Elegoo Neptune 4 Mods: 27 Upgrades That Actually Work

The Elegoo Neptune 4 is a 2023 open-frame bed slinger: 225×225×265 mm build volume, direct drive, a 300 °C hotend, a 110 °C bed and real Klipper on board for $219. That Klipper install is the whole reason this printer is worth modding — most of what needs a new mainboard on other budget machines is just a config change here. Below are 27 mods owners actually run, from a free printed tension arm to open firmware and an eddy-current bed scanner. If you haven't read the failure list yet, start with 22 known Neptune 4 issues — half of what follows exists to fix those.

The list runs cheap-and-safe to deep-and-risky. Each mod is tagged: "easy" means an evening with no teardown, "medium" means you should understand how the machine moves, "hard" means a full teardown, a console and a real chance of ending up with a printer that doesn't boot. Prices come from the Printer Hub catalogue.

Most of this runs on the hex keys in the box. Two things worth buying separately: a caliper (for measuring rails, nozzles and first-layer thickness) and decent flush cutters instead of the ones Elegoo ships.

1. A spare extruder tension arm

The plastic tension arm cracks at the pivot, and it's the single most common failure across the whole Neptune 4 line. The nasty part: a broken arm means no filament feed, so the printer physically cannot print its own replacement. Print it before it breaks, not after. Superglue doesn't hold — spring tension splits the joint again within a few filament changes.

• costs nothing and prints in about twenty minutes
• Elegoo warranties the factory part for six months only, and buying one runs close to $30 with shipping
• the model verified on the base Neptune 4 is Elegoo Neptune 4 extruder lever — 217 likes, 1,516 downloads
• one owner running a beefed-up ABS-GF version got 3,000 hours out of it on abrasive filament

Difficulty: easy. Cost: free, print in PETG or PLA+ at 100% infill. Fit: the author confirms the base Neptune 4; the eight-iteration redesign Neptune 4 Max/Plus Extruder Tension Arm was only tested on Plus and Max. If it already snapped and you have nothing to print with, the whole assembly is a catalogue part.

2. A second PEI sheet

The most boring mod with the fastest payoff. One plate cools while the next print starts on the other — no waiting. The second use case: a worn PEI layer stops holding the first layer, and instead of glue-stick rituals you just flip or swap the sheet. For owners whose first layer won't stick, a fresh sheet often ends the story.

• the stock sheet is 235×235 mm, double-sided, on spring steel
• $6.26 in the catalogue against $19.99 for the same part in Elegoo's own store
• texture depth varies between sheets, so re-do your Z offset after swapping
• worth noting from the same thread: for some owners it was the firmware, not the sheet, that fixed adhesion — two independent levers, don't conflate them

Difficulty: easy. Cost: $6.26. Fit: any Neptune 4 with the 225×225 mm build area. Source: the r/ElegooNeptune4 thread.

3. A bed that stays put: screw locks and silicone spacers

The stock bed springs are under-tensioned and slowly give up under vibration. The bed creeps down, Z offset drifts print to print, and you re-chase the first layer every time. The teardown of this in r/elegoo pulled 246 upvotes — it's a design trait, not bad luck. Three things fix it: printed screw locks, silicone standoffs instead of springs, and one Klipper command.

• Bed Screw Lock — 348 likes, 2,392 downloads, about $0.30 of filament
• silicone standoffs run $3-5 and don't sag when the bed heats
• SCREWS_TILT_CALCULATE in the Fluidd console tells you exactly how far and which way to turn each knob — paper-shimming never gets that close
• owners running this combo report going months without touching bed levelling

Difficulty: easy. Cost: under $5. Fit: the screw lock model is listed for the Neptune 4 Pro, so test-fit on the base machine — the knob geometry matches but check before you commit. The Klipper console lives at the printer's IP, see mod #13.

4. A cable chain for the printhead loom

The head loom flaps and rubs on every X move. A worn loom throws temperature spikes and the "ADC out of range" error, and the printer dies mid-print — one of the more infuriating faults on this machine. A cable chain takes the strain off the bend and keeps the loom out of the carriage's path.

