Problems during check before starting print
I got a kit at the end of the summer, built it and got it working fine after some confusion about how to make evertyhing perpendicular.
At first I could just turn on the printer and do a print (did the calibration XYZ after I set it up), but lately (maybe the last 10-20 prints or so) there has been a recurring issue during the inital check over the nine points before putting plastic on the bed.
At first, it got past 6 or 7 points, and then I noticed it pressed the bed down at the back, and ended with a "Bed levelling failed (debris on nozzle?)" message.
First I was freaked out, but then I tried running the calibrate XYZ program, and after that the levelling passed and it printed everything just fine.
This would happen now and then, without me having moved the printer or done anything in particular to it. I always clean the bed with isopropylalkohol after having touched the bed in any way.
More recently, the printer has started to fail earlier in the levelling check, with increased frequency. It gets past the third point, and as it moves upwards it makes a sound like someone clearing their throat, stops and i get the debris on nozzle message. Running calibrate xyz made it work again.
But now calibrate xyz isn't working, and the last couple of failed levelling checks have left marks in the bed. On my final attempt just now, the printer really freaked out and pushed the nozzle down deep, bending the bed quite a bit.
The pinda probe looks to be where it's supposed to be. I can see plastic running out of the nozzle constantly, I try to remove as much as I can with the pliars before the nozzle reaches the bed.
If I do a calibrate Z by itself, there are no problems.
Looking at the underside, things seem to be in their places. Maybe it feels like it's a little bit more difficult to pull the bed along the y axis than it used to? I had a little trouble getting the rods in the bearing cylinders when I built the printer, and a few small balls dropped out. The printer makes a squeeking noise when it travels along the x axis.
Any ideas of where to starting looking for problems?
Re: Problems during check before starting print
Balls falling out of the bearings is never a good sign. They're basically broken now, that does explain the increased resistance and the noise when trying to move the bed. Do get some new bearings and replace all three of them in your bed.
However, it doesn't really explain your z-axis problems.. When the extruder moves up or down, is one side moving faster than the other? Is it moving smoothly or is the some binding/grinding/skipping going on? When you move it all the way up, do both sides hit the Z brace on top at the same time?
Maybe you can upload a short video to Youtube so we can see what's going on?
Re: Problems during check before starting print
On the right had side (the X idler) there are a couple of adjusting screws. It these are too tight or too loose, you will have additional resistance there.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Problems during check before starting print
Thanks for the replies guys, I've been knocked out by a cold for a week, I'll get around to shooting a video soon.
As far as I can see, the different sides of the rod that the extruder is hanging on are moving at the same pace.
I will follow your advice and change the bearings on the bed in due time. Note that it was just the bed bearings I had problems with, the rods slid into the bearings on the extruder just fine.
/Stefan