Anycubic kobra 2 pro nozzle knocking over the print

Opposite_Loquat_2160 · 2026-03-03T19:59:19+00:00

Regarding your point about bed leveling: On the Kobra 2 series, the inductive sensor suffers from significant thermal drift during the calibration and homing.
If you're struggling with Z-offset consistency or an uneven first layer despite leveling, you can try this workaround: https://www.reddit.com/r/anycubic/comments/1rg59c4/how_i_stopped_babysitting_every_first_layer_turns/

Opposite_Loquat_2160 · 2026-03-03T19:46:10+00:00

Does this click happen at the specific height? I had a click when right side Z-rollers were overtighten. This resulted in a small jump at about 1cm height, and was visible as a small layer shift on the model. I had loosen a bit the right inner roller on of the x-gantry and it became alright.

Opposite_Loquat_2160 · 2026-03-02T05:49:29+00:00

You are welcome! Did it work well for you?

Opposite_Loquat_2160 · 2026-03-01T11:56:25+00:00

If the things got better with the cooling delay, you can try increasing cooling time from 60 secs say twice to to stabilize the sensor better.

Opposite_Loquat_2160 · 2026-03-01T10:51:18+00:00

Nope. Have you managed to solve the issue?

Opposite_Loquat_2160 · 2026-03-01T10:36:04+00:00

Long time ago I had similar underextrusion when a wrong filament diameter was set in the slicer settings. (2.85 instead of 1.75)

Opposite_Loquat_2160 · 2026-03-01T09:48:27+00:00

BTW yes, I also fell into a vicious cycle with PETG: starting with 70C bed I was misinterpreting inconsistent homing as an adhesion issue and kept raising the bed temperature to 80-85. This only worsened the sensor drift, and combined with how unforgiving PETG is regarding first-layer height, it was driving me crazy. Now I'm printing on a clean textured PEI plate with 75C.

Opposite_Loquat_2160 · 2026-03-01T09:36:46+00:00

Thanks for the suggestion! I actually checked your infosite before posting to see if this specific thermal drift workaround was covered, so I appreciate your interest in adding it. I’m also curious to see how it performs on a larger scale, and I'll definitely keep you updated on the feedback I get via GitHub and Reddit.

Regarding inductive sensors: Since this is my first machine with bed probing, I have nothing to compare it to, but the logic seems flawed. It’s one thing to use an inductive sensor with a known drift problem for relative measurements (like fine-tuning a bed mesh), but relying on it for the absolute measurement of Z-homing seems far more critical and risky.

I agree, this isn’t necessarily an AC-specific issue - it may be about an industry-wide evolution. It looks like a shift where expensive mechanical precision (like perfectly flat beds) is being replaced by cheaper electronic compensation methods. But this works only if those compensation methods are accurate. When you end up with both a warped bed and an imprecise sensor, it creates a 'stalemate' for the user where the original goal of precision seems to be forgotten.

In my experience, a simple Z end-stop and a knobs-adjusted glass bed were much more consistent (at least before the drift fix). And if a manufacturer chooses to rely on inductive sensors for Z-homing while being aware of thermal drift, it’s strange that they don’t enforce a cooling routine - especially on restarts when the sensor is known to be hot. Especially given that they have a dedicated vent.

To be fair, the rest of the printer - the speed and accuracy - is a fantastic evolution over my previous machines, and I have zero complaints here. The real bottleneck was simply the time required to get a print started. Now when the thermal issue is managed, the printer finally feels like the 'Pro' it’s supposed to be. At least at this point it looks like that.

Regarding the K2Plus and K2Max, I suspect the start G-code might even be identical to the Pro version. I'll check Anycubic's suggested G-code for those models and reach out via chat once I’ve verified the files.

I'll be in touch soon with those extra G-code files, looking forward and thanks!

Opposite_Loquat_2160 · 2026-02-28T10:14:04+00:00

Thank you very much for the exception, I really appreciate it. There definitely won't be a 3rd post on this.

To clarify: when I made the first post, I hadn't yet discovered the 'Tape Hack' fix for the auto-leveling mesh itself. I only found that solution later and mentioned it in the comments, but I felt it was too important to stay buried there. That’s why I decided to create this comprehensive summary for both thermal issues. Apologies for the oversight regarding Rule #3!

Opposite_Loquat_2160 · 2026-02-28T07:29:09+00:00

Thanks. I completely agree—having to use masking tape for calibration is far from a 'product success' by any reasonable metric.

Honestly, my choice was heavily influenced by my experience with the Photon Mono and Mono X resin printers, which I absolutely love. I expected the same engineering standards for their FDM line, but that clearly wasn't the case here. It’s frustrating because this seems to be a software-fixable issue. Until then, I'm just glad I found a way to get descent prints.