• the most downloaded printed Neptune 4 mod we found: 1,348 likes and 16,681 downloads
• print it in PETG — PLA sags near a hot bed
• the package includes a Z-axis mount and a tension strap
• there's an alternative 90-degree version with 398 likes and 4,882 downloads
• a replacement extruder cable assembly runs $11.99, so the chain pays for itself the first time it saves one

Difficulty: easy — about two hours of printing and half an hour of assembly. Cost: free. Fit: base Neptune 4 and 4 Pro. Model: Elegoo Neptune 4/4PRO Cable Chain.

5. A printed spool holder

The stock holder is sized for a full 1 kg spool. Smaller ones rattle around, filament comes off in jerks and the feed starts stuttering. The printed version fits tighter and lets you hang two spools if you're testing materials. Small thing, but it's the model most owners print first on a new machine.

• 800 likes and 7,502 downloads — this author's most popular model
• the description explicitly lists Neptune 3 Pro, Plus, Max and the entire Neptune 4 line including the base unit
• mounts with the stock screws, no supports, 0.2 mm layers
• the base-model alternative is Spool Holder Elegoo Neptune 4 with 277 likes and 2,951 downloads

Difficulty: easy. Cost: free. Fit: the author confirms the base Neptune 4. Model: Elegoo Neptune 3 and 4 replacement filament spool holder. If the spool itself is wet, no holder helps — that's a drying job.

6. X and Y belt tensioners

Stock belt tension rides on a single screw and slowly slips. A loose belt means ghosting on walls and layer shifts, and at 250 mm/s you see it immediately. Printed tensioners give you an actual adjustment range instead of "tightened until it felt right", and they hold after you've had the gantry apart.

• Neptune 4 Belt Tension Stopper: 325 likes, 3,077 downloads, and the single 3mf holds separate versions for base, Pro, Plus and Max
• a fresh GT2 6 mm belt is $2.01 in the catalogue — cheaper than living with a stretched one
• there's a separate single-idler tensioner for the Z belt: 138 likes, 548 downloads
• any mechanical mod means re-tensioning belts anyway, so people fit these up front

Difficulty: easy. Cost: free, plus a belt if yours is stretched. Fit: the archive includes a base Neptune 4 version. Model: Neptune 4 Belt Tension Stopper.

7. Vibration isolation: what works and what doesn't

A bed slinger shakes whatever it stands on, and the whole house hears it. Half the advice on this doesn't survive a sound meter, though. One Neptune 4 Pro owner read 54 dB both before and after putting the printer on a concrete paver with foam. Turn the part cooling off and the same machine drops to 40 dB. The floor isn't the problem. The fans are, so start there (mods #9 and #10).

• soft foam or a yoga mat on its own makes it worse — now the whole table resonates
• what does work is rigid mass (a concrete paver) with a damper underneath, not foam alone
• printed anti-vibration feet for the base Neptune 4 have 275 likes and 3,037 downloads, and the author honestly says they help "to a degree"
• isolation matters less for silence than for keeping vibration from bouncing back into the frame and marking your walls

Difficulty: easy. Cost: a paving slab and a sheet of foam. Fit: anything. Sources: the noise measurements thread and the feet model.

8. Nozzles: hardened steel and a size set

Here's the Neptune 4's real annoyance: the nozzle is proprietary. Overall length 18 mm, M6×1 thread 9 mm long — the threaded section runs 2 mm longer than a standard RepRap nozzle and the whole part is 5.5 mm longer. A plain MK8 or V6 does not drop in. The heat break is just as special: its air gap is 1 mm longer than the closest Slice Engineering Copperhead variant.

• hardened steel matters if you print carbon- or glass-filled filament; brass wears out in tens of hours on that stuff
• the brass size set gets you 0.6 and 0.8 mm — roughly double the draft speed with no strength penalty
• one owner reported over 1,000 hours on an $18 hardened nozzle that still measured 0.4 mm
• Volcano and CHT nozzles on AliExpress are sold for the Plus and Max only — different heater block, they will not fit the base machine
• if you want out of the proprietary ecosystem entirely, that's mods #21 and #22

Difficulty: easy, but only unscrew the nozzle on a hot hotend — cold threads strip, and Elegoo calls this out in its own procedure. Cost: $2.06 for the hardened set, $7.62 for the brass set. Fit: Neptune 4 and 4 Pro. If your current nozzle is already blocked, deal with the clog first — a new one will jam the same way.

