RE: Printing head calibration going wild
- if you start a print and then it's going crazy with calibration errors, nozzle cleaning errors and probing errors: look up for the custom G-Codes that disable the hotend heating for these steps in the Custom Start G-Code. For me that solves all these issues.
M104 S0 ; disable hotend heater
Whilst I understand the overall thought behind your post (fix it rather than take legal action) - it's a bit much to have to go to the lengths of disabling lots of features that you're paying for on a ~£1000 printer. The 'much vaunted' Prusa support should be encouraged to either fix it themselves (in the case of an assembled printer) or come up with fixes for the customer to implement (in the case of a kit).
RE: Printing head calibration going wild
I have to say, given my original reasons for starting this thread (I was set on getting a core one but whether to pay for the assembly or go for the kit) having read about the 'print head homing' issues here and on other threads I'm seriously re-considering buying one at all. I know it's easy on a forum to 'disappear down a rabbit hole' and lose perspective over one issue that's maybe only affecting a small percentage of customers but Prusa's apparent lack of action over this is concerning.
RE: Printing head calibration going wild
oops ... I got confused - I didn't start this thread I started a different one 😳 https://forum.prusa3d.com/forum/prusa-core-one-general-discussion-announcements-and-releases/core-one-kit-or-pre-built-2/#post-756577 and I can't edit my post now - apologies to the OP.
RE: Printing head calibration going wild
Although understanding your frustration, it might be easier to get it to work, than keep being as frustrated, as you are.
- when you switch on the printer. Is it already giving errors or only when you start a print?
- when you just switch it on and wait until it's ready (no preheat!). Does it also fail the "Auto Home" from the LCD menu? (Control - > Auto Home)
- if you get it to switch on and boot up fine, the Auto Home without preheating works fine too and your belts are between 80-110 Hz, your printer is ready to print.
- if you start a print and then it's going crazy with calibration errors, nozzle cleaning errors and probing errors: look up for the custom G-Codes that disable the hotend heating for these steps in the Custom Start G-Code. For me that solves all these issues.
M104 S0 ; disable hotend heater
Put that before the G28 command, the short G29 command without a comment (it's the nozzle cleaning) and before the G29 command-block for MBL.
Dear RaazThanks for the help, I've already tried everything, but I'm not willing to write G codes, to solve the Prusa problem.I paid full price for a working product, but this one doesn't.Oh, and by the way, my money was with them for almost four months.The support is also completely clueless, they didn't even offer to fix it under warranty, when I asked about the repair, the answer was that I have to pay the labor fee of 30 euros/hour. Unheard of and ridiculous.
RE: Printing head calibration going wild
Can you please elaborate on what you mean by “had plenty of room to move around”? Do you mean rotation and / or axial movement? Did you simply back off on the screws?
Also you mention using a tension meter to measure the tension. What did you use?
Thx!
RE: Printing head calibration going wild
Same problem here:
It takes several minutes and it happens before the actual print starts. The belt tension is set to 85 Hz (left) and 87 Hz (right). Printer calibration process had been completing successfully before.
I need to get in contact with the support.
RE: Printing head calibration going wild
If you don't want to spend time with the support:
Without pre-heating, does the "Auto Home" from the Control menu on the printer work fine and only bangs about 8x in the corner?
If yes, set your Slicer to expert mode, then printer settings, custom G-Code - > Start G-Code and search Google or the forums for "M104 S0". There will be posts by me and other users, how to disable the hotend heating during homing, nozzle cleaning and probing.
Apparently, the heater and the loadcell share their ground connection, resulting in wild loadcell values during heating, including just keeping the temperature.
This can be worsened with a pinched or damaged main cable to the print head. And someone also had a damaged load cell. But then the Auto Home without pre-heating should be unreliable too.
RE: Printing head calibration going wild
Without pre-heating, does the "Auto Home" from the Control menu on the printer work fine and only bangs about 8x in the corner?
