RE: Constantly recalibrating
Ok, I let it bang away for three minutes. It returned an error "Axis Measurement Failed" and then started printing. This is an insane amount of time to have any kind of machinery crashing around in it's boundaries trying to calibrate. And why would it start printing if the "axis measurement failed"?
The test keychain did print fine, with an overall print time of 15 minutes, 23 seconds, including the three minutes of crashing around in the corner.
RE: Constantly recalibrating
Just updated to the 6.3.1 firmware and my home calibration problem seems worse. The banging goes along for a long while, finally fails with multiple error messages including y calibration failure and collision detection (same as others have reported), but then still prints, and prints seem Ok. Running the y axis test manually also consistently fails, but all other tests succeed. Went through the belt tuning exercise (both sides at ~85hz). Prior to the firmware update, the banging would last no more than 20 seconds with no error messages (still annoying, but more tolerable than one it's doing now).
RE: Constantly recalibrating
Followup: Fiddled with belt tension again (84hz), and got y calibration test to finally succeed. Homing also seems back to normal. This seems to be a very finicky aspect of this printer (and perhaps all core xy printers, as this is my first). Some kind of auto belt tensioning mechanism would be a welcome improvement in future versions.
While the Core One is noticeably faster than my old MK3 once it gets going, it seems like a lot more time is spent getting ready to print.. absorbing heat (skip-able I know), 49 point calibrations, sometimes followed by another smaller count calibration, nozzle cleanings, etc... it sometimes feels a bit slower overall.
RE: Constantly recalibrating
So I let things sit for the evening. In the morning I re-ran the X, Y and Z calibrations. I've had two prints start correctly now, where there is a couple quick bounces on the right side of the x axis, a couple to the front on the Y, a few bounces diagonally between the two, and it's off to the races. The spatula from the USB drive printed well, and I just started a 5 hour print that started cleanly and has been running well for most of an hour.
I did not consider the pre-start time of letting the metal frame acclimate to the internal temp as well, but this is countered by the fact I can print more materials and significantly faster than my old MK3. Overall a big plus for me. Just wish I had room for another one.
RE:
I'm still running into this issue and expect to hear back from Prusa support around 4/29/25 at the latest based on my last support chat. I've played with the x-axis making sure is not skewed. I made sure the belts were tensioned to 85/86Hz and the issue persists and I'm just not sure if they need to be tightened, loosened, or if the belt tension is even the actual root cause.
While I'm far from a 3D printing expert, my observations and what I expect to happen (without knowing what's going on under the hood for calibration) is its not detecting whatever the front/right boundary is to set to the "max" value. I have no idea what sensors are involved in performing this calibration or why it feels the need to recalibrate/home before every print but here's what I've noticed so far.
After a fresh re-install and belt tension adjustment, the Y axis calibration was having this same issue where upon first assembly, it was my X axis. I've had both axis tests fail frequently when the extruder is close to the upper bound (somewhere in the ~240mm+) where it keeps banging against that extreme rather than realizing that is the boundary and it should go in the opposite direction. I've had better success making the calibration test pass (still not 100% of the time) when manually bringing the extruder to 0,0 and starting the calibration as it seems to move toward the larger number boundary first. My thought here was it can detect that it was able to move x number of steps in the positive direction, so it should be able to go at least that in the opposite direction.
Although that "trick", if you will, helped the calibration steps pass, I'm still faced with the printer being stuck on calibrating home before every print as seen in this post by another user:
https://www.reddit.com/r/prusa3d/comments/1jdr7h3/core_one_stuck_calibrating_home/
Hoping this information helps find a resolution for us all. Buying a printer in January, delivered in April, putting it together...I'd really like to enjoy it at this point. I'm open to the issue being my fault somehow during assembly, but I'd really like a more definitive answer/resolution before I start disassembling everything just to try it. FWIW, my first chat suggested its a firmware issue that needs to be fixed with no ETA and the second chat is the one I'm still waiting for a response on after they reach out internally.
RE:
Newly arrived printer for 3 days now, pre-assembled, batch 9, version 6.3.2+10364. Belts are 85 - 88Hz.
Mine is also constantly recalibrating, appears to always be from second print onwards.
Always works fine on first print after power on, or after a reset.
Had it running for 5 minutes at one time, with errors being reported about an obstruction, before I reset the printer.
I have to do a reset when it happens, as stopping the print does not stop the homing.
RE: Constantly recalibrating
Dear Prusa Support Team,
I bought a pre-assembled CoreOne. The belts were already tensioned to about 85 Hz out of the box, yet before every print the machine runs the calibration routine for one to three minutes.
- Why does the printer repeat this procedure so often?
- What tolerance or precision is it aiming for?
- Is there a parameter I can adjust to reduce the frequency or duration?
