Hard fail during XYZ calibration
Back story: Got my kit two weeks ago. Assembled and tested fine. Failed during a print ending up with a blob. Cleaned the blob but broke the thermistor wires. Got replacement parts last Friday and reassembled and tested. Ran a couple test prints OK. It then failed with a "Crash detected" message on the screen, and started printing in a completely wrong part of the print bed, thankfully during the first couple layers while I was watching. It appeared as though it completely lost track of the X axis location. It would not auto-home to actual home. I turned it off and went through the pre-flight stuff again, and restarted calibration.
I have not been able to successfully get through XYZ calibration since then. Sometimes it will appear to lose track of the X axis location again, searching for a calibration point in a completely wrong location. If it even makes it through the first run of all four calibration points, it fails HARD on the improvement of point 2 where it just rams hard into the heat bed and won't stop trying to move down, as if it has forgotten where the Z location is.
The pinda appears to be working well, as the LED flashes off as it detects the calibration points, and turns off when I put a metal object near it. After this happened a few times, I gave up and called it a night, tried again this morning, and took a video, since that appears to be helpful (and requested or required most of the time).
Firmware is as shipped, v3.1.3-245. I looked into trying the RC 3.2, but saw plenty of calibration problems with that, so didn't bother yet. I've also been reading through other threads, but haven't yet found a problem similar enough to mine to help.
Thank you for reading and offering any assistance!
- Greg
Re: Hard fail during XYZ calibration
Looks like your X-axis is not perpendicular to the Z axis. What happens if you put the nozzle very close to the bed on the left, then move the X-axis manually to the right side... is it lower? If so, either your z-axis is not calibrated, or it is slipping. Do both Z-motors turn freely? Maybe try just a Z-calibration to see if that helps.
Re: Hard fail during XYZ calibration
It's as perpendicular as I can make it prior to calibration. I follow the guide in the pre-flight part of the manual, just as I did when I first assembled it. Everything seems to run freely, but I do hear some sounds (clicking or scratching) I hadn't heard before. I can't figure out where they're coming from, though. I checked the tension on the belts and all the set screws, and everything checks out as far as I can tell. How can I tell if the Z axis is slipping? I didn't even know that would be possible with a worm drive like that.
Re: Hard fail during XYZ calibration
Probably not your case but might be useful to check. In my case the scratching noise was coming from dust that got stuck to the z rod and the bearing was making that scratching noise and most importantly it was affecting the z movement. Of course creating tiny perpendicular issues.
Re: Hard fail during XYZ calibration
I don't think that's it, either, but anything is worth exploring. Think I should put some lube on the bearings? I have a pretty good variety of light lubricants. Some other threads seem to indicate that it's not needed, but doesn't hurt, other than the likelihood of needing to keep lubricating over time. I've got some stuff that lasts a nice, long time, and is really light, that I might try, if there seems to be a good reason to try it.
It sure seems like a firmware or motor issue, though. I'd blame the probe, but it seems to be working fine. When the calibration fails and the print head slams into the heat bed, the probe is not over the calibration point as I would expect it to be. It seems like the extruder assembly has been moved too far, or nor far enough, and/or it has forgotten where the Z location is and just wants to keep moving the print head down through the heat bed.
Hopefully I can get some help, soon. I'm about to start pulling my hair out. The whole reason I went with Prusa was the promise of easy/automatic calibration and mesh bed leveling. I could have saved hundreds if I knew I'd be dealing with this crap, anyway. 🙁
Re: Hard fail during XYZ calibration
I am having the same problem and others at this point. I have had my MK3 since Jan and it has been printing pretty good so far. I was going through updating parts to the latest rev of the printed parts and color matching everything else to them so I took the motor mounts off, the bed off etc but I did NOT monkey with the frame.
Now the printer will not complete an XYZ calibration, it is either telling me "Bed calibration point not found" or it goes through 1 to 3 iterations and fails with a "Consult Manual" error.
I have been on FW version 3.1.3 since shortly after it came out, I tried upgrading the firmware to 3.2.0 RC2.534 and received the "Bed calibration point not found error"
I have performed the Selftest over and over, Rest the calibration, step through everything in the Pre-Flight multiple times.
The extruder appears to be off to the right consistently through the process by approx. 10mm which on the right side of the bed means the sensor is moving off the bed completely.