I did not check this before reaching the customer support. The support suggested me to check the alignment of the CoreXY structure. It was off only a fraction of a millimeter on one side. However I couldn't fix this while having the same tension of both the belts. Because of this I loosened all the screws of the frame and then re-tighened them again. After that the alignment of the gantry was perfect.Now the printhead still hammers a few times, but it is way shorter now (only about 10 seconds).
Obvisouly the frame was not aligned in a 100% perfect right angle. I had tightened them during the built before the side plates and covers.Now with the covers and side plates the angles seem to correct themselves if you loosen the screws a bit.
RE: Printing head calibration going wild
Yes it seems to be more stable when cool. I adjusted the belts one more time and it seems to have settled down to 7-8 bumps. Yesterday however after a nozzle change it was having trouble completing the nozzle cleaning. I wonder if it’s related to the grounding issue. Thanks for the tip I will check it out to see if it’s applicable here.
RE: Printing head calibration going wild
I had the same problem, head keeps banging for a minute or two at the front-right corner, but it stopped on its own and continued with the print. Will see if it will do the same in next print or it's a one time thing.
This is definitely a 'sick sounding' and an unexpected behavior from a 3D printer and if it's normal, Prusa should make it clearer, e.g. by showing some progress indication.
RE: Printing head calibration going wild
Yes it seems to be more stable when cool. I adjusted the belts one more time and it seems to have settled down to 7-8 bumps. Yesterday however after a nozzle change it was having trouble completing the nozzle cleaning. I wonder if it’s related to the grounding issue. Thanks for the tip I will check it out to see if it’s applicable here.
I'm swapping nozzles every few days between 0.25, 0.4 and 0.6 mm.
I also got some "endless banging" every now and then, even with the heater disabled for Homing/Cleaning/Probing.
The issue is putting constant stress on the loadcell via the hotend cables and thumbscrews.
For me, the solution was to loosen the thumbscrews really only as much as needed to get out the nozzle.
The thermistor cable slipped underneath them a few times...
But more important: Don't overtighten the thumbscrews (they really just need to keep the nozzle from falling out), don't "press" the nozzle all the way in, just "feather" it against the end-stop and lastly:
I sadly assembled the hotend without the nozzle changing tool already printed, so when using the tool, there's a lot of tension on the heater cable.
Therefore I don't use the nozzle changing tool and just tighten the nozzle with a bit-holder-screwdriver, while holding the hotend block in place with my other hand.
It's not super tight, but tight enough to stay in place.
I then only slightly keep the nozzle fully in by very gently pushing against the tip of the nozzle. The hotend rotates a bit during the last Millimeter of fully inserting, due to the tension of the hotend cables.
This makes sure, that there's no constant stress on the loadcell (you can get into the sensor information via the LCD menu, while the printer is on and monitor the loadcell value!).
RE: Printing head calibration going wild
I also absolutely don't know why Prusa thought it would be a good idea to annoy 99,99% of customers for 99,99% of prints , just to get an almost invisible seam, if a power outage happens.
This ^
This homing design is sloppy, banging the print head 50 times for a feature that I don't care about.
RE: Printing head calibration going wild
If your printer is banging more than a few times, your X gantry is not square.
Easily fixed.
The homing design isn't sloppy, but the design is quite sensitive to misconfigurations that will cause inaccurate (out-of-square) prints.
There's plenty of posts explaining how to correct this - loosen the belts, bend the gantry so it hits the stops at the same time on both sides, then re-tension the belts evenly (not all one side at a time).
RE: Printing head calibration going wild
M104 S0 ; disable hotend heater
I also got a massive head bang when starting the filament change function, I presume it does homing for some reason. Is it a known issue, any gcode workaround for it?
RE: Printing head calibration going wild
The homing design isn't sloppy, but the design is quite sensitive to misconfigurations that will cause inaccurate (out-of-square) prints.
