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General information collated into the most often asked questions and answers.
NOT an official Anycubic-operated forum; just customers discussing their machines.

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Anycubic Mega i3 Pro Limit Switch.

by Michael1950

Mega i3 Pro Z axis Limit switch. Ihad to replace the z axis limit switch on my Anycubic Mega i3 Pro, switch now working but shuts off power when activated for homing, have adjusted both switches but still shouts down printer. Any suggestions please.
Mike B.

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Anycubic i3 mega - Yet another Z axis anti wobble stablizer bear

by Thr333DDD


Just wanted to share the new design. Feedback is welcomed.

Anycubic i3 mega - Yet another Z axis anti wobble stablizer bearing leadscrew
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Thread to document and discuss the various i3 mega's firmware.

This thread will almost certainly occasionally overlap with the HARDWARE thread:

Marlin 1.1.6 with original Anycubic i3 Mega display support

Official firmware release
Usefulness unverified.

Everything else under this line was written before functional firmware was available, so is likely to be incorrect.

"I just got my printer and I want to flash the firmware to be sure it's the latest"
No. Flashing the i3 mega is not as easy as it should be. Just go and print stuff.


  • YES. The official sourcecode is "available" and you can modify it.

    • However simple things like the age of the files means that syntax will conflict with newer IDE's. Simple anomalies like trigorilla.h being referenced when the file is actually called Trigorilla.h (uppercase/lowercase discrepancy), and Configuration.h still using the standard LCD2004 (REPRAP_DISCOUNT_SMART_CONTROLLER) do not inspire confidence that it is actually the source. It almost certainly is not, but rather a hobbled-together collection of old code from previous printers that omits any reference to the i3 megas TFT.
    • Unofficial sourcecode is available. See note #1 at bottom
  • NO. The official source will not compile as-is.

    • It will give variable name errors unless you
    • 1) use the old Arduino IDE (at the time of writing this may no longer be possible)
    • or 2) you make some copy/paste edits to the source code to update the variable names to the new IDE requirements.
    • or 3) Manually go through a copy of the new code and intelligently insert values relevant from the old code, or that you know to be correct. This method is not difficult, but it does require an understanding of what you are doing. Comparing the 'official' mega sourcecode from Configuration.h against the new Marlin Configuration.h will help you to begin understanding.
  • YES. A compiled .hex is available for the i3 mega and i3 ultrabase.

    • So if you should manage to kill your firmware you "should* be able to reflash it from the pre-compiled hex.
    • One of these .hex files includes the dual z-endstop modification. So if your levels are always mysteriously wrong, and nozzle crashing into he bed on first print of the day, then you should consider this.
  • NO. We do not have access to the firmware for the touchscreen. (which is separate to the printer firmware)

    • In theory you can modify Marlin and not alter the touchscreen at all. However there is no known option for the anycubic TFT in marlin firmware, so you therefore cannot select a compatible display option in marlin, and therefore eithe rlose the display entirely, or need to (physically and in firmware) substitute another known display type.
    • REQUEST: Someone please try all of the other available Marlin options for LCD screens, to test if the anycubic screen is in any way functional under a similar driver.
  • YES. You can use a LCD2004 or 12864, or any commercial TFT like the MKS32

  • YES. If you are working on accessing or reverse engineering the TFT operations then you are our hero and we love you. Please keep us updated on any progress or task delegation requests.

  • NOTE: Anycubic seem to neglect to adjust the version number on their hex releases, so don't be surprised if the 'new' hex you flash has the same version number as the original one.
    • The above assumption needs confirmation, but I have seen it mentioned a couple of times now, so to the best of my knowledge it is correct.
    • REQUEST: Someome please test and confirm:
    • hex [list it's filename and where it came from]
    • has what purpose [list it's supposed functionality ie: dual-z-sensor, ultrabase version, original inductive sensor version, etc]
    • displays what version numbers

Bought to my attention by Matej Zubčić on Facebook:

Basic firmware info:


pkochubey's host of the hex:

Arduino IDE (compile the sourcecode and upload the hex to printer):

  • How do I compile sourcecode:

    • get the Arduino IDE
    • get the source code (but becasue there is no really definitive package, and you will have to edit whatever you get anyway, you may as well just get the latest Marlin source and - using logic - modify it to be similar to whatever source code appears to be most like the i3 mega. The previous 'anycubic prusa i3' model's soure is probably most appropriate and available.
    • open the .ino file found within the source code with Arduino IDE
    • plug your computer into your arduino board via USB
    • check that the iDE is set to a mega 2560 type board
    • check that the iDE is set to the correct com port (the printer wil appear as one when it's connected)
    • Ctrl U
  • How do I decompile/edit the .hex? :
    • You don't.


  • 1 : If you know how to modify firmware code, and are prepared to use your brain to figure out if this is entirely appropriate or not there is this:
    The standard machine does not use one driver for the two Z nemas - so there are some obvious modifications, but this source is likely to be about as close to standard with improvements as any.
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Anycubic i3 Mega hot-end and hotbed spots heating at mid print

by I_Acosta

I have this i3mega for a few years now, this week it start showing this problem in some prints where pasts 10 to 20 mins the hot-bet and hot-end stop heating, temps start drooping showing so in the printer display and on the cura software.

