Stop head banging with GCode......
So used the revised Prusa directions to tune the belts. Both tuned to new values but it's made my head banging, which was very low previously, a lot worse - taking a minute or two of head banging between prints.
I recall reading this was for accurate resume after a printer or power failure etc - I do not need this.
Im sure I read somewhere some code could be added after the G28 in the start GCode section to stop head banging, but I can't find where this is. Could someone please enlighten me?
If I place this in the start GCode once, will it remain for all future models I slice and upload to my printer, or does it need to be added every time?
RE: Stop head banging with GCode......
In prusa slicer in the Start G-Code for my printer I have:
G28 I ; home all without mesh bed level
RE: Stop head banging with GCode......
Normally signifies the gantry isn't square mate. Id check that before disabling anything.
RE: Stop head banging with GCode......
Tried everything.
Gantry is completely square. Belts are tuned to the newly recommended values, etc - everything looks good.
I was fine with the older 85hz belt values TBH - 2 head bangs each time and that was it. If my gantry wasn't square I'd assume I would have problems then too. All I have done is tighten up my belts to the newer values in order to get rid of some of the noise while printing - where it seems to have helped a little, although not completely. Since doing this the head banging is back. Rather then go back to looser belts I'm happy to just add the GCode - very rarely have any power outages, and I don't use the Core One for longer prints anyways - I have another printer that is outside in my outbuilding (with full remote operation and cameras etc) that I can leave running for long prints without having any noise overnight in the house!
Normally signifies the gantry isn't square mate. Id check that before disabling anything.
RE:
Tried everything.
Gantry is completely square. Belts are tuned to the newly recommended values, etc - everything looks good.
I was fine with the older 85hz belt values TBH - 2 head bangs each time and that was it. If my gantry wasn't square I'd assume I would have problems then too. All I have done is tighten up my belts to the newer values in order to get rid of some of the noise while printing - where it seems to have helped a little, although not completely. Since doing this the head banging is back. Rather then go back to looser belts I'm happy to just add the GCode - very rarely have any power outages, and I don't use the Core One for longer prints anyways - I have another printer that is outside in my outbuilding (with full remote operation and cameras etc) that I can leave running for long prints without having any noise overnight in the house!
Normally signifies the gantry isn't square mate. Id check that before disabling anything.
If you were fine with the old tuning, then why not go back to it? I haven't really noticed (in my case) any difference in VFAs one way or the other. I too would avoid a g-code patch since that may just be masking any issues with gantry geometry. I suppose it goes back to the maxim: "If it isn't broken, don't fix it"
RE: Stop head banging with GCode......
I suppose it goes back to the maxim: "If it isn't broken, don't fix it"
Even if everything is perfect, the 'G28 I' will reduce the head bangs at the beginning of the print from 12 to 4.
RE: Stop head banging with GCode......
Double check your gantry. It simply is not square if it bangs more than 4 times...
RE: Stop head banging with GCode......
I suppose it goes back to the maxim: "If it isn't broken, don't fix it"
Even if everything is perfect, the 'G28 I' will reduce the head bangs at the beginning of the print from 12 to 4.
I'm not injecting this g-code I have only 3 head bangs. It was a lot more until I correctly tuned the belts and re-squared the gantry. I would recommend starting with that and if it doesn't help, then use the g-code.
RE: Stop head banging with GCode......
I have only 3 head bangs.
Are you sure? I have never seen less than the 12 bangs @zapta mentioned, neither on my own printer nor in any videos from others:
"Left, left, front, front -- left, front, left, front, left, front, left, front."
RE: Stop head banging with GCode......
Umm, make that "right, front" etc. Apparently I can't tell left from right anymore... but I am confident enough about front vs. back! 😉
I have only 3 head bangs.
Are you sure? I have never seen less than the 12 bangs @zapta mentioned, neither on my own printer nor in any videos from others:
"Left, left, front, front -- left, front, left, front, left, front, left, front."
RE: Stop head banging with GCode......
Umm, make that "right, front" etc. Apparently I can't tell left from right anymore... but I am confident enough about front vs. back! 😉
I have only 3 head bangs.
