!
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My oldest son and I assembled our MK4 kit per the instructions flawlessly; the frame was aligned on a sheet of plate glass to less than one thousandth clearance on each corner, verified with feeler gauges, all metal-to-metal/frame fasteners were secured with blue lock-tite for longevity, all belts and fasteners tightened to ideal spec.. I work for the United States Postal Service as a mail process equipment mechanic (I troubleshoot, repair, and maintain a wide variety of mail sorting machines), so I am quite experienced with these types of mechanical and electronic systems and components. I'd confidently hold our assembled unit up against any factory assembled unit.. and it's printing right now with a zip-tie on the left z-axis rod to correct this firmware oversight.. We have some colorful expletives at work for hacky work-arounds like this. Haha..
Customer impressions of the brand and product are being needlessly harmed by these erroneous test failures, inept tech support, and silly zip-tie fixes. The y-axis values in the firmware are clearly inconsistent with the hardware/assembly instructions and need to be corrected asap.
The real problem is that a linear bearing suspended on a rubber dampener, offset by 85mm from the drive assembly, is not an appropriate bump/end-stop; this linear bearing will inevitably shift over time with all these calibration/testing impacts, and impacts produce a large unnecessary momentary force at impact on the carriage, bearings, rods, and frame. The y-axis end stop needs to be a flat plastic carriage-mounted piece in-line and centered just above/around the drive belt. It should touch the flat area of the frame evenly at the travel extent. This will eliminate needless bumping/scooting the linear bearing, finicky bearing placement during assembly, and also minimize the unnecessary momentary forces imparted on the components when reaching the travel extent. I'll be redesigning the forward portion of the y-axis carriage belt holder assembly to also serve as a bump-stop and will see about posting the model on here once I've tested and am happy with it.
I've got to say though, the print quality is incredible. I don't have much experience with 3d printing yet, but an experienced co-worker was bewildered at the quality of our prints, and compared to prints I've seen elsewhere and pictures online, ours are really very nice. It seems like a great machine overall.
RE: Y-axis self test failing consistently
I had my 15 year old running the calipers, so no promises on the OAL yet, but I'm currently printing off a modified Y-belt holder that will also serve as a proper end-stop to the frame (no more ugly bearing clunking). Here's the STL file, although the length may need to be dialed in a bit after testing.
https://www.uploadlite.com/d/JiTrIrwxXZdc3s
Looking forward to removing that silly zip tie. Haha...
RE: Y-axis self test failing consistently
I made a couple of changes for frame clearance, and for ease of printing. The new Y-belt holder printed off nice with no brim or support material when placed on the long side. Installed nice and the y-axis calibration passed with no more zip tie needed. That poor linear bearing will be much happier going forward too. Haha..
Here's the STL file:
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And why didn't you add an adjustment screw to the face to allow the exact distance to be set? Maybe like this? Add an M3 x 20 mm screw to the part. Screw the screw directly into the hole in the front of the part, no nut is needed, the screw holds relatively firmly directly in the plastic. Alternatively, you can add an M3 locking nut to the face. Enjoy!
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guys, thanks so much. I checked my carriage bearings and indeed the "bumping" managed to move them inward enough to fail calibration. Reset them as per assembly instructions and all is back to normal. No zip tie needed. Yet another "regular maintenance check" item: after "regularly tighten all screws", "visually check carriage bearings' alignment".
RE: Y-axis self test failing consistently
Mainly I was worried about a metal-to-metal end stop for it; the flat part touches the metal frame plate at the front at travel extent, which might scuff up the paint and would make a 'tink' sound instead of a 'thud' when it's calibrating. Could easily be solved by cutting and sticking one of the rubber pads on the end of the screw though.
RE: Y-axis self test failing consistently
Solved the dreaded 211 problem. Thank you. Thank you.