9. Switch off the rear fan bar

Four ball-bearing 4020 blowers on the gantry are the main source of the howl. They also blow small parts off the first layer and create a temperature gradient that lifts prints off the bed. Owners rank "remove the aux fans" first among noise fixes: "you don't need them for any material, it's just a noisy gimmick." Tom's Hardware makes the same point — the bonus fan can be switched off if you're not chasing headline speeds.

• measured on a real machine: 54 dB with cooling on, 40 dB at zero fan
• the bar has its own switch and a separate DC 24 V connector, so it comes off physically with no firmware edits
• on the touchscreen it's the Fan Control entry under Settings
• for PLA at 250 mm/s the two head blowers are enough; the bar only earns its keep at the very top of the speed range
• as a bonus, the classic "small parts got knocked off the plate" complaint goes away

Difficulty: easy, two minutes. Cost: free. Fit: base Neptune 4 and 4 Pro. Sources: the noise ranking thread and the Tom's Hardware review.

10. A 5015 blower shroud

The stock pair of 4015 blowers is loud and cools unevenly — one side of the part chills faster than the other. The community rebuilt the head around 5015 blowers: more airflow, less noise, because a bigger impeller moves the same air at lower RPM. This is the second most effective noise fix after killing the rear bar.

• the popular one is Fan Shroud V5 by OrzOrzOrz: 715 likes, 3,387 downloads
• the archive ships separate files for base and Pro — they differ in accelerometer clearance, 15 mm versus 19 mm
• the stock 4015 moves to the heatsink in this layout, and its connector polarity has to be flipped
• the triple-5015 variant is overkill on airflow: you end up dialling part cooling down to roughly 60% in the slicer
• the compact alternative is PROXIMITY_45 — two screws instead of the stock set, and the head stays on the gantry

Difficulty: medium, about two hours with the head apart. Cost: $3-9 for a pair of 24 V blowers plus filament. Fit: base Neptune 4 has its own files in the archive.

11. A nozzle brush with a Klipper macro

After heat-up there's a blob hanging off the nozzle, and it goes straight into the first layer. Pricier printers have a wiper for that; here you build one. A printed mount at the edge of the bed, a cheap wire brush, and a macro in your start G-code that drags the nozzle across the bristles before every print. Set it once and forget it.

• the mount and a ready-made macro ship in the same model — 25 likes, 137 downloads, published 27 July 2025
• brass nozzles are safe: the nozzle wears out from printing long before it wears out from bristles
• hardened and coated nozzles are even less bothered
• as a bonus, the smeared blob that fakes an elephant's foot on the first layer disappears

Difficulty: medium — you need to edit start G-code in the slicer or printer.cfg. Cost: a print and a brush. Fit: base Neptune 4 and Neptune 3 Pro; the author warns that the Neptune 4 Pro has different bed mounting holes and he never published a version for it. Source: Neptune 3 Pro / Neptune 4 Nozzle Brush Mount.

12. PID tuning for the bed and the hotend

Factory heater coefficients are averaged — tuned for any unit off the line, not yours. After calibration the temperature holds steadier, which shows up directly in first layers and wall finish. It's free, takes fifteen minutes and runs through the web interface; Elegoo even publishes the procedure with a pointer to the Klipper docs.

• open the config file at the printer's IP, replace the watermark block with pid and enter the starting values pid_kp = 68.835, pid_ki = 2.217, pid_kd = 534.331
• then run PID_CALIBRATE HEATER=heater_bed TARGET=60 in the console and commit with SAVE_CONFIG
• for the hotend it's the same command with HEATER=extruder and your material's working temperature
• the Neptune 4 Pro has a two-zone bed, so the second zone is tuned separately as heater_bed1 — the base machine has one zone
• the printer's IP is on the screen under Settings — About Machine

Difficulty: medium, but risk-free: the command only writes coefficients. Cost: free. Fit: the whole line. Official procedure: Elegoo Wiki; the theory is in the Klipper docs.

