Today I want to share a great review which have some useful tips and tricks on assembly and calibration of Prusa I3 A pro. It's created by @balearicdynamics and thank for his sharings very much!The original page is https://www.element14.com/community/doc ... structions.
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Here is the Content
1、Introduction
2、Unboxing and assembling
2.1、Box and assembly instructions
3、Electronics: a look inside
3.1、What's in the box?
4、Key aspects for quality
4.1、X-Axis belt lock
4.2、Z-Axis threaded drive screw
4.3、Bronze Z-Axis stepper guides
4.4、Print test
5、Pricing and voting
5.1、Voting
6、Appendix: Things useful to know
6.1、Some Aluminium part don't fit. Why?
6.2、Y-Axis front and rear sides misalign when I close the nuts
6.3、Where to fix the mid vertical frame?
6.4、For a better duration of the moving parts
6.5、Fixing the heating bed in place
6.6、Z-Axis: how to setup correctly
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1、Introduction
In past I have tested several 3D printers models in the range for personal use, the classic desktop 3D printers. Having had the possibility to see the different mechanical designs and solutions (from XYZ printer to Rep Rap, Prusa, Robox etc.) I have definitely reached a personal opinion on what should be the essential characteristics of a Desktop 3D printer.
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2、Unboxing and assembling
After ordering what do you receive? A flat box of about 12 Kg weight including almost all the parts and tools needed to assemble the 3D printer. Really the included tools are just a set of screwdrivers not sufficient to complete the assembly; You need also a tester (maybe useful in the final part o to check the cabling if something goes wrong), a set of Allen keys if you like to work better than using the provided tools a plier and a 17 key for the y-axis nuts. Take a look to the work in progress image below
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To assemble the printer I have followed the support material(https://www.geeetech.com/Documents/Prus ... uction.pdf) provided by Geeetech.com freely downloadable from their site and the videos available in a progressive playlist on Youtube(https://www.youtube.com/watch?v=KCKfAqo ... _DPNh3KWgj).
2.1、Box and assembly instructions
I should say that the box content is very well organised; every kind of screw, nut, washer etc are in a separate numbered plastic bag; this simplifies the assembly also to those not used to the traditional components nomenclature; there are different length M3 and M4 screws, different kind of nuts, washers etc.
The limitation of the manual is in the few availability of images describing the assembly procedure of some parts. This limit is compensated by a complete series of video instructions; unfortunately this how-to shows the instructions for the model I3A (not the Plus version). 90% of the instructions are identical with some very intuitive exceptions but the last part showing the electronic assembly is completely different. In this new model the electronics and controller, display and power switch are in a separate box while on the Aluminium printer frame only the connector board should be placed. It is easier but may create some confusion for the first time user.
The advantage having all the controlling parts in a separate box widely justify the small effort to understand the differences. Anyway in my opinoin this is a part that it is the worth Geeetech should update soon.
3、Electronics: a look inside
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The electronic control box is shipped preset and preassembled. Obviously I have opened it. All the components are organised well with a good aeration. It is far from an "untouchable stuff"; any problem that will occur during the use of this 3D printer it is not easy to check the electronics and eventually replace the parts. I have appreciated the availability of the PCB references almost clear for all connectors and test points, including a number of useful LEDs to monitor the activity of the device and the signals. As expected the main board - redesigned by Geeetech - is Arduino based and experienced users can manage the firmware without difficulties. In past I had no difficulty to ask to them for a copy of the sources to make testings and some improvement, adaptions etc.
What I have found it is the case to review in some points is the board firmware. The printer works very well with the Repetier software and Cura (but I prefer Repetier with the Cura slicing engine) but the wide display has a lot of space that can be used to show some more information than those actually shown.
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The first issue is the auto home function: it works well if you launch from the printer menu but seems having only effect on the Z-Axis when it is launched by the printing script via G-Code
The second issue (almost annoying) is that after awhile the x, y, z axes positions are not updated correctly.
What instead I have appreciated is the correctness of the preset pint values on the board. You can start printing after the assembly is finished without trying to see if the steppers sequences are set correctly.
The pictures below shows the box open an running.
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It is true that - at least in theory - it is possible to make 3D printed most of the 3D printer components as well as dramatically reduce the costs with an extreme simplification of the mechanical parts. And it is true that these devices works. But it is obvious that some aspects of the quality are penalised.
In this 3D printer I have found a series of concurrent factors making possible to produce very good printings. It is evident an effort to keep pricing at a reasonable budget reaching a very good level at good printing speed (about 55-60 mm/sec on 2mm thick layers)
4.1、X-Axis belt lock
Usually it is a 3D printer component while in this case I see it is a robust plastic one. It influences the stability and tension of the X-Axis belt and the belt fixing and registration is extremely simple.
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Similar but totally different than the more conventional M4 threaded bar. It is a robust and rigid inox threaded screw that gives an incredible precision to the vertical movements of the nozzle.
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This component in conjunction with the vertical threaded bar make the Z-Axis perfectly stable while printing.
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The images below shows a print test as it was done and removed from the heating bed.
