Prusa I3A Plus

Prusa I3A Plus Review and Assembly Tips

In the past, I tested several 3D printers models in the range for personal use, i.e.the classic desktop 3D printers. Thanks to that experience, I could to see their different mechanical designs and solutions (from XYZ printer to Rep Rap, Prusa, Robox etc.) so I eventually got my personal opinion on what are the essential characteristics of a Desktop 3D printer.

I refer to those tools that are mostly for personal use and small production. Of course, that should not limit the ability of the printer to work in a stable manner for a prolonged time. Another key factor should be the replicability of the printing process. As a matter of fact, a 3D printer is a reproduction machine and we should be able to make multiple copies of the same design without any meaningful variations between the first and the last piece.


Recently, I had the chance to use the latest model manufactured by Geeetech, i.e. the 3D Printer Prusa I3A Plus. They launched this new version on the market focusing on the most evident innovation: the external control box that embeds all the electronics; Power unit, front panel LCD and rotating switch, SD Card slot, main board controller and motor controllers, and the switching power unit.

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This solution is very good in order to make things easier for both assembling and using the printer, but there are also other meaningful aspects, maybe not so evident but important as they increase the printing quality and performances; so, I thought to take a look more in depth to this product.

The box contents and the assembly process

What is inside the DIY box? It contains about 12 Kg of pieces, almost all the parts and tools needed to assemble the 3D printer.
As the included tools are just a set of screwdrivers that are not sufficient to complete the assembly, to work without problems you need the following:

  • An optional tester (it may be useful in the final step or to check the wiring in case something goes wrong)
  • A set of Allen keys (minimum M2, M3 and M4)
  • A robust plier to assemble the frame aluminium parts
  • A 17 key for the axes nuts
  • Some neutral vaseline grease
  • An optional caliper or a metallic precise ruler

Assembling the printer is not difficult, but a minimum mechanical experience is a plus especially for the calibration step of the axis parts and motors and the tooth belts tensioning.

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To assemble the printer I saw the instructions in the support material provided by freely downloadable from their site and the videos available in a progressive playlist on Youtube.

The box contents are very well organised; every kind of screw, nut, washer etc. are in a separate numbered plastic bag; this simplifies the assembly also to those who are not familiar with the traditional components nomenclature; there are M3 and M4 screws of different lengths, different kind of nuts, washers etc.

Unfortunately, the manual has quite few images describing the assembly procedure of some parts. Thats limitation is compensated by a complete series of video instructions (but not everybody likes to follow a video while mounting parts); the video how-to shows the instructions for the model I3A (not the Plus version): 90% of the instructions are identical apart from some very intuitive exceptions, but the last part showing the electronic part assembly is totally different.

In this new model, electronics and controller, display and switching power supply are in a separate box while the aluminium main frame supports only a small connector board. It is easier to assembly and more comfortable to use, even if it may create some confusion for a first-time user.

The advantage of having all the controlling parts in a separate box justifies the small effort to understand the differences. Anyway, I think this is a part that Geeetech should update soon.

A look inside the electronics

On the printer main aluminium frame you should only attach a small board that connects the wiring from the parts (i.e. extruder, temperature sensors, heatbed, stepper motors, end stop switches).


On the contrary, the electronic control box is shipped pre-set and pre-assembled, connected to the printer body by two flat cables.
Of course, I opened it.

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The components inside are well organised and with a proper ventilation; the cooling fan is a bit too noisy and a silent fan will be extremely appreciated, especially by the home users launching their printing jobs overnight.

Thanks to the good arrangement inside the box, any troubleshooting or parts replacement are easy. I appreciated the availability of clear PCB references near all connectors and also a good availability of test points. A number of useful LEDs monitor the activity of the device and the signals. As expected, the main board – re-designed by Geeetech – is Arduino-based; experienced users can manage the firmware and hack the board with changes and improvements without any difficulties.

In future, it would be worth reviewing the board firmware display controller. The tool works very well with the Repetier software and Cura (even if I prefer Repetier with the Cura slicing engine), but the wide display has a lot of space that could be used to show more information compared with the current one.


The lack of the firmware installed on the printer (non-blocking) only affecst the display, so as a matter of fact there are not limiting or blocking problems in the system functionality.

The first issue is the auto home function: it works well when launched from the printer menu, but it seems to only be effective on the Z-Axis when launched by the printing script via G-Code.

The second, and quite annoying, issue is that after a while the x, y, z axes positions are not correctly updated on the display.

On the other hand, I appreciated the accuracy of the pre-set pin values on the board. You can start printing after the assembly is finished without trying to see if the steppers sequences are set correctly.

Key Aspects and Strength

It is true that – in theory – it is possible to produce most of the 3D printer components as 3D printed, as well as dramatically reduce the costs of the machine thanks to an extreme simplification. And it is also true that these devices will work fine. Obviously, at least some quality aspects will be impaired.