13. The web interface at the printer's IP, and thumbnails on screen

Klipper on the Neptune 4 is buried under Elegoo's own shell. Tom's Hardware put it best: "It seems that Elegoo decided the best way to run Klipper is to not see it at all." Meanwhile a full Fluidd sits at the printer's IP address in any browser — you just have to know to look. This isn't a mod so much as unlocking half the machine for free.

• grab the IP from Settings — About Machine and type it into a browser on the same network
• the web UI gives you file uploads, the Klipper console, printer.cfg editing and every calibration the touchscreen hides
• Settings — Authentication hands out an API key for OrcaSlicer, Cura, PrusaSlicer and LycheeSlicer, so prints go straight from the slicer
• on-screen model thumbnails come from the ElegooNeptuneThumbnails plugin for Cura, with post-processing scripts for PrusaSlicer and OrcaSlicer
• the base Neptune 4 has exactly two paths in: an Ethernet cable and a USB stick

Difficulty: easy. Cost: free. Fit: the whole line. Guides: web page control and remote printing. For slicer setup see our OrcaSlicer guide.

14. Wi-Fi via a USB dongle

The base Neptune 4 and the Pro have no wireless at all — Wi-Fi is a Plus and Max feature. Tom's Hardware flags this directly: no Wi-Fi makes reaching Klipper awkward. Running Ethernet across the room to your router is a poor answer, so owners fit a USB dongle. Not any dongle: Elegoo names two that come up driver-free.

• the tested adapters are the Mercury MW150US and the TP-Link TL-WN725N, both driver-free
• the printer only sees 2.4 GHz — dual-band adapters won't work
• split your router into separate 2.4 and 5 GHz SSIDs and pin the 2.4 GHz channel between 1 and 8, or the printer won't find the network
• Elegoo explicitly advises against phone hotspots
• on stock firmware the procedure is fiddly: you edit wpa_supplicant-wlan0.conf inside the update package and reflash
• on OpenNept4une it's just sudo nmtui, and far more adapters are supported

Difficulty: medium on stock, easy on OpenNept4une. Cost: a few dollars. Fit: base Neptune 4 and 4 Pro; Plus and Max don't need it. Guide: Elegoo Wiki. What to do with a networked printer next is covered in our remote access guide.

15. A camera watching the print

There's no camera on the Neptune 4, but the service for one already ships in the firmware — you just enable it over SSH. This is the single most upvoted recipe in the model's subreddit: 89 points and 143 comments. No custom firmware needed, it all works on stock.

• SSH in as mks with the password makerbase, then run sudo systemctl enable webcamd and sudo systemctl start webcamd
• the camera then turns on in Fluidd under Settings — Cameras
• confirmed working: Logitech C270, C920, C922 and the Aukey PC-W3
• known gotcha — the camera doesn't come back after a power cycle; fix it with ExecStartPre=/bin/sleep 5 in the crowsnest unit, or restart the service by hand
• the printed C270 mount replaces the left X-carriage cover: 62 likes, 516 downloads

Difficulty: medium — you need an SSH client and basic console comfort. Cost: whatever the camera costs. Fit: the whole Neptune 4 line. Sources: the webcam thread and the C270 mount. For real failure detection see mod #26.

16. Fresh carriage wheels

POM wheels wear and the carriage starts to rock: ripple on walls, geometry drifting. On the Neptune 4 this has its own subplot — some owners can't get the eccentrics tight enough to kill the play at all. The distinction matters: if the wheels tighten but the slop stays, the wheels aren't your problem.

• a full wheel kit is $3.43 in the catalogue — the cheapest mechanical fix on this list
• adjustment happens at the eccentric nuts with an open-end wrench, no carriage teardown
• if the play survives, the X gantry is skewed — Elegoo has a dedicated procedure for reseating it
• worn wheels look exactly like a loose belt, so check tension first (mod #6)
• the nuclear option for the same problem is linear rails, mod #18

Difficulty: easy. Cost: $3.43. Fit: Neptune 3 and 4. Procedures: eccentric adjustment and wheels that won't tighten.

