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Elegoo Neptune 4 Pro 3D Printer Review and Upgrades. What Accessories, Mods, Fix Issues and Filament Do You Need With This Printer




Assembly tips

  • To make it easier to attach the gantry, set the printer on its side and mate the gantry to it and loosely tighten the screws. Then set it upright and lower the Z axis such that the print head is all the way down to the build plate. Set the printer at the edge of a table such that you can access the gantry assembly screw and tighten it down. Do the same for the other side.

  • Check the tightness of all the belts. If the X or Y-axis belts are loose, tighten them until there's no more slack.

Filament Sensor

In this video, I show how the filament sensor works, and how to reset after running out of filament.




Build Plate Adhesion Improvements

The stock textured build plate has poor adhesion with PLA and PLA Plus. It works ok with ASA (ABS). For PLA, the smooth build plateshown in the video below by CREALITY works better.


▶ CREALITY Build Plate -

Warped Build Plate

There's a design issue where the Y axis belt ends poke into the underside of the build plate, and can cause the build plate to warp if the leveling screws are tightened a lot. Watch this video to see the easy solution to that.

Z-Offset Issues (Inaccurate Z-Homing causes first layer to fail)

There are major issues with the Z-offset not remaining consistent. Many people report this issue. When you level the build plate using the sheet of paper and save that, it can be off by +/- 0.1mm when z homing is performed before the print starts. That means that the first layer is printed either too close to the build plate, and the nozzle scrapes through it, or it is too far away and the 1st layer doesn't adhere to the build plate.

Although the other mods I have done have improved build plate adhesion and prevented the warping of the build plate, the Z-offset continues to be inconsistent. It's as if the non-contact induction distance sensor gives inaccurate readings. (NOTE: Using the Fluidd interface over ethernet, I found that the bed probe sample tolerance is very precise with a sample tolerance of around 0.002mm. The issue is not that the inductive probe isn't precise, it's that it's inaccurate due to temperature changes.)

I thought about changing the number of [probe] samples in the printer.cfg file would help increase the precision of the z-homing distance, but the number of [probe] samples only affects the bed mesh probing cycle. The number of z-homing samples is controlled in the Kilpper firmware and there's no variable to change that (This post confirms that and there's no plan to change it). It does 2 cycles, and only uses the value of the final reading, not a mean of the 2. The only way to improve the z-homing accuracy is to slow down the speed for each cycle. I slowed it down to 5mm/s for the first and 2mm/s for the second. That actually seems to provide more accurate z-homing.

The main culprit of the Z-homing inaccuracy is heat, both in the build plate and nozzle. Before setting the z-offset, the build plate and nozzle need to be heated up for a while (This video of a Neptune 4 Max shows it taking 25 minutes to stabilize, and although the Max build plate is larger, the same concept applies to the standard Neptune build plate). Heating up the nozzle also affects the distance readings, changing by 0.03mm between 140C and 220C. Therefore, the bed and nozzle should be preheated for 20+ minutes before bed meshing probing, z-offset calibration, and z-homing. When changing filaments that require different build plate and nozzle temperatures, the bed mesh probing, z-offset calibration, and z-homing should be performed at the filament temps before printing.

Bed Mesh Probing

NOTE: Using the Fluidd interface over ethernet, I found that the bed probe sample tolerance is very precise with a sample tolerance of around 0.002mm. The issue is not that the inductive probe isn't precise, it's that it's inaccurate due to temperature changes. Measurements taken at one build plate and nozzle temperature range will vary from measurements taken at another. Even changing the nozzle temp causes variations. The bed mesh probing is performed at 140C nozzle temp, yet no one prints at that temp. The difference in the distance reading from a stable 60C bed to a nozzle at 140C vs 220C was 0.03mm. Unfortunately, there's no way to change the 140C nozzle bed mesh probing temp from Fluidd interface, it is in the firmware. Combine that with variations in the build plate height if the build plate is not fully preheated, and the initial layer height offset can easily be off by 0.05 to 0.1mm.

One solution that I would like to try is adjusting the [probe] values in the printer.cfg file. These are the default settings:



x_offset: -24.25

y_offset: 20.45

z_offset: 0.0

speed: 10.0

samples: 2

samples_result: median

sample_retract_dist: 3.0

samples_tolerance: 0.1

samples_tolerance_retries: 1

The default number of samples is 2. That means it takes 2 readings and averages them. Taking more than 2 readings (3-4 is a good starting point) and averaging will give a more consistent distance value. The sample tolerance is 0.1, which means that the sample values can be within 0.1mm of each other, which I believe is too much.

"If the results of the test show a range value that is greater than 25 microns (.025mm) then the probe does not have sufficient accuracy for typical bed leveling procedures. "

Therefore the probe sample_tolerance should be smaller than 0.025, otherwise it should retry the sampling. The sample_tolerance_retries should be increased to 3.

"It may be possible to tune the probe speed and/or probe start height to improve the repeatability of the probe."

Therefore the sample speed should be reduced from 10mm/s to a slower speed, like 5mm/s.

Slowing down the z-offset calibration is going to cause an insignificant delay compared to having a much more accurate z height.


The Elegoo Neptune 4 series of printers has ethernet connection, USB, and micro sd card slot, but no WiFi.

The easiest solution to making the printer wireless is to use a WiFi bridge. This WiFi bridge is conveniently powered from a USB port, therefore it can be powered from the USB port on the Neptune 4 printer. No extra cables or power adapters needed!

Watch the video to see how to add the WIFI bridge and how to setup the wireless access:

Rail Wipers

The linear rails on which the metal rollers roll need a light coating of grease. Over time, the wheels will compress dust and debris onto the rails, and the rails need to be cleaned and greased again. A felt wiper will keep the rail greased and clean it off at the same time, keeping the printer running smoother, and reducing maintenance.

I will design a custom 3D-printed part that holds an appropriate-sized felt washer in place against the rail. The felt washer needs to be cut in half because only half of the diameter of the rail needs to be wiped.

Air Filter

I designed a HEPA + Activated Carbon air filter to remove the particulates and VOC from 3D printing and improve air quality. Read more about it here, and how to print your own.


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