Anycubic Kobra 2: 26 Known Issues and How to Fix Them

The Anycubic Kobra 2 is a 2023 open-frame FDM printer with a 220×220×250 mm build volume, a 4:1 direct drive, a 260 °C hotend and a 110 °C bed. It's discontinued, but there are a lot of them still running. This guide covers the problems that are specific to this machine — from thermal drift in the auto-leveling probe to the proprietary nozzle that regular Volcano tips won't fit. Generic FDM issues live in their own guides, linked at the end.

1. Z-offset drifts between prints because the probe heats up

This is the number one complaint and the most confusing one: a cold printer lays a perfect first layer, but start a second print right after the first and the nozzle rides too high and prints in the air. You dial the offset down live, sometimes to −0.5 mm, and then the next cold start scrapes that same value straight into the plate.

It isn't mechanical. The inductive probe soaks up heat from the bed and the nozzle and starts triggering earlier, meaning higher. The hotter the probe, the bigger the nozzle-to-bed gap. The full analysis plus a ready-made fix lives in the anycubic-kobra-2-pro-thermal-drift-fix repo, which ships start G-code for the whole Kobra 2 family including the base model.

The fix is a "cold probe" routine: rough home, lift the head 100 mm away from the hot bed, run the part cooling fan at 100 % for a minute, and only then find Z zero. Here's the core of the start G-code — paste it into the machine start G-code field of your slicer (Anycubic Slicer Next, OrcaSlicer or PrusaSlicer).

2. Auto-leveling invents a warped bed that isn't there

The same heat soak wrecks the mesh itself. LeviQ 2.0 probes 25 points in a 5×5 grid, and the probe spends several minutes hovering over a hot bed while it works through them. It triggers progressively earlier, so the printer records the far corner as "higher" than it really is. You end up with a skewed mesh on a perfectly flat bed: squished on one side, printing in the air on the other.

1. Tape off the bottom part-cooling outlets so all the airflow goes through the shroud's built-in vent, which points straight at the probe.
2. Drop a sheet of white paper on the plate to cut radiant heat from the dark surface.
3. Run Auto-Leveling from the printer menu. The firmware fires the fan after every probe point, and with the outlets sealed the probe actually cools down.
4. Remove the tape, set your Z-offset and print test pads in all four corners plus the center.

3. "Leveling is abnormal": dust inside the offset switch

The Kobra 2 uses two separate sensors. The inductive probe on the head builds the mesh, and a spring-loaded 10 mm metal button sits on the bed at the rear left — it's just a switch the nozzle presses to find true zero. Dust builds up inside the housing, insulates the contacts on the little PCBs, and you get "Leveling is abnormal, please check whether the wiring of the calibration module or the X/Y coordinates are normal!" on screen.

1. Press the button by hand: it has to depress and pop back up on its own. If it sticks, back off the screws behind the module slightly with an M2.0 hex key.
2. Check the position: Prepare → Leveling → Module calibration → Position calibration. The nozzle must land dead center on the button; if it doesn't, nudge X/Y right there and save.
3. Reseat the module connectors at both ends — they ship loose more often than you'd think.
4. Still failing? Pull the PEI plate, unscrew the module behind the bed (M2.0 hex), pry the housing open (two small springs inside — hold it), take out both PCBs and wipe the contacts and metal pads with a lint-free cloth.
5. If you're comfortable with a multimeter: pin 4 of the module port on the mainboard should read 3.3 ± 0.3 V. No voltage means the board is the problem, not the sensor.

The full teardown with photos is in the official Anycubic Wiki maintenance guide for the offset module.

4. The offset button doesn't sit flush with the plate

The printer treats the top of that button as the print surface. If the pad sits above the plate, the nozzle ends up too high; if it sits below, the nozzle digs in. There's no error message — the Z-offset is just permanently wrong no matter how much you tweak it.

1. Lay something flat on the plate — the large open-end wrench from the toolkit works — so it overhangs the button.
2. Slide it across toward the sensor. Catches the button? Too high. Leaves a gap? Too low. It should just kiss it.
3. Holding the wrench down firmly, loosen the module's M2 side screw half a turn — the button self-levels — then retighten.
4. Confirm the button still travels freely and returns by itself.
5. Re-run auto-leveling: your old mesh is invalid after this.