17. Z-axis stabiliser rods and Oldham couplers

Two unsupported lead screws wobble at the top, and a rigid motor coupling on a slightly bent screw pipes that runout straight into the bed. That's where the waves on side walls and the bed mesh that changes between prints come from. Fix it from both ends: stabiliser rods up top, Oldham couplers down below to decouple motor from screw.

• the Funssor stabiliser rod kit is $35.90 in the catalogue
• Oldham couplers are the cheap half of the same cure — one owner says they came in "way less than rails" and his probe accuracy went up too
• spec for this machine: T8 lead screw, 18.2 mm hole spacing measured on the Pro chassis
• both Z screws on the Neptune 4 run off one driver through a shared belt, so gantry skew never self-corrects — you square it by hand
• maintenance: wipe the screws with a lint-free cloth every two months and apply a thin film of white lithium grease; excess grease collects dust and turns abrasive

Difficulty: medium. Cost: $35.90 for the rods, a few dollars for couplers. Fit: Neptune 3 and 4. Sources: the couplers-versus-rails thread and Elegoo's lead screw schedule.

18. Linear rails instead of wheels

The biggest mechanical rebuild on the list. Wheels and eccentrics disappear entirely, carriages ride on ball bearings. People do this for repeatability, not speed: one owner's Y-axis bed mesh spread dropped from 0.7 mm to 0.2 mm after the Y rail alone. The second effect is quieter steppers — "far less to accomplish the same movements."

• budget 4-5 hours and a full gantry teardown
• the catalogue route is survivable: Y-axis rails $13.56, an MGN12H Z rail $32.59, the X and Y kit $79.75
• it can also spiral: one Neptune 4 Max owner paid $73 for X, $158 for Y and $129 for Z in HIWIN rails, plus $60 on a belted Z conversion and $3 on silicone standoffs — $363 for the mechanics alone
• AliExpress listings are usually tagged for the Neptune 3 Pro / 4 or for the Max — check mounting dimensions against the base machine before buying
• re-run the bed mesh and re-tension the belts once it's together

Difficulty: hard, half a day. Cost: from $13.56 for a single axis; the full catalogue set lands near $126, while that owner's HIWIN rails came to $363. Fit: the catalogue kits are listed for Neptune 3 and 4. Sources: the install write-up, the Y-axis measurement and the counter-example.

19. Hardened drive gears

Drive gears grind down on abrasive filament and start slipping: the feed clicks and you get under-extrusion. One owner measured before and after: 15-18 mm³/s on PETG with stock gears, 15-25 mm³/s after the swap and a re-calibration, with no skipped steps. The same machine ran PET-CF at 295 °C and 15 mm³/s.

• the flow gain shows up on PETG and composites; on PLA there's almost nothing in it
• a kit is $7.52 in the catalogue
• re-calibrate extrusion afterwards or you'll walk straight into over-extrusion
• the Russian-language community pushes back: "the importance of this is heavily overblown for ordinary home printing"
• same source, with numbers: one machine logged around 800 hours on PLA, PETG and ABS and showed no gear wear on teardown

Difficulty: medium, the extruder comes apart. Cost: $7.52. Fit: Neptune 4 series. Verdict: worth it if you run carbon- or glass-filled filament regularly; for PLA and PETG the stock gears last years. Sources: the 3,000-hour teardown and the 4PDA thread.

20. The hotend: consumable and upgrade

The Neptune 4 hotend is a consumable. After a blob of death — where molten plastic sets around the block and welds the heater and thermistor into one lump — replacing the assembly beats scraping it. The other path is a deliberate upgrade. On MicroSwiss the community is blunt: "just do it, it's a night and day difference with print quality," and the swap takes about fifteen minutes.

• the stock assembly is $11.16 in the catalogue against $19.99 in Elegoo's own store
• 24 V 50 W heater, NTC 100K thermistor rated to 300 °C, 20×16×15 mm block
• Plus and Max run an 80-98 W heater, so their spares do not fit the base machine
• for several owners the MicroSwiss swap also ended a run of repeat blobs
• re-do the Z offset after any hotend change — the nozzle height moves

Difficulty: medium, roughly fifteen minutes on a hot machine. Cost: $11.16 for the stock unit. Fit: Neptune 4 and 4 Pro. Elegoo's blob teardown is here, the community view is in this thread.