Considering the number of people here that face this issue, Prusa should take serious look at this issue.
As for my printer, I am trying the suggestions here, and my first print was very good, once the head banging ended.
RE: Printing head calibration going wild
M104 S0 ; disable hotend heater
I also got a massive head bang when starting the filament change function, I presume it does homing for some reason. Is it a known issue, any gcode workaround for it?
That's a bit more complex and I'm not sure, if I'm remembering correctly.
When a print is done, the filament is retracted out of the nozzle, so unloading the roll can be done without heating up.
If you start the filament change option, it will heat up though and might cause issues.
The homing is done for the purging of the new filament not dropping onto a random spot.
G-Code workarounds won't work, you'd need to change it in the firmware.
What you can do though: before changing the filament, do the Auto Home from the control menu. This is done without heating and the position gets stored.
Then click on unload filament, take it out, click on yes, successful and then simply insert the new filament until it's entering the print head. The printer will detect it and ask you about the material.
A bit annoying, but it might work a lot better this way.
But as I said: if the Auto Home without heating doesn't work flawlessly, then it's a real issue and not just the loadcell signal being flaky (8 bangs in the corner and some double-bangs against the side and back before moving to the front right corner).
RE:
The homing design isn't sloppy, but the design is quite sensitive to misconfigurations that will cause inaccurate (out-of-square) prints.
I agree, but also disagree. I didn't have a power outage in years. Far less likely to have one during a print. I really don't need the printer to bang even the "correct" amount of times.
Just run the print head against the side once, then against the front, done. Maybe 2x to be sure. Bang bang, wrrrrr, bang bang, start printing.
But this "babb bubb babb bubb babb bubb babb bubb" still gives me a feeling of having bought a broken piece of crap, even after multiple projects and knowing what it's doing and why.
I have no idea why there wasn't an intervention when presenting the prototypes to give the customers a setting for this.
RE: Printing head calibration going wild
I loosened all the screws of the frame and then re-tighened them again. After that the alignment of the gantry was perfect.Now the printhead still hammers a few times, but it is way shorter now (only about 10 seconds).
Obvisouly the frame was not aligned in a 100% perfect right angle. I had tightened them during the built before the side plates and covers.Now with the covers and side plates the angles seem to correct themselves if you loosen the screws a bit.
This does not make sense to me. How can the enclosure profiles affect the geometry of the CoreXY mechanism?
The CoreXY is a self-contained unit, supported by its single-piece, laser-cut frame. That frame is "suspended" in the enclosure. I don't think that mounting the CoreyXY frame to the enclosure can actually distort that frame -- and especially that it can shear the frame in a way where the X vs. Y axes are not orthogonal in the XY plane.
RE: Printing head calibration going wild
The homing design isn't sloppy, but the design is quite sensitive to misconfigurations that will cause inaccurate (out-of-square) prints.
Just run the print head against the side once, then against the front, done. Maybe 2x to be sure. Bang bang, wrrrrr, bang bang, start printing.
But this "babb bubb babb bubb babb bubb babb bubb" still gives me a feeling of having bought a broken piece of crap, even after multiple projects and knowing what it's doing and why.
I agree with every words. This head banging is sloppy, especially when it's done for a feature I don't care about. Once X bang and one Y bang are all that I need.
The firmware itself is also sloppy, banging the head for more than minute without giving any indication on the screen of some progress or wether it's normal or not (it's not).
Prusa management needs to step in.
RE: Printing head calibration going wild
Also agreeing somewhat while somewhat disagreeing.
The printer has no idea where things are when it powers up, as someone could have moved the extruder around while powered off (or even without).
So, calibration is needed so it has some idea where things are. However, it homes in cases that make zero sense. Why thump-thump just because I inserted filament? Or removed it? Prusa has the ability to stop doing that when it's not needed.
Hmm. Perhaps it's time for me to dig into the firmware and issue a pull request with a patch?