Firmware is the original from fabric
Slicer: Ultimaker Cura 4.12
Printing with usb cable direct from pc

Any ideas of what could by causing this issue?

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Weird jump on Y Axis while Printing

by PhiBu

Hi all,

I´m fairly new with 3d Printing and the i3 mega (ultrabase Version) is my first printer.
I´ve had some Issues from the start, but some i was able to fix by myself.

So currently i´m having a weird Issue where the Print somehow messes up on the Y-Axis.
The First 0,5-1cm of the print is printing fine, but then the Y-Axis fucks up for some weird reason.
It´s like the Anycubic is "forgetting" where the center is.

I don´t know how to explain further, but please see pictures.
The model litself is sticking well to the bed, so the part moving is not the issue.

If you have any idea, please help :)


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Pause at Height with Prusaslicer

by harlekin1247

I use my Anycubic i 3 mega and Prusaslicer 2.3.1 + win 64. It work wery well but I have a problem to which I cannot find a solution. If i insert a Pause at height, m 601 code, the printer does not pause and prints till the end of the printing process.
If i use Cura 4.10.0 the printer pauses at the height i have set.
Do you have any suggestions to solve this problem?
Thanks in advance

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Service support from Anycubic

by rdate

I am having an extreme delay in part replacement from Anycubic. Still waiting for the hotbed surface now it is almost 1.5 years.

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Great start g code and end g code for anycubic i3 mega

by brunoosti

I'de like to share this. I've tuned it to purge the nozzle in a way it starts printing the actual print as soon as the nozzle touches the bed, with no ooze or derby on the tip. Experiment yourselves to see if it fits your needs:


G21 ; metric values
G90 ; absolute positioning
M82 ; set extruder to absolute mode
M107 ; start with the fans off
G28 X0 Y0 ; move X/Y to min endstops
G28 Z0 ; move Z to min endstops
M501 ; restore epron settings
M420 S1 ; apply bed leve mesh (if you updated the firmware)
M106 S255 ; fan on
G0 Z0.2 F1800 ; move nozzle to print position
G92 E0 ; specify current extruder position as zero
G1 X190 E50 F1200 ; extrude a line in front of the printer
G92 E0 ; specify current extruder position as zero
G0 Z20 F6000 ; move head up
G1 E-6 F2400 ; retract
G04 S2 ; wait 2s
G0 X0 F6000 ; wipe from oozed filament
G1 E-1 F2400 ; undo some of the retraction to avoid oozing
G1 F6000 ; set travel speed to move to start printing point
M117 Printing...


M104 S0 ; turn off extruder
M140 S0 ; turn off bed
M84 ; disable motors
M107 ; fans off
G91 ; relative positioning
G1 E-6 F2400 ; retract the filament
G1 Z+0.5 ;X-20 Y-20 F7200 ; wipe from model
G28 X0 ;Y0 ; move X/Y to min endstops
G1 Y180 F2000 ;
M84 ; steppers off
M300 P300 S4000

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Print Bed Flatness

by Cativo

A common issue with most 3D printers is maintaining print bed flatness. Aside from adjusting the flatness with the four corner thumb screws, planarity is also critical. Print bed warpage is hard to correct, and that's one reason why some people mod their printers with glass beds (not to mention adhesion issues).

I performed that mod on my Mega since I had some flatness issues, and I wanted to use smaller nozzles, which required critical flatness (thanks BETLOG for the heads up!). What I found was interesting so I thought I would share my experience.
I ended up buying this glass and thermal pad:

However, after installing it and performing the flatness adjustment, it too seemed just as warped as the original aluminum bed. I could get all four corners adjusted perfectly, but the center was almost .2mm higher. What gives? Some people were reporting that their glass was coming in warped from the supplier, so I checked mine with an accurate straight edge and it was dead on flat, so where is the warpage coming from? I thought maybe the paper clips I used to hold down the glass was warping it, but I also checked it installed and it showed perfect flatness, so how is the center rising up .2mm?

As it turns out, there was a bend in the two y-axis shafts, which I found odd since they are made from high precision steel. Well what I discovered was the shafts on their own were pretty straight (after removing them), but what was causing them to bow were the end mounts. The end mounts don't have a very large mounting surface so they can easily tilt if there are any surface variations in the sheet metal cover that they are mounted to, and in fact, they mount very close to the edge where there is a bend radius. You can tell if the alignment of the end mounts are off by loosening the four set screws (one on each side of both ends) and attempting to slide the shaft back and forth. If everything is aligned well, they should easily slide and rotate. Mine didn't. What I did to fix the problem was loosen the end mount attachment fasteners (to get the jammed shafts to slide out) and take a 5/16th drill bit (slightly smaller than the shaft diameter) and insert the smooth end into the end mount hole. Carefully use the drill bit to bend the sheet metal slightly, correcting the tilt. It will take several attempts to bend and check free movement of the shafts. Here is a picture of what I'm talking about (exaggerated in Photoshop to illustrate the tilt):

Once everything was straight, the bed was much flatter and I could successfully print at .05 layer thickness. I think the Anycubic design team should consider widening the end mount footprint so that it would be less likely to tilt with small surface variations, or check for free rotation after they are mounted. I hope this helps anyone with print bed flatness issues!

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