5. Z-offset won't adjust after the 3.0.6 firmware

A separate story reported on r/AnycubicOfficial: after installing V3.0.6 the Z-offset adjustment stops taking effect and every calibration pass drops the nozzle lower, eventually gouging the plate finish. Module wiring, belt tension and screws all check out fine.

1. Reset the printer to factory defaults and run calibration again — that was enough for some owners.
2. Run the calibration on the smooth side of the steel plate instead of the textured PEI side. That's what finally fixed it for the original poster after everything else failed.
3. Grab the "PLA Profiles for V3.0.6" PrusaSlicer bundle from the official firmware page — the older profiles weren't built for this version.
4. If nothing helps, V2.9.3 is still posted on the same page and rolls back the same way, from the card.

6. The inductive probe isn't 2 mm above the nozzle

That orange probe tip on the head belongs roughly 2 mm above the nozzle tip. Set it higher and the probe never sees the steel plate, so the nozzle drives straight into the bed. Check it on a brand new printer and after every hotend teardown — the bracket is plastic and creeps under vibration.

No gauge? A sheet of paper and the big open-end wrench do the job: lower the head until the nozzle pinches the paper, then slide something flat and roughly 2 mm thick under the probe — the large open-end wrench works — and the probe should touch it. If it doesn't, loosen the bracket screw, slide the probe, retighten and re-run calibration.

7. The Z-axis timing belt ships loose from the factory

The Kobra 2 runs two T8×8 lead screws joined at the top by a closed-loop GT2 belt, 6 mm wide and 600 mm long. The motor drives one screw and the belt drags the other along. On basically every machine in this family that belt arrives slack — you can push it aside with a cotton swab using no force at all. The result is a driven-by-belt side that lags behind and layer height that wanders.

1. Measure the distance between the screws at the bottom, just above the coupler and bottom bearing (expect roughly 274 mm).
2. Measure the same distance at the top. Typically it's about 2 mm less.
3. Measure each screw to the frame rail at the bottom and top to work out which one is leaning.
4. Loosen the two screws of the offending top bearing block, pull it into position, hold and retighten.
5. Measure again: top and bottom should match, and the belt tensions itself.
6. While you're up there, add M3 screws to the top bearing blocks — Anycubic leaves them out and the bearing is held by press fit alone.

8. A tilted bed thanks to four uneven spacers

The Kobra 2 bed bolts to the Y carriage through four rigid metal spacers — no springs, no adjustment screws anywhere. Which means "auto bed leveling" levels nothing physically: it measures 25 points and compensates in software by moving Z. If the spacers aren't the same height, the bed starts out tilted and compensation runs out of road on big deviations.

1. Take the bed off the carriage and pull the four spacers.
2. Measure them with calipers, or just stand them side by side on a flat surface.
3. If they differ, sand the taller ones down to match the shortest, keeping each one dead vertical against the sandpaper.
4. Alternative used by Kobra 2 Plus owners with the same defect: shim the short spacers with 0.2–1 mm washers.
5. Reassemble, tram the X gantry to the bed, then re-run auto-leveling.

9. The right side of the X gantry sags

The X gantry rides the Z frame on POM wheels, three per side. The catch: only the inner wheel has an eccentric nut, so the third wheel often hangs in mid-air and you can rock the unsupported right end of the gantry by hand. On prints that shows up as different layer heights left versus right, plus waves on the walls.

Twisting that one eccentric nut won't fix it — it only moves its own wheel. You need to loosen the Y-shaped brackets the wheels mount to, set them so all three wheels sit in the extrusion slot, then retighten. Finish with the eccentric nut: wheels should roll freely with no play.

10. POM wheels shedding flakes

Fine dust off the wheels is normal — it's a soft polymer. Flakes after a couple of spools are not. That means the eccentrics are cranked too tight and the wheels are running with interference, or they're misaligned. Back the preload off, verify each wheel tracks squarely in the slot, and inspect for grooves: a chewed-up wheel doesn't recover.

