Review of the PRUSA I3 EG-1 3D printer (part 4)

Ok, a bit late writing this part 4. I completed the assembly during the week-end with the help of Justin (my second boy):

The next step was the wiring, and man a Prusa design has a lot of wires ! ElectronicGeek, you should really beef-up the documentation regarding how and where to run the cables.

During assembly I had done one mistake in the orientation of the Z motors. The cables have to go out the back:

With the kit comes a nice cable management plastic wrap. There is more than enough but I went overboard and used some of the same stuff that I already had handy. This cable wrap is pretty inexpensive and easy to install (even for a guy that sucks at cable management like me):

Now an other piece of advise for the EG folks. I would suggest that you install crimped terminals on the side of the wires that go to the power supply. Makes for a much more solid connection to the screw terminals:

I only had ring type terminal available but what you want is what they call "spad" terminals:

Now regarding the teminals on the power supply, the label showing the terminal position was a bit shifted on mine which made me do a wrong connection at first:

Once all that was done and that I double checked cables (especially power) it was time to power-up the unit and try to move the axis with the RepetierHost software connected from my laptop to the printer using the supplied USB cable.

That went without much problem, I was able to move X, Y and Z just fine. 

My next test was to check the auto-level sequence. I'm used to this having added a similar induction sensor to my PrintrBot Simple Maker. It's as easy as homing X, Y and Z, and then sending the G29 GCode command. 

That is where I hit an issue... After homing X and Y, the head and induction sensor that is supposed to sense the metal of the bed was way out of the bed:

If I tried homing Z at that point it would NEVER sense metal and would crash when hitting the bottom of the Z threaded rods... You don't want that.

After some investigation I found that my Melzi board was running a Repetier firmware which it's not supposed to be as this printer is supposed to come with the open-source Marlin firmware. Not expecting much before Monday I fired an e-mail to ElectronicGeek support and to my surprise Eric responded a few hours after asking for picture of the display.

Following sending Eric the picture of the display et responded that indeed I had a Melzi board with a Repetier firmware and it was not supposed to be, should never have shipped that way. Unfortunately the only way to reprogram the board was using a USBISP adapter which amongst all the Arduino stuff I have I did not have that... Eric suggested that they ship me a replacement board which was fine with me. They shipped it Monday and I got it today Tuesday. 

During my lunch break I installed the new board and bingo auto-level probing was working. I proceeded with very basic manual bed level and Z-Offset calibration. I was eager to do a first print !

I was really surprised by my first print result, happily surprised:

This is the 50mm calibration angle found here:

That is it for now. My next article will be about doing some Repetier configuration and providing some example config.


  1. Wow a lot more assembly to do on that printer compared to the Zonestar, Glad you managed to get it all together and print something :), I can only compare it to the Zonestar due to that's the only 3D printer I have assembled, I ended up with a few extra screw, nothing missing, also the hotend came fully assembled, and the heated bed came with crimps :) Great Job assembling the printer, looking forward to future reviews :)

    1. I actually like kits like that. You get to know the printer construction very well and it's much easier to troubleshoot after and make mods for it.

      My other printer is a Printrbot Simple Maker. It used to be a 4"x4"x4" build size and upgraded it to a 13"x6"x4" build size with a induction sensor for auto-bed level.

    2. Thanks so much for this blog, it has been helpful as I start assembling my own!

      Mine either doesn't have clear plastic on the Lexan (the other side with brown paper came off easily) or it is VERY hard to detect. I have spent many minutes poking, prodding, scraping, looking for some kind of plastic to lift off the Lexan, and I can't detect anything.

    3. Hi Jay,

      Thanks. There is an other part coming, just need to find time.

      On mine there was just the brown paper on one side after all. No clear plastic on the other side.

  2. any chance you could post some images from the under side. especially the timing belt section...the guides on the website are just awful, and something just seems off on mine. Thx.

    1. I agree highly they really need to improve the guides they offer

    2. Dragonsire, take a look at these:

  3. nice thx. That's what i basically have. I have it built, except for the electrical, which i will do later tonight.

    I ordered the autolevel, them semm to have sent me the wrong package...the setup without it. So I got 2 of the larger limit switches.

    NOw I have noticed the diagrams show the limit switch has a plug that should be empty pin/yellow/black going into the control board, but the plugs I received has empty pin/black/yellow (both) though. Were yours the same as the diagrams?

    1. I had 2 big ones (wired the same) and one smaller one. Used 1 of the big one for the Y limit and the smaller for the X limit. I have the Z probe so I did not use the second larger limit switch.

    2. BTW if black and yellow are reversed it does not matter. The bottom pin is the common. On the side the pin closest to the arm is the normally-close and the other one is the normally-open.
      What you want is a wire on the common and an other one on the normally-open.

  4. Salut André
    J'ai suivi tes étapes qui mon été très utile afin de complété mon installation. J'ai toutefois un problème de communication entre mon ordinateur et le printer... J'ai installer Arduino afin de mettre a jour ma carte que je crois être mega 2560 , mais aucune connexion... pouvez vous me guider vers une piste de solution... Merci

  5. Bonjour Frederic,

    Je n'ai pas essayer de recompiler le firmware Merlin et de l'uploader sur la carte. Cependant, habituellement il faut utiliser Arduino 1.0.6 plutot que la derniere version pour compiler Merlin.

    Pour la communication, j'imagine que tu est capable do communiquer avec l'imprimante avec Cura, RepetierHost ou autre ?


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