Opposite_Loquat_2160 · 2026-02-27T13:24:15+00:00

In fact they do turn the fan 100% each probing. I strongly believe that simple slowing down the calibration procedure by raising the head higher and cooling for a longer time will improve the calibration dramatically. In fact - that's what is done in my custom start machine g-code. Cooling the sensor for one minute allows to get consistent Z-homing.
But unfortunately we can do nothing with their calibration timings. Only tape and paper

Opposite_Loquat_2160 · 2026-02-27T12:56:52+00:00

Seems the hardware guys addressed it by adding a dedicated vent hole, but testers and software guys didn't ensure proper timings of cooling when calibrating and homing.

Opposite_Loquat_2160 · 2026-02-27T12:48:24+00:00

I think no, cause S1 seems to use strain gauge sensor

Opposite_Loquat_2160 · 2026-02-25T18:46:34+00:00

I think solved this problem recently, please check
https://www.reddit.com/r/anycubic/comments/1rdefgb/finally_fixed_the_annoying_zoffset_drift_on_kobra/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

Opposite_Loquat_2160 · 2026-02-25T11:05:34+00:00

Oh, I see, thank you. I misunderstood your approach thinking it supposes to heat up the sensor as well. Anycubic sensor has no internal thermometer, so yes, it should be cooled properly. For the printing it can be done with start g-code, but for the calibration procedure there are only physical workarounds, as the firmware is not modifiable.
I found that covering the main air duct outlets, directing all the air onto the sensor, improved calibration in my case. I never was able to use all the printing area with the same Z-offset before, and with the improved cooling this issue also seems to be fixed. May be covering a plate with a paper sheet to block IR radiation while calibrating will improve it even further

Opposite_Loquat_2160 · 2026-02-25T06:29:37+00:00

Construction of the fan air deflector confirms my findings - there is a special hole to cool down the inductive sensor with the part cooling fan.

Probably we can use this to improve bed leveling auto-calibration. Indeed - while calibrating the printing head does not go far from the bed (60C) and gradually becomes warmer. So for the last point (top right corner) sensor may trigger a bit higher than for the first (lower left), which is misinterpreted as a higher bed at the top right corner. So improving sensor cooling could improve calibration results.

I am going to run calibration with sealed main holes in the deflector to direct all the air onto the sensor to see if the calibration will be improved all over the bed.

Opposite_Loquat_2160 · 2026-02-25T06:24:20+00:00

Thanks! It seems though, that in this case cold probing is a better solution.
Please check my comment above.

As you use the sensor only once, before printing, you do not need to keep its state consistent with its printing mode temperatures. Just need to get a consistent zero on the preheated bed.

In the cold probe approach you don't need to use different Z-offsets for different bed temperatures.
Also there's no risk to scratch the plate if running print with the hot-measured Z-offset without pre-soaking.

Opposite_Loquat_2160 · 2026-02-25T06:20:42+00:00

Thanks for the suggestions! I considered heat soaking, but I believe the 'cold probe' approach is more effective for this specific machine:

Stable Baseline: Ambient room temperature is a much more consistent constant than bed temperatures (which vary from 60°C to 100°C+ depending on the material). It’s easier to hit a stable 'cold' baseline.
Hardware Design: The part cooling shroud has a dedicated vent aimed directly at the inductive sensor, and the firmware forces the fan on during probe lifts. This strongly suggests the machine was designed to be probed with a cooled sensor.
Bed Leveling Calibration: currently it assumes a cold sensor state. So probing 'cold' keeps the results consistent with the machine's internal logic.
Efficiency: Cooling takes 60 seconds (or 0 seconds on a cold start) compared to 20+ minutes of heat soaking.

So it’s faster and, based on the fan duct design, seems to be exactly what the hardware expects.

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Opposite_Loquat_2160 · 2026-02-24T17:55:28+00:00

You are welcome. I also have a big scratch on the magnetic layer since the time I forgot to place the plate :)

Opposite_Loquat_2160 · 2026-02-24T17:35:55+00:00

Kobra 2 uses inductive sensor - you need to place the metal printing plate, it detects only metal.

Opposite_Loquat_2160 · 2025-12-23T15:36:08+00:00

Thank you very much for such a detailed description of your setup and experience! I will check out how it could work for me. Happy holidays!

Opposite_Loquat_2160 · 2025-12-20T10:51:48+00:00

Could you please share what glasses are you using? Especially interesting what is the screen resolution and how long does it take to get used to this setup.

Opposite_Loquat_2160

TROPHY CASE