11. Play in the head and bed: the SG15 bearings

X and Y on the Kobra 2 don't use POM wheels — they run U-groove SG15 metal bearings on round steel rails. On X only one of the three bearings is adjustable: the bottom one with the eccentric nut. The two on top are fixed. So when the head wobbles, that bottom bearing is your only lever.

Don't overtighten. Metal on metal under preload eats both the bearing and the rail — owners have reported visible rail wear after a single spool. Wipe the rails and bearings monthly and put a thin film of grease on them. Anycubic's own schedule for the rails and lead screw is on the Maintenance Recommendations page.

12. The PTFE inliner cooks and the clogs begin

This hotend isn't all-metal: a roughly 41 mm PTFE tube runs down the heatbreak all the way to the nozzle. Fine for PLA, except the printer lets you set 260 °C while PTFE starts breaking down around 250 °C. Run it hot for long enough and the tube browns, deforms and narrows the bore — filament stops feeding and the extruder starts clicking.

1. Pull the head cover (mind the part cooling fan wire) and unplug T0 and H at the breakout board.
2. Loosen the two grub screws in the middle of the heatsink — the whole hotend drops out, so hold it.
3. Pull the inliner. If it fights you or won't budge, it's already deformed; heat the hotend and pull it out hot.
4. Inspect the bottom end: brown discoloration, melting or a squashed tip means replace. Capricorn XS handles more heat than the stock tube.
5. Cut the new tube perfectly square and push it until it bottoms out against the nozzle — any gap collects plastic that burns and drops dark specks into your prints.
6. For PETG and other hot materials keep the ceiling below 250 °C, or fit a bimetal heatbreak and reduce your retraction distance.

13. The nozzle is proprietary: real Volcano tips won't fit

The heater block looks Volcano-shaped, which trips people up: they buy standard long Volcano nozzles and nothing seats correctly. The stock heatbreak has a cylindrical recess machined to accept the matching feature on the stock nozzle — a classic Volcano tip never mates flush with it, and molten plastic escapes through the joint.

Two options: buy nozzles sold specifically for the Kobra 2 series, or swap heatbreak and nozzle as a pair — bimetal heatbreaks marketed for the Anycubic Vyper fit (M6 thread, 6 mm throat, 26 mm overall) and take true Volcano nozzles. For abrasives like carbon fiber you want hardened steel; brass wears out fast on abrasives.

14. A blob on the heater block and a heater that falls out

If the nozzle and heatbreak aren't clamped tight against each other inside the block, melt squeezes out of the joint and builds a blob on top of the block. That blob blocks airflow, rips wires and eventually drags the thermistor or heater out with it. Related problem: the grub screws holding the heater and thermistor work loose as the aluminum block expands and contracts, and the cartridge can slide right out mid-print.

1. Heat the hotend to ~240 °C, power the printer off, and pick the blob away with a wooden stick — not a screwdriver, or you'll tear wires and short contacts.
2. Strip the hotend while it's still hot: back the nozzle out with a 7 mm wrench while holding the block, then the heatbreak.
3. Check whether the heatbreak was loose in the block — that's usually the culprit.
4. Reassemble so the nozzle and heatbreak butt firmly together inside the block, and do the final nozzle tighten with the hotend at 250 °C.
5. Check the thermistor and heater grub screws, and make sure the silicone sock is on — without it the part fan chills the block and trips thermal runaway.
6. Run a PID tune afterwards and re-check the inductive probe height.

15. Extruder clicking and skipping

Clicking is the feeder gear losing grip on the filament. On the Kobra 2 the tension screw sits on the side of the head housing, next to a molded arrow and the word "Tighten". Anycubic's own order of operations: check the spool isn't binding and the filament hasn't jumped off the holder, tighten the screw clockwise, then open the extruder and clear filament dust from the gear teeth.

Set tension by the marks on the filament: pull a length back out and you want clear tooth impressions while the strand stays round. Flattened means too tight, no marks at all means too loose. Stiff PLA wants more pressure, soft TPU less. And remember TPU loves to wrap itself around the gears — if filament stops moving entirely, you'll have to take the extruder apart.

16. The stock profile's 6 mm retraction clogs the hotend

Anycubic's bundled profiles ship with retraction around 6 mm. That's fine on a bowden setup and about six times too much for the Kobra 2's direct drive: molten plastic gets yanked up into the cold zone of the heatbreak, solidifies and forms a plug. Symptoms are holes in layers, missing lines and oozing after every travel move.