21. A CR6-SE copper block and an MK8 nozzle

The most interesting budget mod of the past year: an owner escaped Elegoo's proprietary nozzles into the MK8 ecosystem and doubled his flow rate for $5-10. The reasoning is simple. Aluminium's thermal conductivity is 200-235 W/m·K, copper's is 390-400. The stock aluminium block just can't push heat into the melt fast enough at speed, and flow tops out around 10-14 mm³/s.

• the Creality CR6-SE block matches the Neptune 4 mounting hole spec — nobody makes a copper block for this printer directly
• the stock block is 15 mm tall, the CR6-SE is 10 mm; a nylon washer on the heat break closes the gap, not a metal spacer
• the nozzle is a nickel-plated MK8, which also stops PETG clinging to the tip
• measured result: the OrcaSlicer max volumetric speed tower for PETG reached 20.55 mm, which works out to 20.27 mm³/s
• the stock M2 mounting bolts end up too short, you need slightly longer ones
• expect to re-do Z offset and bed mesh, and treat the old thermistor bead as extremely fragile

Difficulty: hard, the thermistor transfer needs care. Cost: $5-10. Fit: Neptune 4 and 4 Pro (Plus and Max use a different block). Source: the author's write-up.

22. A Bambu Lab hotend adapter

The other escape route from proprietary nozzles: a printed adapter that puts a Bambu Lab-format hotend on the Neptune 4 carriage — ceramic heater, cheap swappable nozzles, dozens of variants on any marketplace. The mod is fully reversible: the stock thermistor stays, and the original hotend goes back with no trace.

• 115 likes and 526 downloads, published 17 January 2025
• shopping list: three 5015 blowers, 6×M3×20, 2×M3×6, 2×M3×16, two M3 nuts and a 27 mm length of PTFE tube
• the heater comes from the Bambu side and plugs straight in
• the finished assembly sits about 1 mm longer, so re-level the bed after it's together
• in an update the author honestly suggests looking at off-the-shelf "upgrade hotends for Neptune 4" built on the same ceramic heater — simpler than the full adapter

Difficulty: hard. Cost: a print plus $10-20 for a third-party hotend. Fit: base Neptune 4 and 4 Pro share the same hotend; the kit was never tested on Plus or Max. Model: Bambu Lab Hotend Kit for Elegoo Neptune 4.

23. OpenNept4une — open firmware instead of Elegoo's

The headline mod for this printer, and the only one that fixes behaviour rather than hardware. The project replaces Elegoo's shell wholesale with stock Klipper on a current Armbian. The repo is alive: 663 stars, last push 21 July 2026, last commit to main 10 March 2026, GPL-3.0. The current release is v0.1.7 from 22 November 2025 — Armbian 25.11, Linux 6.16.12, Klipper v0.13.

The base Neptune 4 is a first-class citizen: there's a dedicated n4 profile in the repo and separate images for ZNP K1 v1.0 and v1.1 boards. The strongest argument is a documented stock-firmware bug the project fixes: PROBE_CALIBRATE saves the Z offset as 0.0 and the Z axis never applies bed mesh compensation. One owner tested that across five Neptune 4 Max machines and every released firmware version; on OpenNept4une the identical procedure just works.

• Fluidd on port 80 and Mainsail on port 81 — two web interfaces out of the box
• KAMP adaptive meshing: the probe only touches the area the part will occupy
• axis twist compensation, firmware retraction, ready-made OrcaSlicer profiles
• support for a wider range of USB Wi-Fi adapters and a built-in updater
• the stock touchscreen runs through a separate project, display_connector, still in beta — the repo is alive, last push 11 June 2026

Installation: pull the bottom cover, remove the eMMC module (two screws), flash the image with Raspberry Pi Imager or balenaEtcher, reassemble, SSH in as mks with the password makerbase, run ~/OpenNept4une/OpenNept4une.sh and follow it with the "Update MCU & Virtual MCU Firmware" step. An eMMC-to-USB adapter runs about $11 and is bought separately.

