Nozzle keeps diving into the buildplate

Hey guys, I'm getting a bit desperate now.

My V-Core300 has started by hitting printed parts mid print and most recently it lays the first couple of layers and simply dives into the build plate.

I've done the following since the problem started to try and fix it with no success:

Upgraded from 3.0 to 3.1
Reinstalled RatOS and reconfigured everything step by step
Checked all the Z motors wiring, re crimped everything

I have a ruined buildplate and nozzle now and I cannot seem to find the issue.

Any ideas?

abcurrie•12/26/22, 3:33 PM

Check the couplers on the stepper motors and the lead screws. Not sure if you are using the new couplers or not. In the past I had one coupler that no matter how tight I set the screw the connections still was not secure. Had to replace the coupler

hurt-tomatoOP•12/26/22, 3:34 PM

Couplers are new, replaced the old design couples with the new ones when upgrading to 3.1

abcurrie•12/26/22, 3:38 PM

Just because the are new doesn't mean that they are working or not slipping. It is very difficult to assess if the connection to the stepper motor shaft is slipping. I would try running the bed up and down while gripping the lead screw with your hand as tightly as possible.

abcurrie•12/26/22, 3:39 PM

When you are running into the bed is that after the print and starting something new? If so, points to a mechanical mismatch between where the printer thinks the bed is at to where it actually is

hurt-tomatoOP•12/26/22, 3:43 PM

It's random. It either dives into the bed doing the prime line or after 3 or 4 successful layers.

abcurrie•12/26/22, 3:46 PM

Are you using Z-hop while printing? If there is a lot of bed movement during a layer print and there is slipping, the effect is cumulative.

hurt-tomatoOP•12/26/22, 3:47 PM

I am. But it also does it before starting the first layer so don't think that could be the issue.

abcurrie•12/26/22, 3:51 PM

One other symptom I had was multiple tries to get the bed level when doing a z-tilt adjustment. Any issues there?

hurt-tomatoOP•12/26/22, 3:52 PM

Nope. Tilt adjustment works like a charm. I've ran the Z tilt adjustment, ran the bed on the Z axis multiple times up and down, repeated z-tilt adjustment and it was bang on

abcurrie•12/26/22, 3:53 PM

Any sign of stepper motor skip?

hurt-tomatoOP•12/26/22, 3:54 PM

No signs of skipping

abcurrie•12/26/22, 4:01 PM

puzzling. I would not suspect software as sometimes it works and sometimes it does not. When it happens after 3-4 layers indicates that the Z offset is correct. This points to electrical or mechanical problems, not software.

abcurrie•12/26/22, 4:02 PM

This only started after the 3.1 upgrade? It was working fine before?

hurt-tomatoOP•12/26/22, 4:04 PM

Tell me about it! It's been an issue for a long time now. Well before the 3.1 upgrade. I've taken it apart and rebuilt it / checked everything over dozens of times

I'm really at a loss here.

abcurrie•12/26/22, 4:17 PM

That's interesting... So the issue is not new but has been there for a while. The fact that it is intermittent still points to electrical or mechanical, not software. Hitting things on the bed when printing and crashing the nozzle into the bed indicates a mismatch between physical nozzle height and calculated nozzle height. When this happens and you start the print bed leveling all over again, is there one bed screw that seems to be higher than the others? This would at least indicate one axis fault rather than all three

hurt-tomatoOP•12/26/22, 4:20 PM

No, nothing obvious. I've been chasing the problem for a while now and replaced pretty much everything i could think of that could influence this issue. At some instances the probe offset would be quite off after a crash, but other times it was spot on.

abcurrie•12/26/22, 4:27 PM

Trying to understand what you said about the probe offset. This usually does not change much once set up. Bltouch or Inductive?

hurt-tomatoOP•12/26/22, 4:28 PM

inductive probe. It shouldn't no.

abcurrie•12/26/22, 4:28 PM

The numbers I am talking about are related to the Z-tilt. After a problem and you do a z-tilt is one axis need much more adjustment than the others?