• Start at about 1 mm and tune from there — that's the direct drive ballpark.
• Retraction speed is capped by the firmware's 80 mm/s max extruder feedrate. Your slicer will happily send more; the printer ignores it.
• Dry your filament before tuning retraction — wet plastic strings no matter what your settings say.
• Swapping the stock PTFE for Capricorn XS noticeably lowers friction and improves retraction behavior.
• Running a bimetal heatbreak? Go lower still.

17. Bed wires crack: temperature errors and a fire risk

Two looms run to the bed: a thin one for the thermistor and a thick 24 V one for the heater. The bed shuttles back and forth thousands of times, the wires flex at a single point right behind the plastic cap, and the strands inside the insulation start snapping. First you get erratic temperature readings and random MINTEMP or THERMAL RUNAWAY errors mid-print; later the error greets you at power-on.

1. Prevention: wrap a few layers of self-fusing tape right behind the plastic cap so the bend spreads over a length instead of one spot.
2. Sturdier option: slide a soft spring over the loom with heat shrink inside so the coils don't chafe the insulation.
3. When replacing, use longer and more flexible silicone wire and rethink the routing while you're at it.
4. Check the thermistor with a multimeter: the bed NTC should read about 100 ± 15 kΩ at 25 °C.

18. Heating errors: telling a broken wire from a dead board

"Hotend NTC abnormal", "Hotend heater abnormal" and "Hotbed NTC abnormal" sound alarming, but the diagnosis is simple and fully documented in the official wiki. Worth knowing the thresholds: hotend thermal protection trips if temperature drops more than 10 °C in 35 seconds; for the bed it's 2 °C in 20 seconds.

19. The filament sensor pauses prints for no reason

Inside the sensor housing is an ordinary microswitch with a metal lever that the passing filament pushes aside. Over time the lever loses springiness or filament dust works its way into the mechanism, and the printer decides mid-print that you've run out of plastic.

1. Pry the housing open carefully with a thin screwdriver — it's glued, so take your time.
2. Bend the metal lever slightly outward so it presses harder against the filament. Don't overdo it: the lever still has to trigger the switch.
3. Blow the mechanism out with compressed air — filament dust is a common culprit.
4. Check the switch with a multimeter: it's normally open and closes when filament passes through.
5. No luck? The sensor is cheap and swaps out whole.

20. The advertised 300 mm/s only exists on the box

Not a fault, just a mismatch in expectations that has people chasing quality for months. Anycubic's own Kobra 2 FAQ recommends 150 mm/s at 2500 mm/s² acceleration — half the marketing number. Independent measurements by Notebookcheck back that up: ripple shows on walls from 220 mm/s, and above 240 mm/s the vibration is bad enough to walk the printer across the table.

• The quality sweet spot is 100–150 mm/s with 2000–2500 mm/s² acceleration.
• Put the printer on a heavy, solid surface — the vibration at speed is real and obvious.
• 59 dB(A) in normal operation and up to 72 dB(A) flat out: this is not a bedroom machine.
• Lead screw noise above 200 mm/s is officially considered normal by Anycubic, not a defect.
• Pick layer heights that are multiples of 0.04 mm (0.12 / 0.16 / 0.2 / 0.24 mm) — whole motor steps on Z, no microstepping.

21. Bed temperature swings by five degrees

Set to 60 °C, the Kobra 2 bed measured between 53.6 and 58.4 °C: the factory PID values simply aren't dialed in. For PLA that matters — 60 °C is right at the glass transition, and running five degrees low changes adhesion noticeably. There's no insulation underneath either, so reaching 110 °C takes over five minutes.

Fix it with a PID tune. The printer has no terminal, so you'll need OctoPrint or Pronterface over USB-C: M303 E0 S220 C7 tunes the hotend, the bed uses M303 E-1 S60 C7, then you save the values to the printer's memory. While you're at it, a layer of insulation under the bed speeds up heating and reduces the swing.

22. The printer won't see the card and "won't print"

"My Kobra 2 won't print" usually means the printer can't see the file. This model has strict rules, and breaking any of them gets you an empty file list or an "SD Init Fail" message.