• there is a way back: put ElegooSD-restore.bin on a FAT32 microSD card twice, named X_4.bin and elegoo_k1.bin, and power the printer for two minutes
• a full system rollback means flashing the factory image back onto the eMMC — and the images differ between the ribbon-cable and Type-C revisions, so check Elegoo's guide
• some owners buy a second eMMC module and keep the factory system on it, which turns switching firmware into swapping one board
• the mid-print crashes on the v0.1.6 release were closed on 5 January 2026 — the root cause was a Klipper bug patched in December
• the most common complaint isn't the firmware, it's the documentation: discussion moved to Discord, and "finding a tidbit of info from 8 months ago is far too inefficient"

Difficulty: hard, an evening's work and a willingness to read a console. Cost: free plus the eMMC adapter. Fit: the base Neptune 4 is officially supported. Sources: the project repo, issue #352 on the mid-print crashes and the Z-offset write-up.

24. An ADXL345 and real input shaping

No accelerometer ships in the box, and the factory input shaper values are generic. There is a header for one on the board though: on the ZNP K1 schematic it's labelled ADXL345, and it's populated on both v1.0 and v1.1. Tom's Hardware missed it and wrote that there's "no visible way to hook one up" — technically fair, since it isn't brought out anywhere and isn't documented.

Elegoo's official answer, verbatim: only the ADXL345 is supported, it must be wired to the board header's pinout, there is no tutorial from them, and "it is recommended to print the test file according to the official klipper tutorial." The Neptune 4 Plus and Max ship a Y-axis accelerometer from the factory; the base model and the Pro do not.

• wiring from the community guide: black GND, white 3V3, grey CS, purple SDO, blue SDA, green SCL; INT1 and INT2 stay unconnected
• run ACCELEROMETER_QUERY to confirm the sensor, then TEST_RESONANCES AXIS=X and AXIS=Y
• feed the CSVs to calibrate_shaper.py and write shaper_freq and shaper_type into printer.cfg
• the [resonance_tester] section takes accel_chip: adxl345, accel_per_hz: 75 and a probe point
• printed mounts confirmed for the base machine are the Mellow Fly ADXL345 Mounts — you'll need four M3×6 threaded inserts plus M3×6 and M3×18 screws

Difficulty: medium — no soldering iron required, just a tidy cable and a console. Cost: $9-15 for the module. Fit: base Neptune 4 and 4 Pro. Sources: Elegoo's official answer, the Klipper docs and mounts for the base model.

25. A Cartographer or Beacon bed scanner

Elegoo's inductive probe takes 36 or 121 points and dislikes a hot bed. An eddy-current scanner takes hundreds of points in under a minute and brings its own accelerometer, which knocks out two mods at once. This is the most praised combination in the community: the Cartographer-plus-OpenNept4une post pulled 76 points and 81 comments, and the owner's verdict was "it's every bit as reliable as my modified Ender 3 now — I can press print and walk away."

• roughly a 900-point adaptive mesh in well under a minute
• the same probe supplies an ADXL345 for SHAPER_CALIBRATE
• it plugs into the front USB-A port, standard 90-degree version, no CAN bus needed
• prerequisite: OpenNept4une first — this will not run on stock firmware
• you need a printed shroud: mounting the probe to the stock duct is out, "it's not stable enough to get consistent readings", and the shroud goes in ABS because the hotend is right there

Difficulty: hard. Cost: around $36 for the probe plus a printed shroud. Fit: base Neptune 4 over USB. If you don't want a scanner and your stock probe is misbehaving, replacing it is cheaper at $12.99. Source: the owner's write-up.

26. The Moonraker stack: spools, watching, phone

Once there's a proper Klipper on the machine, an ecosystem assembles around it: spool tracking, print watching and your phone instead of the touchscreen. Important caveat: most of this will not install on stock firmware, because Elegoo's Moonraker is modified and doesn't update. So treat this as a bundle with mod #23.

