XL fully assembled fails Z calibration.
I got through most of the first time setup easily and without issue. When I got to the Z calibration step, I heard the motors make a strange noise when they first started moving. I have not heard this noise since then. The X and Y axis motors made a similar noise when they first moved and they are working fine.
Now I am stuck on the Z calibration step. I have tried running it several times and it behaves the same way each time.
When the printbed moves to the bottom, it is level and there are no gaps between the printbed holders and the motors.
When the printbed moves to the top, the left side stops about 5 mm before the top and the right side stops about 3 mm before the top, tilting the printbed. In this state, the display says the z position is -1 mm.
There is a noticeable gap between the nozzle and the printbed.
I do not see anything stopping the printbed from moving higher. The printer looks clean.
I do not see any limit switches or obvious sensors to tell the XL the bed's position.
What should I check next?
Here is a picture of the gap on the left side:
Best Answer by 420did911:
I found the problem. There was a loose screw I couldn't see, and another screw had fallen out during shipping. I found the screw in the box.
The screws were supposed to hold some metal piece on the bed and that part was keeping the bed from raising all the way.
I tightened the loose screw while holding the metal piece in place and now the bed raises like it should. I was able to complete a print and the print looks very good.
RE: XL fully assembled fails Z calibration.
I had a problem with the z-calibration too and found the solution here:
"Step 23 Semi-Assembled version only - Checking the Heatbed installation" in 7. First Run.
My problem was too much friction in the nuts driving the build plate up and down. following the instruction solved the problem.
Have a look at my models on Printables.com 😉
RE: XL fully assembled fails Z calibration.
Thank you! That is a good idea. I tried those steps and the bed still stops at the same position.
RE: XL fully assembled fails Z calibration.
One thing you could check is that the plastic parts at the top of the z axis are fitted correctly. There is a little lip that places (or should place it) in the correct location on the extrusion. However, it is quite easy for it to be misaligned (too high/low/off centre which I guess might have unexpected consequences.
Another thing to check is what happened if you manually twist the remaining 3-5mm and then maybe twist it down to say 30mm-50mm down - and then up again. Does it get progressively harder to twist the higher you go, or is it easy.
I guess if it’s easy then that might speak to an issue with a motor not having the power needed. If it’s hard, then I’d look at alignment issues in the bed or frame that is causing the friction to overpower the motor.
The under bed supports on the left and right can be bent - I had to remove mine and ‘encourage’ them flat. You know this if undoing the four screws the supports ping out of alignment with the holes in the frame.
RE: XL fully assembled fails Z calibration.
Short version: Thank you for suggesting the manual twist. That seemed to do the trick. Z calibration succeeded.
Long version:
Everything seems to be fitted correctly. I don't see any cracks or protrusions.
I turned the printer off and tried manually twisting the left side and it would not budge past the where it got stuck during calibration. I tried twisting the right and left sides to raise and lower them while keeping the bed level. I kept a level on the bed to make sure the bed stayed level. After about 5 times, the left side suddenly didn't get stuck any more. I don't know what did the trick, but the bed doesn't get stuck any more. I raised the bed back to where it was when I turned the printer off, then turned the printer back on and tried a full lower and raise of the bed. The bed raises just fine now.
I reran the Z calibration and it passed. I am continuing with the calibration now.
Thank you both for helping me!
RE: XL fully assembled fails Z calibration.
I spoke too soon. The rest of the calibration succeeded. I tried the bed level test from the included usb stick and the bed unleveled itself again.
I tried the manual twist trick again and after 30 minutes I could not get the left side to raise to the top. It still gets stuck at about 5mm from the top. The right side raises all the way to the top.
I tried raising and lowering the right side a few mm then trying the left side again, but the left side does not budge once it gets to that 5 mm spot.
RE: XL fully assembled fails Z calibration.
If you have a straight edge lay it across the bed diagonally and see if the bed is bent. I had the exact same issue as you and it ended up being a best/warped bed. Took a week to get QA to agree and authorize the replacement.
RE: XL fully assembled fails Z calibration.
How straight does it need to be? I placed a ruler on the bed diagonally and I can see light coming through little gaps between the bed and the ruler in several places. The gaps are much less than one mm. The shadows of the toolheads made it a little hard to tell, so I used a portable led light. I did this while the bed was room temp (about 70 degrees F).
RE:
I'd say, less than 0.5mm should print -- at least on the MK3S+. I am still waiting for the XL. Depending on how accurate you want your parts to be I'd try to make it better. You can measure gaps e.g. with a (non-magnetic) brass feeler gauge. A standard sheet of 80g/m^2 printer paper is approximately 0.1mm thin. If you really want to know it, you can try aluminum foil which is approx 0.02mm thin. On the MK3S+ many use springs to be able to adjust the bed. With its 7x7 grid it is quite easy to get below 0.1mm at printing temperature. OTOH, I have not yet read anything about an XL-user adjusting all the tiles of its large headbed.
When you use a spirit to see, whether the bed is horizontal, please do not forget to verify, that the x- and y-rails are horizontal as well. A mason's spirit might not be precise enough. A machinist's spirit ususally is an order of magnitude more precise (and expensive).
When you rotate the z-spindles manually into its ends, does it feel rigid or kind of soft? A potentially not correctly assembled cable chain may start to become overstrained.
RE: XL fully assembled fails Z calibration.
I found the problem. There was a loose screw I couldn't see, and another screw had fallen out during shipping. I found the screw in the box.
The screws were supposed to hold some metal piece on the bed and that part was keeping the bed from raising all the way.
I tightened the loose screw while holding the metal piece in place and now the bed raises like it should. I was able to complete a print and the print looks very good.
RE: XL fully assembled fails Z calibration.
I had a similar issue and Support helped me find that I had installed the bearings upside down at the top of the corkscrew bolts (not sure what they are really called). I see your issue was already answered, but just posting my find to a similar issue here in case someone else made the same goof I did.
CJ