Geeetech A20M Review: A Large 3D Printer

Geee, what a printer! And it mixes colors?!
Ash Ash (362)
Our rating: 4/5

This is the Geeetech A20M large scale 3D printer. It comes with loads of cool features, extra goodies, and exciting end results. It features a heated glass bed and even supports multiple filaments.

Are you looking for a new 3D printer? It's time to check out the A20M — this printer is not one to be looked over!

Feature Spec
Build volume 255 x 255 x 255 mm
Filament types PLA, PETG, ABS, HIPS, PVA, Wood Filled
Filament diameter 1.75mm
Nozzle diameter 0.4mm
Construction Aluminum Alloy
Extruder type Bowden
Heated bed Yes
Weight 19.4 lb
Dimensions 17.4" x 17.6" x 18.9"
Price Under $400 on GearBest


  • Big build volume
  • Excellent fine detail quality
  • Multiple filament support
  • One unit


  • Bed wobble on delivery
  • Difficult to adjust Y-Axis wheel alignment
Geeetech A20M 3D printer ×1

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The Geeetech A20M arrives very well packed in a styrofoam bed. They provide a few extra tools to go along with the printer, along with a set of instructions to get started. I didn't have any problems with shipping and everything arrived in great condition.

In the box

  • Geeetech A20M 3D printer
  • Gantry frame
  • Bottom frame
  • 2 Extruder motors
  • Ejector Nozzle
  • 2 Filament detectors
  • 2 Filament brackets
  • Power cord
  • SD card
  • 2 Wrenches
  • 2 Filament samples
  • USB cable
  • Cable ties
  • Screws
  • Mouse pad
Assembly and setup

The assembly process looked simple on paper, but was much harder to pull off in real life. I highly recommend a second pair of hands to help when assembling the gantry frame to the base. Beyond the awkward logistics of holding everything in place, the printer came together without much hassle.

The biggest problem came when it was time to level the bed. There was a serious bed issue—making it nearly impossible to level. To solve this issue, I removed the bed and tightened the Y-Axis wheels. After some adjustment, the bed glides without a wobble.


I really appreciate the all-in-one construction of the A20M. There's no separate box for the power supply or main screen, everything is assembled into one unit. The frame, constructed using aluminum, is very sturdy.

If one area could be improved, it would be a redesign of the components underneath the bed. It's very difficult to reach the Y-Axis wheels. Easing that access would make the adjustment process easier.

Build quality

The final build feels very high quality–it's sturdy and doesn't have any extra wobble when printing. The metal frame is has a black matte finish and even comes with some decorative white stripes. I really appreciate having the power supply and electrical components housed in one box under the bed.

Motion system

The biggest problem you'll have with the motion system involves the Y-Axis wheel system. If the adjustments are too loose, the bed wobbles. If the adjustments are too tight, the bed can't move. The X and Z movements, however, present no issues and have delivered some impressive end results.

Bed features

I love the heated bed! It heats very quickly and serves its purpose well. While the bed is made of glass, there is a protective layer on top which leaves a pattern imprinted on everything you print. It's impossible to flip the bed for a smooth glass finish.

Bowden extruder

The printer supports multiple filaments through a bowden extrusion system. You can use a wide variety of filaments 1.75mm in diameter. The filament system feeds to one 4mm extruder nozzle. If you're after a printer with dual filament support, this is definitely a feature you don't want to overlook.

When it comes to 3D printing, safety features can be a huge deciding factor. No one wants a printer that overheats or melts your final prints. The A20M tackles those concerns: when your 3D printed item is finished, the nozzle removes itself and moves away from the item to immediately cool down.


Printing on the A20M is exciting! The bed is huge and the detail quality is impeccable. The trick, as always, seems to be dialing in the best settings. It supports so many types of filaments PLA, PETG, ABS, and more. If that wasn't enough, you can use two spools at once for dual color printing.

Print quality

The print quality of the A20M is surprisingly intricate. From big prints to teeny projects, this printer can make some beautiful things with seriously fine details. Compared to my previous review of the Alfawise U20, the detail quality of the A20M is definitely superior.

The example picture shows the printed head of Robotica, a doll created by Shira. You can see thin design lines, eye details, and even tiny dimples in her cheeks.

Print volume

The bed size for this printer is huge! It comes with a build volume of 255 x 255 x 255 mm. You can make some big things using the A20M, perfect for big projects. There are bigger printers on the market, but you'll find this build space to be relatively flexible for most projects.


The interface takes a little getting used to. The LCD screen is controlled using a knob button. Finding the feature you need isn't always intuitive, but it's something you can master within a few minutes. I appreciate the location and ultimately it does give you all of the basic controls you would expect like leveling tools and extruder settings.


Prints can be sliced using Cura and drop easily onto your SD for printing. You don't need anything extra to get started—just find some stl files, make some gcodes, and boot up the A20M to get started.

Loading prints

The A20M features an SD port next to the LCD screen. It's very easy to load prints into the A20. Using a computer, drag and drop the gcode files onto your SD card. With the card in the printer, select the file you want to print on the screen.

Filament types

It's a fun printer to experiment with. You can use TONS of different filament types with this printer. It supports: PLA, PETG, ABS, HIPS, PVA, and even wood filled filament! Most of my A20M experience so far has been with PLA.

Filament mixing

The coolest feature of the A20M is the super versatile color mixing abilities. The printer comes with software to slowly (or abruptly) transition between two filaments of your choosing. Using the LCD display, you can adjust what level the transition begins and how much of each filament to push through. It takes a little bit of tinkering as there are no instructions provided covering this process. But with a little patience, you can really take advantage of the mix settings to make some beautiful prints.


Overall this is a great printer! The print quality is wonderful and definitely worth a closer look. Compared to other 3D printers on the market, it is not the most affordable. Whether or not this printer is worth the investment depends on your budget and what kind of specs you want out of a 3D printer.

If you're interested in other large 3D printers, check out my CZ-300 review!

A sleek printer for large scale printing.
Ash Ash (362)
45 minutes

The Crazy3DPrint CZ-300 is a very large 3D printer with a bed volume size of 300 x 300 x 300mm. When everything is working just right, it can create some really detailed final prints.