• Spoolman tracks filament: 2,733 stars, last push 20 August 2026; runs in Docker on port 7912, with a [spoolman] section in moonraker.conf pointing at http://localhost:7912
• Obico watches prints and flags failures: 189 stars, last push 2 June 2026; clone the repo, run install.sh, works against the cloud or your own server
• Mobileraker is the mobile client at 644 stars, connecting with the API key from the printer's web interface
• versions as of 21 August 2026: Klipper v0.13.0, Fluidd v1.37.4, Mainsail v2.18.2 — all three actively developed
• KlipperScreen is not the answer for the stock display: it targets a separate HDMI panel, while the built-in screen is handled by display_connector

Difficulty: hard, but step by step. Cost: free. Fit: on top of OpenNept4une only. More on spool tracking in our Spoolman write-up, and on running your own print server in this guide.

27. An enclosure

The Neptune 4 is open, and that's its main material limit. The bed reaches 110 °C, which is plenty for ABS and ASA — the blocker is the lack of an enclosure: without one the part catches a draft and lifts at the corners. An enclosure solves two problems at once: it holds chamber temperature and it noticeably muffles the machine.

• Elegoo's own enclosure fits Neptune 2, 3 and 4 and costs $35.69 in the catalogue against $39.99 in their store
• in the noise thread an enclosure ranks alongside fan swaps: "an enclosure did wonders for mine, made from wood and glass"
• a DIY wood-and-glass box comes in cheaper than the official one
• PLA overheats inside a closed box, so leave the door open for it

Difficulty: easy. Cost: $35.69 for the official one. Fit: Neptune 2, 3 and 4. Source: Elegoo's product page.

Myths and stale advice

Some of the popular Neptune 4 advice either doesn't work or was true on one specific model and spread without the caveat. Here are eight of them, and what checking actually showed.

Where to start

Do all of it and you end up like the Reddit thread where an owner spent $363 on rails and $400 on a multi-colour kit — $763 of mods on a $360 printer. A saner order exists: free things first, then whatever fixes the known weak spots, then money.

1. Print a spare tension arm (#1). Zero cost, twenty minutes, and you never end up with a printer that can't print its own spare.
2. Sort the bed out (#3). Screw locks, silicone standoffs and SCREWS_TILT_CALCULATE kill the most common complaint on this machine — drifting Z offset.
3. Open the web interface at the printer's IP (#13). Free, and it instantly gets you a console, config editing and network printing from the slicer.
4. Switch off the rear fan bar (#9). Two minutes, 14 dB quieter and fewer parts knocked off the plate.
5. Print the cable chain (#4). Cheaper than replacing a chafed printhead loom.
6. Run PID tuning (#12). Fifteen minutes in the console; steadier temperature means cleaner walls.
7. Only then the firmware (#23) and everything downstream of it: accelerometer, bed scanner, rails. That's an evening's work and a console you're willing to read.

One note on maintenance: half the "problems mods fix" are really maintenance. Wipe and grease the lead screws every two months, check belt tension and wheel preload — the full schedule is in our 3D printer maintenance guide. For printed mods, stick to platforms that keep models available; we covered where to find them separately.

Sources

• OpenNeptune3D/OpenNept4une — open firmware, release v0.1.7 of 22 Nov 2025
• Issue #352 — mid-print crashes on v0.1.6, closed 5 Jan 2026
• OpenNeptune3D/display_connector — stock touchscreen after reflashing
• Elegoo Wiki — official answer on ADXL345 support
• Elegoo Wiki — USB Wi-Fi adapter expansion
• Elegoo Wiki — hotbed PID calibration
• Tom's Hardware — Neptune 4 review, acceleration and real speeds
• The 3D Printer Bee — noise and print time measurements
• r6e.dev — ZNP K1 board and nozzle geometry teardown
• r/ElegooNeptune4 — Cartographer with OpenNept4une
• r/ElegooNeptune4 — CR6-SE copper block and MK8 nozzle
• r/ElegooNeptune4 — linear rail conversion
• r/ElegooNeptune4 — what actually reduces noise
• r/elegoo — why the bed drifts
• Printables — tension arm for the base Neptune 4
• Printables — printhead cable chain
• Printables — 5015 blower shroud
• Printables — ADXL345 mounts for the base model
• 4PDA — the 121-page Elegoo Neptune 4 thread
• 3DToday — owner experience and working speeds