In this 3D printer, I found a series of concurrent factors (mostly mechanics) that make possible to produce very good printings highlighting the effort to keep pricing at a reasonable budget with a very good level at good printing speed (about 55-60 mm/sec on 2mm thick layers).

Usually, the X-Axis belt lock is a 3D printed component. Here, I saw instead a robust plastic one. That affects the stability and tension of the X-Axis beltand the belt fixing, and the axis calibration and tensioning is extremely simple.


Similar but totally different than the more conventional M4 threaded bar, the Z-Axis driver is a robust and rigid inox threaded screw that offers an incredible accuracy to the nozzle vertical movements. The bronze Z-Axis stepper guides in conjunction with the threaded bar make the vertical movement perfectly stable during the printing.

image11sembly Hints to Make Things Easier and Reliable

When needed, file any aluminium parts that does not fit in place

One of the most interesting aspects of the built structure of the printer is the quality of the frame: solid 4 mm aluminium well-finished and sanded in all the parts. Some parts are difficult to fit together. As they should support the mechanical movement, they need to be extremely stable. Frankly, I prefer spending a few minutes filing and inserting them with the help of a plier than risking any instability of the pieces.

Avoid front and rear parts of the Y-Axis misaligning

The Y-Axis front and the rear plates frame are equipped with four nuts on the horizontal screwed bars. All the nuts lock by rotating in the same direction (clockwise). In order to avoid any misalignments while firmly locking the nuts, you should use two wrenches and close them in a cross pattern. On the right side, keep firm the farthest nut and rotate the inner one using the wrench. Carry out the opposite procedure on the other side for both side plates, front and rear.

Place the main vertical frame in the correct position of the Y-Axis (not in the middle)

Even if it is not indicated in the instruction manual, we should take into account that the vertical frame should be fixed about 2 cm nearer to the Y-Axis motor side relative to the middle of the frame. That is because once the extruder nozzle is fixed in place it is about 2 cm nearer to the Y 0 position (observer side). So, the vertical frame distance should be 22 cm from the front Y-Axis plate and 18 cm from the back.


No grease needed, but…

The bar screws and moving bars do not need any service, because all the sliding parts use linear bearings. But to improve durability (and zero noise) it is better to apply a thin vaseline neutral mechanical grease coat over these parts. Besides, that kind of grease is suitable for plastic sliding parts and you only need a thin coat to get a good result.

Fix the heating bed in place when assembling the printer

Many 3D printers do not use the heating bed to stick the filament. According to me, it would more complex to get good results without a heating bed and that is why I always chose one as part of the 3D printer. One of the most important things to pay attention to in order to avoid any wrong 3D printings is the bed calibration. The heating bed is a PCB (heating unit) on top of which you will attach a 3 mm glass plate where the 3D printing will be built. Placing the heating bed in the right place while assembling the 3D printer makes the difference; just follow these two easy steps:
1. Fit in place the heating bed PCB keeping the four springs at about the centerline of their maximum compression. If when calibrating the bed during the normal usage the springs are too extended, the bed becomes unstable; on the contrary, if they are too compressed it will be difficult to lower the bed during calibration.
2. After assembling the springs more or less at the centerline using a precision (metallic) ruler or – better – a caliper, check that all the four screws keep the heating bed at the same distance from the driving plate.

It is important that you keep the same distance at all the four corners. Using a caliper, carry out the first measurement, then lock the ruler and check the remaining corners as well.

Setup correctly both sides of the Z-Axis drive threaded bars

One of the most influencing aspects impacting the quality of the 3D printing is the correct alignment of the two motors over the drive threaded bars for the Z-Axis. After the Z-Axis mechanics has been more or less set in place, complete the alignment using the most accurate measurement tool you have.

The first 3D print test

The following images shows the first print test launched after the assembly.
Printing conditions:
• Nozzle diameter 0.4 mm
• Print speed 55 mm/s
• Filament Geeetech PLA diameter 1.75 mm black
• Layer thickness 0.2 mm
• Type of support: Brim 5 mm wide
• Extruder temperature: 110C
• Hotbed temperature: 80C
• Adhesion type: glue stick

For a better calibration I always use a micrometric feeler. The optimal distance between the hot surface and the nozzle should be between 0.5 mm and 0.7 mm With the feeler value set to 0.10 mm, calibrate the four corners of the bed until you need to apply a small pressure to insert the 0.10 mm feeler. Then double check with the feeler value set to 0.5; it should fit between the bed and the nozzle without forcing.

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The images below shows the optimal result obtained with the Prusa I3 Aluminium Plus

Product evaluation

With a pricing between 408 and 430 USD depending on the distributor, Geeetech Prusa I3A Plus can be considered a very good desktop 3D printer. Considering the usability and the mechanical quality we may assign a rating of 9/10


The images and screen captures are property of the author, distributed under license CC 3.0 SA-NC-ND

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