- Does a log file exist that records the details of each belt-tuning cycle?
If you need any additional information, photos, or log files for further investigation, please let me know and I will gladly provide them.
Thank you for your assistance.
RE: Constantly recalibrating
Dear Prusa Support Team,
I bought a pre-assembled CoreOne. The belts were already tensioned to about 85 Hz out of the box, yet before every print the machine runs the calibration routine for one to three minutes.
- Why does the printer repeat this procedure so often?
- What tolerance or precision is it aiming for?
- Is there a parameter I can adjust to reduce the frequency or duration?
- Does a log file exist that records the details of each belt-tuning cycle?
If you need any additional information, photos, or log files for further investigation, please let me know and I will gladly provide them.
Thank you for your assistance.
Sorry, but the Prusa support team doesn't actively monitor this forum. (Or if they do, they do it stealthily and won't respond.) You will have to send your inquiry to the support email address or chat to get a reply from Prusa.
RE: Constantly recalibrating
Same problem. Bangs against the x and y stops giving homing and crashing errors. It will go on for over 10 minutes sometimes it prints, usually it reboots and gives a "precise homing refinement failed" error. Tightening the belts is frustrating, the same adjustments set the left and right y axis stops, you can get the belts tensioned or set the stops but not both. I'm pretty disappointed so far.
RE: Constantly recalibrating
I bought a set of four anti-vibration pads for air compressors from home depot. I have not had issues with homing since I put them at the corners, under my printer.
RE: Constantly recalibrating
I cured mine by putting it onto the floor. A solid tiled floor.
It has calibrated first time every time since.
That's an excellent point. I have been wondering whether there is some other factor (besides belt tension and well-squared X gantry) which contributes to some Core Ones having such persistent problems with the XY calibration. Maybe this is it? While it seems that Prusa needs to revise the firmware to make the calibration/homing more robust, providing a solid base for the printer could be a workaround that also helps print quality.
My Core One has never shown issues with the XY homing -- it always does four to six "double bumps", i.e. driving into the X, then Y end stop. It sits on a very sturdy old desk at the moment, which resists shear forces well because it has an integrated drawer cabinet and bookshelf, with solid walls in the XZ and YZ planes.
RE: Constantly recalibrating
I have noticed the same situation - when I preheat the banging/recalibration goes on for a very long time and sometimes I have to shut off the printer and re-start the entire process. When I simply start a print from ambient temperatures there is only a short banging/recalibration process.
RE: Constantly recalibrating
Just received my pre assembled Core One two days ago. I’m having this same issue. Print head repeatedly bangs into upper right front corner before each print. Works great when cold. Gets worse after first print.
RE: Constantly recalibrating
i assembled the core one myself. I also run into this issue. It is my first 3D printer so i didn't know if this is normal behavior but apparently not. keeps banging the corner for minutes until it starts printing. It is actually loud and annoying.
RE: Constantly recalibrating
Confirmed!
I think the two rubber dampers that came with the printer were the problem. Maybe I placed them incorrectly at the bottom of the device. I removed them, and voilà – the long recalibration process is gone!
Thank you for the advice.
RE: Constantly recalibrating
I also had this problem with my MK4S to Core One conversion kit. I resolved it by re-tensioning the belts. The key seemed to be to make sure there was no gap between gantry and the front of the printer when it is pulled to the front-most position. Also I found that tensioning one belt would affect the other one, so making very small adjustments (1/4 turn each time) on one side at time, then checking both sides was essential. I used the Prusa app on my iPhone. I ended up with one belt at ~85hz and the other at ~89hz. If I made them exactly the same there was a gap at front and the constant recalibration kept happening.
RE: Constantly recalibrating
Mine is doing this as well. It just bounces back and forth over again. It sounds and looks terrible so I've never let it run out to 5 or 10 minutes, but it'll certainly bounce back and forth for a minute sometimes. I hit reset and try again and it'll work fine the next time. Something is not consistent.
I'm not excited to start tinkering with the belts right off the bat so will need to check in with support.
RE: Constantly recalibrating
Hi, I am on version 6.3.2 of firmware and have adjusted the belts using the Belt Tuner and have tried tightening them further but it continues to bash on the right hand side for minutes on end. It seems very variable and not possible to predict. Even happening on a filament change.
I can see no reason for this constant banging of the head?
Any fixes in the pipeline.
RE: Constantly recalibrating
This is so frustrating and I am shocked that this has been an issue for 3 months now. I'm also in the same boat as many others, and it makes me not want to use my Core One for shorter prints, because my old MK3 is literally faster. I added dampening feet and for three prints it seemed fixed. The next day, it started again, despite me not even touching the printer in the meantime.
I am using a preassembled printer, and also tuned my belts already.