Are you sure? I have never seen less than the 12 bangs @zapta mentioned, neither on my own printer nor in any videos from others:
"Left, left, front, front -- left, front, left, front, left, front, left, front."
I'm 8500km away from my printer right now. But I remember there being 3 "groups" of head bangs. I'm not differentiating between X and Y. As opposed to taking several minutes before properly tuning the belts and squaring the gantry
RE:
I just want to make sure that we don't establish false expectations what an optimum number of head bangs can be. We don't want readers to fiddle with gantry squaring and belt tension forever, in search of those elusive "only three bangs". If you count individual bangs into the end stops, I think 12 is the optimum with the current firmware (and the "precision homing" triggered by the regular G28 command).
RE: Stop head banging with GCode......
I just want to make sure that we don't establish false expectations what an optimum number of head bangs can be. We don't want readers to fiddle with gantry squaring and belt tension forever, in search of those elusive "only three bangs". If you count individual bangs into the end stops, I think 12 is the optimum with the current firmware (and the "precision homing" triggered by the regular G28 command).
Yeah 12 is where I'm at, and it's never been less than that, and like you I have never even seen less than that. Gantry is perfect square and belts are at 98/92.
After powering on I normally use the 'Auto Home' menu option, which I presume is G28..'home all axis'.
RE: Stop head banging with GCode......
I just adjust the belts slightly to pull the right side in slightly and it goes away, the difference between it calibrating all day long and just be done with a few bangs can be tiny. I found the new belt tension worse than the old, or even very sloppy belts, had very little VFA to start with so i went back 🙂
RE: Stop head banging with GCode......
I remember there being 3 "groups" of head bangs.
Yes, 3 groups, 2 + 2 + 8 bangs. If you use 'G28 I' you will get only the 2 + 2.
RE: Stop head banging with GCode......
My CORE One Kit printer does the same - excessive head banging every time it starts the print. Many times it prints an error screen notifying me that the print head is blocked, then continues with printing and the print itself is flawless afterwards (even with the error screen).This looks to me as a software issue, not a hardware issue caused by a supposedly incorrect calibration.Does anybody know what the software tries to do by repeatedly banging the printer head? Can it not detect the head has reached its axis limit (bang happened) on the first attempt and the adjust its origin in software? I understand it needs to do it (reach the axis limit) probably twice to verify that the origin/limit has really been reached - but to do it 12 times possibly damaging the printer itself looks to me as a software bug. I might be wrong though, as I do not know what the software really does when it bangs the printer head - it could do an accelerometer calibration/verification perhaps (during the bang the accelerometer must report some excessive values). Possibly the subsequent bangs should not be done with such high velocity, but verify the origin by slowly moving the print head instead, to prevent printer damage. I'll use the Gcode fix for now.
RE: Stop head banging with GCode......
> Does anybody know what the software tries to do by repeatedly banging the printer head?
Here is a summary
1. Prusa didn't install end limit sensors to reduce the production cost of the Core One.
2. The sensorless end limit detection works and provides a resolution of a 1 full stepper motor step.
3. Prusa wanted to have a better resolution and invented an algorithm for refining the resolution using additional diagonal head bangs.
4. The altorithm is brain dead and can bang the head for hundreds of time before stopping.
5. Prusa refuses to remove that algorithm or allow users for disable it.
In summary, a the fix is easy and trival but Prusa refuses to admit that their algorithm causes for damage than good.
RE: Stop head banging with GCode......
It's statistics applied to a bouncing ball. The belts stretch (minutely, but stretch they do). Driving the gantry to the stops multiple times allows averaging, or in layman's terms: a better guess at reality. Same reason behind multiple taps with the proximity detector/load cell to find nozzle distance to sheet.
RE:
If your head bangs more than 12 times in total, (4, then 4 x2) either your gantry isn’t square or your tensions are off. It’s that simple.
I don’t think that’s excessive, and last time I set mine, must’ve been over a month ago….and that was only because I wanted to change out a tensioner housing and lubricate the tensioner screws.
Im far from a Prusa apologist, but I really don’t have a problem with this pre print calibration it does.