• The card goes in the slot on the mainboard (front right), not the one next to the screen — files in that one aren't read.
• Files must sit in the card's root: the printer doesn't open folders.
• Latin letters and numbers only, extension .gcode only.
• Format as FAT32 with a 4096-byte allocation unit, full format rather than quick.
• Up to 32 GB. The printer is picky about cards — sometimes you have to try a few.

23. PrusaSlicer throws an error when slicing: ArcWelder

A Kobra 2-specific trap. The bundled PrusaSlicer profiles put a call to ArcWelder.exe in Print Settings → Output options → Post-processing scripts — a tool that converts line segments into arcs. But the ArcWelder file itself lives on the included card, in Files_English_Anycubic Kobra 2 → Prusa Slicer, and you have to copy it into PrusaSlicer's root folder by hand. No file, and every slice ends with "PrusaSlicer error".

Both halves have to be in place: the post-processing line and the file in the program folder. If you don't need ArcWelder, just delete the line and slicing works fine. Step-by-step with screenshots is in the official wiki.

24. Black screen and the 115/230 V switch

The Kobra 2 power supply is a 400 W, 24 V, 17 A unit, and it's universal: there's a voltage selector switch on the back. Check it before you first power on. Plugging into 230 V mains with the switch set to 115 V kills the supply.

1. Screen stays dark: check the voltage selector and the fuse in the power switch housing.
2. Look inside: is the red LED on the mainboard lit? If not, check the indicator on the PSU.
3. PSU indicator dark means the supply is dead; PSU lit but board LED dark means the board is dead.
4. Both lit but the screen is black — reseat the display ribbon cable, that's the most common cause.

25. "Homing Failed: X/Y" and a Z axis that won't home

The message means the carriage reached the end of travel without the switch firing. Four causes: the switch has shifted and the carriage misses it, a connector is loose or a wire is broken, the switch itself has died, or — rarely — the board.

1. Push the head (or bed) toward the switch by hand and watch whether the lever actually gets pressed.
2. Check the connectors at both ends — at the switch and at the mainboard.
3. Start a homing move and press the lever with your finger halfway through. If motion stops, the switch and wiring are fine and it's a positioning problem.
4. If it doesn't stop, kill the power immediately so the carriage doesn't crash, then check the switch and wire with a multimeter.
5. For Z there's one more check: disconnect the motor and turn the lead screw by hand — it should turn without binding. The switch should see about 3.3 V with the printer on.

26. Stock firmware limitations

The Kobra 2 runs Marlin-based firmware, and some problems can't be "fixed" simply because the feature isn't there. Knowing the factory values helps you understand what's actually adjustable.

The nuclear option is Klipper: the Huada HC32F460 MCU on the Trigorilla Pro B V1.0.2 is officially supported, and the firmware flashes from the card like any other build. Know the trade-off first: the stock display stops working (the interface it hangs off isn't supported in Klipper), so the printer is driven exclusively from an external host running Mainsail, Fluidd or OctoPrint. In exchange you get Pressure Advance and Input Shaper, which the stock firmware badly lacks. You can flash back to factory firmware whenever you want.

Kobra 2 error message reference

Monthly maintenance that prevents most of this

General FDM problems

Beyond the Kobra 2's own quirks you'll run into the usual FDM problems — they behave the same on any printer, and we've covered each one in its own deep dive:

• First layer won't stick or curls up — plate prep, temperatures, Z-offset
• Clogged nozzles and heat creep — cold pulls, hotend teardown, prevention
• Stringing and wisps between parts — retraction, temperature, moisture
• Warping and lifting corners — especially relevant on the open-frame Kobra 2
• Layer shifts and ghosting — belts, acceleration, vibration
• Under- and over-extrusion — e-steps and flow calibration
• Drying filament — what to do with wet plastic
• Printer maintenance schedule — what to check and how often
• Fumes and ventilation — worth reading for an open frame in a living space

Also useful: setting up OrcaSlicer instead of the bundled profiles, the Anycubic filament guide, a comparison of the whole Kobra lineup if you're thinking about upgrading, and the Kobra 3 known issues breakdown for this machine's successor.

FAQ