This is driving me bonkers, any suggestions?
As a side note, turns out that pretty good was not sufficient to print the new parts with the tighter tolerances.
Re: Hard fail during XYZ calibration
Wow. The "10mm to the right" is pretty much exactly the problem mine appears to have. You can see at the end of the video that the Pinda probe is pretty much 10mm to the right of where the calibration point is, which explains why it's trying to push the print head through the heat bed. This certainly doesn't make me want to change the firmware, but I'm still on what it shipped with (see OP). Hopefully we both get some answers soon. It's pretty sad to have this investment just sitting there, not working.
Re: Hard fail during XYZ calibration
I'm 10mm to the right no matter the version of FW. I downgraded back to 3.1.3 which I had been on for a month.
I just went through and made sure my Z-Axis was all lined up and in good shape with all the parts I had used previously for 3 months and the XYZ calibration went through the first four points nearly on target each time and then on the second iteration lost it's mind and shifted 10mm to the right again ultimately slamming the nozzle into the bed again on the second calibration point.
Re: Hard fail during XYZ calibration
Even more accurately describing what happens for me. First iteration is fine, and then second iteration fails on point 2, 10mm to the right, and slamming into the head bed.
Hey, we're Prusa-failure-bros! 😉
Re: Hard fail during XYZ calibration
The issue with calibration on 3.2RC2, is they changed the sensitivity of the PINDA probe, and if it was too "high" it will cause the nozzle to crash.
I would try 3.2RC2 as it has a totally new calibration routine compared to 3.1.3
Is there any chance you could upload a video which includes the initial "bump" calibration? (where it bumps the X side with the motor ~10 times)
I'm not sure why it would only happen on the "improving" step. There's something going on, and it's happening BEFORE it crashes. The question is why?
I wish I had a 2nd mk3 I could use for "helping"...
@Prusa: HINT HINT HINT
I'm almost thinking it's like the X axis is getting jacked up between Point 3, and point 4. on the calibration, or sometime even before that? I would have to see the entire calibration run though to make any accurate guesses.
I'm specifically thinking about the pigtail on the back of the extruder assmebly. I am SUPER curious about the initial X calibration, where it bumps 10 times. Is there a zip-tie hitting the frame, or a wire?
Hi, I'm Sean. I used to work on CNC machines.
I try to not make mistakes, but the decision is YOURS.
Please feel free to donate to my filament/maintance fund.
Re: Hard fail during XYZ calibration
Sean, I created video from start to power down at failure. It is 10 minutes log and quite large because of the resolution so I am hopefully going to be able to put a link in here for you to see it.
https://photos.app.goo.gl/gLfZDYobwSS92WCi8
Lew
Re: Hard fail during XYZ calibration
There's something wrong with the x-axis home. It "hiccups" several times during that initial home set. Some kind of friction is fooling the stall guard and as a result it does not have an accurate home position. What about that wire loom off the back of the extruder- that looks rather stiff to me? Check the x axis for drag, bearing alignment, and double check the zip-ties on the extruder. They get VERY CLOSE to hitting the einsy case and/or frame.
Re: Hard fail during XYZ calibration
Reid, thanks for the insight. I just wasn't seeing it. You got me pointed in the right direction. At least in my case it was one of two things.
I corrected that
Apparently that also was a bad thing so I put the original ones back in.
It is now calibrating exactly correctly and dead on target. I even upgraded the firmware to 3.2 RC2 and it worked perfectly as well.
Re: Hard fail during XYZ calibration
AWESOME! Good sleuthing sir!
Re: Hard fail during XYZ calibration
Just a quick follow up, since I apparently forgot to post it in my own thread. The resolution for my problem was loosening the screws of the back plate on the extruder assembly. Apparently, I had snugged them down pretty well, which was tweaking the linear bearings enough to cause binding, messing up the X-axis motion, causing it to fail. I backed them all off about a turn, relieving the pressure on those bearings, and it moves smoothly again.
It's interesting that the manual is clear about not overtightening the screws on the Y-axis (build plate) bearings, but neglects to mention it for the X-axis. When I rebuilt my extruder assembly after my other problem, I had forgotten about that note, and snugged them up pretty hard. They really should put a note in the assembly guide about that. I wonder how many other calibration and printing problems are down to tweaked bearings.