Printing conditions:
Nozzle diameter 0.4 mm
Print speed 55 mm/s
FIlament Geeetech PLA diameter 1.75 mm
Layer thickness 0.2 mm
Type of support: Brim 5 mm wide
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This printer is sold on the market at a official price (Geeetech.com site) of 428,00$
Shipment and assistance are delivered through several stores in Germany, UK and USA
The printer will be delivered in less than a week via DHL worldwide
The post-sales assistance is done by China. I had an issue with their products and it was possible to solve them in no more than two days.
5.1、Voting
After testing and using the printer, assembling and inspecting it with some more experience with previous Geeetech models I will give to this tool a global rating of 9/10 Below the details:
• Mechanics and moving hardware: 9.5 (something can be done better)
• Electronics and wiring: 9
• Easy to assemble: 8.5
• Software compatibility: 10 (works fine with Repetier and Cura and other tools on both Windows 7, Windows 10, OSX)
• Firmware: 8
• Price: as usually, we pay what we get. Some of the materials used are top quality and they cost more. Better if the price will be nearest to 400$. Free shipment will be appreciated.
6、Appendix: Things useful to know
Also following in the best way the assembly instructions there are some details that it is better to know before (while mounting the mechanics) instead discover by yourself while using the printer. These are just some tips to take in account; all can be regulated in every moment and as far as I know these are also useful on the other Prusa models from Geetech and other providers.
6.1、Some Aluminium part don't fit. Why?
Applicable to all the Aluminium Geeetech series of 3D printers and other providers distributing 3D printers with Aluminium frame
One of the most interesting aspects of the build structure of these printers in my opinion is the quality of the metal: solid Aluminium well refined in all the parts and sanded as a nice finiture. Due the exact measure cutting I found some parts are difficult to fit; as these parts should support mechanical movement and should be extremely stable frankly I prefer to spend some minutes filing and inserting it with the help of a clamp than having the piece unstable. The images below shows what I have done to the z-axis stepper motors supports inserted in the main vertical frame.
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This seems a stupid problem but it happens. We should take in account that when we lock the four nuts on the horizontal screwed bars there are two nuts on the right side and two on the left. But all the nuts closes rotating in the same direction (clockwise). To avoid misalignment while firmly closing the nuts you should use two keys and close them crossed. Not only but on the right side keep firm the most external nut and rotate with the key the internal one. Do the opposite to the other side.
Conclusion: the rotating (locking) nut should always be the one that has no influence on the locked plate position. The same is valid for the middle group locking the vertical frame of the printer.
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6.3、Where to fix the mid vertical frame?
It is not mentioned in the instruction manual but we should consider that the vertical frame should be fixed not in the middle of the Y-Axis frame (as intuitively seems obvious) but 2 cm nearest to the Y-Axis motor side. The reason is that the extruder nozzle when fixed in place is nearest to the y 0 position of about 2 cm. So the vertical frame distance should be 22 cm from the front Y-Axis plate and 18 from the back.
6.4、For a better duration of the moving parts
The bar screws and moving bars are not required to be treated as all the sliding parts uses linear bearings. I have experienced instead that for a better duration (and zero noise) it is the case to paint a thick Vaseline neutral mechanical grease. I have found this product investigating what is that white grease that last for years on the moving parts of the modern ink jet printers. It is sufficient a very thick paint to get a good result.
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Despite there are many 3D printers that does not use the heating bed to stick the filament it is more complex getting good results without it; this is the reason that I always chose the heating bed included in the 3D printer. I see that there are lot of good - and
some reliable - methods to stick the filament cold but I have experienced that with the heating bed it is incredibly easier to make good 3D printings, also large pieces and the presence of this small add-on (the Prusa original heating bed has a price of about 10-12$) is unvaluable.
One of the most important things to pay attention to avoid wrong 3D printings is just the bed calibration. Take in account that the heating bed is a PCB (heating) on top of which you will fix a 3 mm glass plate that is where the 3D printing will be built.
Calibration needs to be done almost frequently and it is an operation that it is not difficult to experience in few time. Placing the heat bed in the right place while assembling the 3D printer can make the difference; it is sufficient to follow these two easy steps:
1. Fit in place the heating bed red PCB keeping the four spring in about the middle of their maximum compression. When calibrating if the springs are too high the bed become unstable while if they are too compressed you will have difficulties lowering the bed during calibration.
2. After you have put the springs in an average identical position using a precision (metallic) ruler or - better - a caliper check that all the four screws keeps the heating bed at the same distance.
I have verified that the optimal distance of the heating bed from the Y-Axis driving plate is about 15 mm. It is not important that the distance is exact but it is important that you keep the same at all the four corners as much as possible. With the caliper, to do this make the first measure then lock the ruler and check the remaining corners as well.
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One of the most influencing aspect for the quality of the 3D printing is the correct alignment of the couple of motor screw drivers for the z-Axis. Following a similar method as explained in the previous point, after the Z-Axis mechanic has been set in place in an average way complete the alignment of the two motor screws using the most precise measure tool you have. Only if the two screws are perfectly aligned your tool will work perfectly.
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