abcurrie•12/26/22, 4:28 PM

11:26 AM
Retries: 1/10 Probed points range: 0.018125 tolerance: 0.020000
11:26 AM
Making the following Z adjustments:
stepper_z = 0.020580
stepper_z1 = -0.001633
stepper_z2 = 0.002258
11:26 AM
probe at 360.000,60.000 is z=4.053828
11:26 AM
probe at 235.000,370.000 is z=4.049453
11:26 AM
probe at 60.000,60.000 is z=4.067578
11:26 AM
Retries: 0/10 Probed points range: 0.041563 tolerance: 0.020000
11:26 AM
Making the following Z adjustments:
stepper_z = 0.163051
stepper_z1 = 0.111797
stepper_z2 = 0.126393
11:26 AM
probe at 360.000,60.000 is z=4.178750
11:26 AM
probe at 235.000,370.000 is z=4.164687
11:26 AM
probe at 60.000,60.000 is z=4.206250
11:26 AM
Z_TILT_ADJUST

Aaccused-moccasin The numbers I am talking about are related to the Z-tilt. After a problem and y...

hurt-tomatoOP•12/26/22, 4:28 PM

Ahh no, they remain spot on

abcurrie•12/26/22, 4:29 PM

printout just done on mine. Is one stepper motor always needing more adjustment than the others?

hurt-tomatoOP•12/26/22, 4:29 PM

No, they're all very consistent

abcurrie•12/26/22, 4:36 PM

So all three stepper motors have very close and similar numbers?

abcurrie•12/26/22, 4:36 PM

stepper_z = 0.163051
stepper_z1 = 0.111797
stepper_z2 = 0.126393

abcurrie•12/26/22, 4:36 PM

But sometimes that Z-probe offset is right on and at other times it is off? By how much?

abcurrie•12/26/22, 4:39 PM

my numbers just shown are higher than normal because it was done on a cold bed just to capture some numbers

hurt-tomatoOP•12/26/22, 4:42 PM

The Z-probe offset sometimes drifted by 4 or 5mm. Which doesn't make any sense. It hasn't happened since the last major rebuild.

hurt-tomatoOP•12/26/22, 4:44 PM

stepper_z = 0.052376
stepper_z1 = 0.086585
stepper_z2 = 0.096440

hurt-tomatoOP•12/26/22, 4:44 PM

straight after last crash...

abcurrie•12/26/22, 4:44 PM

That is huge! Are you doing a bed mesh before each print?

hurt-tomatoOP•12/26/22, 4:45 PM

i am. but that issue hasn't happened since i rebuilt it

abcurrie•12/26/22, 4:51 PM

so to recap, after the rebuild, z-probe offset consistent. Z-tilt adjustment small and similar for all steppers. Bed crash sometimes on prime line, sometimes after a few layers. No signs of stepper motor skip. no signs of mechanical slipping.

hurt-tomatoOP•12/26/22, 4:55 PM

Yep, that pretty much sums it

abcurrie•12/26/22, 5:00 PM

Argh! Can you post your printer.cfg file to see if anything stands out?

hurt-tomatoOP•12/26/22, 5:06 PM

Of course.

printer.cfg13.83KB

abcurrie•12/26/22, 5:39 PM

I admit that I am not an expert on the printer.cfg, but I don't see any outstanding issues. Very few custom options. I see that you have configured the performance items that should speed up motors and use more current. A long shot but possibly try the generic options??? Really struggling to find more things to try, as have you I am sure....

hurt-tomatoOP•12/26/22, 5:41 PM

I had quite a .cfg file that had a lot of customization but i've decided to start from scratch to ensure I wasn't inducing the problem. I've tried the standard non-performance configuration as well. Same outcome

Rrlopes The Z-probe offset sometimes drifted by 4 or 5mm. Which doesn't make any sense. ...

sherbs•12/26/22, 10:12 PM

What do you mean z-probe offset drifted by 4-5mm?

hurt-tomatoOP•12/26/22, 10:40 PM

After running into the bed, I’d do the z probe. Calibrate and it would move quite a lot. Never understood why - the print head is rock solid. But that problem seems to be gone since I last reassembled everything

Ouchmaster•12/27/22, 5:43 PM

lower your plate by 30 cm and raise it up by 30cm, do that twice. probe before and then after and advise if nozzle distance from build plate increase or decrease significantly

hurt-tomatoOP•12/28/22, 12:04 AM

Done that and the readings are very consistent and works as it should. I've swapped the motor drivers and the problem persists, however I've spotted something today for the first time. Whilst doing the primeblob, in the blob extrusion phase (sationary X and Y), the right Z motor was ticking upwards. I'm pretty sure that is the problem, just need to find out where it comes from. At this point it's either the motor or the controller board. I'm going to have a second check at the wires themselves but... doesn't really seem they could be the issue.