Coreone+ collision detected.
I know this has been discussed many times, but it is beginning to really frustrate me. I have today spent over an hour trying to start a print, but I keep getting the "Collision detected" error message. I've checked for debris on the smooth guide rods and the screw rods, and I've re-checked the belt tension. The one other thing the error message sometimes tells me to do is "reduce the sensitivity in the control menu" -- but I can find no sensitivity setting.
When I start a print the X/Y calibration proceeds normally (I think) with the carriage hitting the right front ends about 5 times, but the print plate then comes up in stages until it hits the nozzle and then backs off a few mm. It then creeps up again until it hits the nozzle again, and then repeats a few times until the error message is displayed. Same again when I press the "Continue" button.
All the individual tests/calibrations show green tick marks, and when I eventually get it going (so far I haven't today) the print results are excellent.
RE: Coreone+ collision detected.
Well, after posting this and making a cup of tea I returned to my printer and re-commenced the print, and everything performed correctly 😮 I made no changes -- just re-started the same print I'd been attempting for the past hour or more. So why does it happen, and where is the "sensitivity" setting that the error message sometimes mentions, please?
RE: Coreone+ collision detected.
I'm not an expert (only had mine a little over a week) however what you describe seems almost normal, except for one thing.
The print plate doesn't normally move up in stages, it moves up in one smooth continuous motion until it contacts the nozzle once, then it backs off a few millimetres like you describe and then slowly contacts it a second time, and then the process is complete.
Recently while the bed was moving up I wiped some gunk off the nozzle and I noticed that when I touched the nozzle the bed stopped moving upwards. I briefly touched the nozzle a couple of times and the bed briefly stopped moving each time.
I think what was happening is that when I touched the nozzle, the load cell thought the bed may have contacted the nozzle and slowed down, but when I let go of the nozzle it thought oh it must've been some plastic debris hanging off the nozzle that has now been pushed out of the way, I'll keep moving the bed up until I get a stronger reading on the load cell.
In your case I wonder whether the load cell is not reporting accurate values? Have you tried redoing the load cell calibration? I found when I calibrated the load cell and it told me to tap on the nozzle, I had to tap very hard for it to work. I wonder if you tapped too softly whether it makes the load cell too sensitive? Maybe try recalibrating the load cell and making sure you tap the nozzle quite firmly with your finger, and see if that changes anything.
Also, I had a firmware crash by trying to hold the knob down and adjusting the bed during a paused print, and when it rebooted it made very strange noises when trying to adjust the bed height. It seemed to have forgotten where the bed was, and would raise the bed in small increments at a time. I fixed this by performing a Z-axis calibration, which moves the bed all the way down so it knows exactly where it is, then it moves smoothly up again, so you could try redoing that calibration operation as well.
RE: Coreone+ collision detected.
On some Core One printers, the hotend heater interferes with load cell sensing, causing spurious signals. Your experience of the stop & go Z homing may be caused by that -- did you have pre-heating active at that point maybe? Another typical symptom is that the mesh bed leveling is slow, with the printer tapping many points more than once. I am not sure I have seen reports of spurious crash alerts due to this problem, but it would make sense that false load cell signals can also occur while a print is ongoing and the nozzle is being heated.
For those who have reported the problem here, it seemed to typically be pretty persistent and reproducible. So I am not sure what to make of your observation that it worked fine the next time you tried. Maybe something has shifted within the main cable harness? (That's where the crosstalk seems to occur. Prusa support has provided replacement cables to users with persistent load cell issues.)
If the problem recurs, I would contact Prusa support. Maybe a replacement part is needed.
RE: Coreone+ collision detected.
Thanks Milvineous and Jurgen.
I've only had my Prusa a couple of weeks. IIRC from the outset the bed has always moved up in stages. Certainly, touching the nozzle causes the bed to stop where it is, which is understandable. I've ensured the nozzle is visibly clean, and I've gone throught the nozzle detection test many times, always with a pass. Passes also for all the other tests in the menu. To this layman the puzzle is why the bed has so much trouble during the initial calibration routine, yet always (so far) has no problem once it moves on to the multi-point bed detection routine -- up to 49 points with some of the prints I've been doing.
My printing thus far is with PLA, and I don't manually select pre-heating. I'll get in touch with Prusa support if no other suggestion cures the problem.
RE: Coreone+ collision detected.
I've been in contact with Prusa support for about a week now, trying out several tests and suggestions. We've got to the stage where they send they'll be sending me some replacement parts, one of which is a cable harness.