Since the latest firmware was installed, when I send a print job to the printer, it skips teeth or something before homing. It definitely looks like it is trying to move on the y axis beyond its bounds and makes an awful grinding sound. It recovers quickly (btw 1-2sec), homes, then runs fine.
this can also happen if the z axis is to low. starting gcode has the bed lower before starting. if the bed is to low need to move it up some.
as for the other axis i would just run a calibration to get the printer back on track
Is it hitting the boundary and grinding because it’s hitting the edge or is it grinding, then moving to the boundary? It sounds like the Y axis sensor isn’t stopping the head when it reaches the border. I’m with Akimbo, run a calibration.
Happens to me sometimes after powering it up and starting a print. Once it is powered on and homed, it never happens anymore, even after doing multiple prints.
This should def be looked into and make more bulletproof. Wondering how many times this can happen before hardware issues appear.
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Yeah, I’m honestly not really sure. It sometimes happens before a print and sometimes not. I need to watch more closely to see if I can tell where it is trying to move. At first blush, it appears to be attempting to move the y axis toward the back of the unit, but it is already all the way back there. I’m going to run another calibration on the unit as the other user suggested.
I don’t think it is a huge deal, it recovers very quickly and generally immediately homes afterward as part of the normal procedure anyway.
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It grinds first for few sec then it recovers in 1-2 sec and moves fine. It could be either Y or Z axis, I remember the head was somewhere in the middle of X, so it cannot be X.
I am not turning it off anymore to prevent this from happening.
Same here, I’ve noticed this issue after a month since I got the machine. Now, every time I power it up and whatever its first move is, self-test/ home/ start printing/ or calibrate, I will hear this grinding sound and then it’s fine. Feels like the sound is from the xy rods. Worried that it will potentially damage some parts.
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Today after powering it up, I homed it first and it did not make grinding sound since (even after several prints).
Does it grind for you if your first action after powering it up is home as well?
It just happened to me when bed was at the lowest position - it was clearly on Z axis - I could see the bed trying to go lower, but of course, could not. Is here anyone from Bambu monitoring this thread? It def looks like a serious issue.
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FWIW, this has been a known issue for some time now.
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Is there any solution for now? Perhaps making sure that the bed is not at its lowest position before initiating new print?
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Yes, that is the only workaround I’ve seen mentioned so far.
Maybe the reason why this happens is in machine G start code:
;===== machine: X1 =========================
;===== date: 20230130 =====================
;===== reset machine status =================
G91
M17 Z0.4 ; lower the z-motor current
G0 Z12 F300 ; lower the hotbed , to prevent the nozzle is below the hotbed
G0 Z-6;
G90
...
G91 sets to “relative” mode, which then follows by G0 Z12. If bed is already at lowest… then disaster follows.
EDIT: If my speculations are correct, then following modification should fix it:
;===== machine: X1 =========================
;===== date: 20230130 =====================
;===== reset machine status =================
;=== added by djeZo888 ======
G90
M17 Z0.4 ; lower the z-motor current
G0 Z30 F300
;=== end added by djeZo888 ===
G91
;M17 Z0.4 ; lower the z-motor current
G0 Z12 F300 ; lower the hotbed , to prevent the nozzle is below the hotbed
G0 Z-6;
G90
EDIT2: Not sure what would happen if you run this after power up, because printer doesn’t know location of Z at that time.
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I can confirm that this isn’t only happening on the z-axis. Issue also occurs on the y-axis randomly at the start of some prints.
Does it happen at the beginning? If you tell me at which point after start of the print it happens, I may find the problem in G code.
The solution I posted works for Y axis.
I did some further search and it looks like this is a problem that has been around since long time and nobody care to fix it. Like some people said, this G code is a mess and there are a lot of unnecessary moves and actions that could be removed thus reducing “preparation” time.
A few days ago, I’ve been printing Hydra AMS, which is fairly high and in subsequent prints I’ve experienced this issue as well.
Has BambuLab been notified about this bug?
Do they have bug tracker for firmware issues? Is it public?
Do we know when next firmware/Bambu Studio update is planned for release?
The issue happens when starting new print, after previous print moved bed to lowest position and printer has been turned off between prints. For me, workaround is simple: perform manual homing after turning the printer on.
djeZo888 > Do you know why Bambu has added lowering bed to startup gcode? Looks to me like some debugging code which unfortunately has been distributed to customers. During normal usage of Bambu X1C, nozzle should never get below hotbed.
No idea why this is there… it is useless. Perhaps it is there to solve issue in case of some rare combination of positions which would end up in failed print.
Btw, the G code I added seems like solves the issue plus it also works okay directly after printer is turned on. Since I have been using it, I do not get grindings anymore.
Furthermore I also changed end G code, so it does not drop the bed very low after print is finished. It is another possibility how to solve this issue.
...
M17 Z0.4 ; lower z motor current to reduce impact if there is something in the bottom
{if (max_layer_z + 100.0) < 225}
G1 Z{max_layer_z + 100.0} F600
G1 Z{max_layer_z +98.0}
{else}
G1 Z225 F600
G1 Z223
{endif}
M400 P100
M17 R ; restore z current
G90
G1 X128 Y225 F3600
...
So, instead of moving to 250 (or 248), I move it to 225 (or 223), which is 25 less. That is enough so that next time when print is initiated, bed wouldn’t go so low to crash anymore. But in this case, you still need to be careful to raise your bed a bit if you are doing manual bed adjustments dropping it down to the very low/lowest position.
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I haven’t been printing as much throughout the past couple days, and I don’t consistently run into this issue. The things I’ve been printing have not been tall, so I am starting to think that perhaps I was just overlooking how low the bed actually was when I was beginning the prints I was hearing the grinding on. Since I haven’t had the issue in a few days, I’m starting to doubt my previous claims that this was happening on the Y axis too. Still keeping an eye out though, will capture some detail or a video if it happens again.
Actually, the print doesn’t have to be very tall, the code shows that the bed will drop down if the object is 150mm or taller.
This is normal if your bed is all the way lowered. Naturally it wants to move the bed down a little on startup to make sure it is out of the way of the print head moving. If you’re concerned, make sure the bed isn’t bottomed out before you power off the printer, then it won’t do that at startup
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