Skipped layers / under extrusion & Extruder cover falling off

[BrickBoat]

Apololgies for long post but I wanted to be thorough.

I am experiencing two issues with my new (500 hours) P1S (that I will call my primary P1S)

1. Issue 1: Under extrustion / Missed layers (See exhibit 1) - this happens while running through the AMS and direct feed. It also occurs when using different materials. However, it does not occur on all models on my primary P1S. It does not occur on my secondary P1S
2. Issue 2: Extruder cover (i.e., front housing assembly) falling off during print (see exhibit 2) - this is a rare occurrence but has happened on multiple occasions.

Below I will summarise the diagnostics I have performed and then provide detail on the steps followed.

For reference, here are the materials that I have used in my testing and will refer to below

• Material 1: Bambu labs PLA Red
• Material 2: Bambu labs PLA Orange
• Material 3: Prima Value PLA+ Gray

Exhibit 1 A: Under extrusion / skipped layers - occur at a similar height on this model but not at exactly the same height

Exhibit 1 B: Same model and issue after some printer maintenance and calibration

Exhibit 2: Video of extruder cover falling off when trying to print the vase model. Has happened with other models but I didn’t get it on video
Primary P1S using first material and no AMS

Anyone else experience this? Any clue how to resolve?

Summary of diagnostics
I went through all the basic maintenance for my primary P1S before testing different materials and printing without the AMS. I also tried replicating issue 1 on my secondary P1S.

I believe this is a mechanical problem (I.e., not software) since the issue only occurs on the primary P1S and occurs with different materials and models.

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Detailed steps taken

Slicer settings: standard profile for PLA that comes with Bambi studio (0.2mm layer, 0.4mm nozzle)

I have tried the following steps to try resolve the issue

1. Performed basic maintenance on primary P1S (Tightened all screws, cleaned and greased y-axis rods, gresead lead screws, cleaned x-axis carbon rods): I got the same result as seen in exhibit 1
2. Factory reset and updated firmware primary P1S
3. Replaced the hot-end on primary P1S (in case there was a clog or the hot-end was bent). I got the same result as seen in exhibit 1
4. Printed the same model with a different spool (material 2) on primary P1S (in case it was a material issue): Same output as exhibit 1 (orange material)
5. Printed a tall / thin model to test z-axis shift on primary P1S: Switched back to material 1 for this test. this test was successful (see Exhibit 3) - I used my primary P1S and material 1
6. Printed without my AMS on primary P1S (in case the AMS had an issue or PTFE tubes were choking the filament): I got the same result as seen in exhibit 1
7. Retensioned the xy-axis idler pulleys on primary P1S (in case these were loose and causing the printer to lose track of it’s position in the xy-plane): I got the same result as seen in exhibit 1
8. Retensioned the z-axs timing belt on primary P1S: I got the same result as seen in exhibit 1
9. Printed the same model on my secondary P1S with material 1: print was successful
10. Printed the same model on my secondary P1S with material 3: Print came out as expected (see exhibit 4)
11. Printed vase model on my primary P1S (it’s less forgiving of z-axis shift and faster to print): Extruder cover fell off at around the same height as the failed print in test 9 (see exhibit 2)
12. Retried printing the vase model in material 3 on my primary P1S (to test if I could replicate the door falling off and to test if the material may be an issue): Print was successful (see exhibit 5) - this is confusing because test 4 (using material 2) eliminated material as an issue

Exhibit 3: Test print for z-axis shift - no failure in the print
Primary P1S using material 1 and no AMS

Exhibit 4: Model printed successfuly on my 2nd P1S
Secondary P1S using material 3 and my secondary AMS

Exhibit 5: Vase model printing successfully on my 2nd P1S

[RocketSled]

It looks like delamination more than that the layers were skipped, since there are areas where there is little or no “missing” material at the same layer height where there are gaps in other areas.

The print is warping as it cools. Bad layer adhesion causes it to separate unevenly, at the weakest point, producing those irregularly spaced gaps in the outer shell.

At a guess, this P1S extruder temp is being “over-reported”, the extruder is colder than it thinks it is… try doing a temp tower calibration with this printer and the one that works, that’ll tell you if the problematic machine needs a higher temp setting to extrude equivalently to the machine that works fine. Temp sensors can go bad. Or just bump the temp up by 20ºC or so and see if that fixes the problem.

[simon14]

From the video, it is likely faulty SD card.

The print head stops for a second because of the printer cannot read the next gcode from SD card, then it reads corrupted coordinate values and move to an absurd coordinate and crash the print head.

[BrickBoat]

Good point. I will try this in the morning

[BrickBoat]

The prints all happened via WiFi so this will not be the issue. Thank you for trying to help me solve issue #2

[simon14]

wifi/cloud is only for transfering the gcode file to the TF card on the printer.

Anyway, good luck.

[johnfcooley]

As @simon14 said, it’s the card.
The file is transferred via wifi once, stored on the card to “stream” if you will as it prints.

Doubt this? Take out the card and try to print something.

Your card is bad.

[BrickBoat]

Ah ok. I wasnt aware. I will test this today. Thanks for the tip.

[BrickBoat]

Thanks for the advice. I tested another card and it worked fine.

[BrickBoat]

We had the same issue at a higher temperature so we tried a new memory card. The card seemed to be the issue. Thanks for the help.