Step 5: Assembling the Z-axis
This is quite an important step where a fair amount of delicacy is needed, as the Z-axis accuracy influences the resolution (a.k.a. step size, a.k.a. layer thickness) at which your printer will eventually print. Be sure to align everything thoroughly (use your calliper and ruler with abundance) and also be sure not to over-tension the Z-axis coupler pieces when fixing the Z-motors to the threaded Z-axis rods (this led to a nail-biting experience that I'll expand on later). See the Z-axis assembly video below:
Step 6: Solder some stuff (a lot of stuff actually)
This is one of the important aspects to consider before getting yourself into the whirlpool of building a 3D printer (a nice whirlpool, though, not the ones you drown and die in): do you have the necessary electronics skills or the preferred amount of professional curiosity to be able to navigate the non-mechanical side of things? Personally, I don't really think something is interesting enough if you can't induce a potential difference across it's boundaries in order to make some electrons move, so this was my kind of thing. But if it isn't, know that you will have to do some reading and exercise some dedication. The mechanical printer assembly was quite straightforward with enough support and instructions to guide a standard hobbyist through the process, but the electronics part wasn't really an exercise in spoon feeding. See the two videos (Electronics Part 1 and Part 2) below, which is followed by a summary of the videos' content.
With the hotend construction I used a thick wire gauge for the thermistor, which wasn't necessary as the thermistor doesn't really draw a worthy amount of current. (And yes, I used my wife's hair drier in the absence of a heat gun). The thick wire does come in handy with the heatbed soldering though, as this part will draw strong current when it's heated during printing (above 100°C when printing with ABS). The hotend comes with pre-drilled holes in which to mount the resistor element and the thermistor, although I had to drill the thermistor hole a bit bigger so that the glass encapsulated thermistor could fit snugly. The end-stops are wired normally open (NO) and the soldering of the stepper motor drivers is pretty straightforward.
The second video picks up where the first one left off by showing how I finished the heatbed soldering. The thermistor fits into the hole in the centre of the heatbed and I used Kapton tape to stick the wires to the bottom of the heatbed. When modifying the standard ATX power supply it is important that you wire as many yellow wires (+12V) and as many black wires (GND) together as you can (respectively, that is). This will supply current to the whole printer and therefore you need a thick gauge. Also don't forget to solder the green wire to a black one, this is used by the ATX power supply as a kind of soft switch internally. If the green wire isn't grounded, the power supply won't switch on. The hotend cooling fan bracket (supplied with the printer kit) does have 4 holes for screws to fasten the fan, but I was a bit lazy so I just used superglue.
Step 7: The final assembly
The rest of the assembly entailed fitting all of the electronic parts to the already assembled mechanical printer, most of which is shown in the video below. The printbed is mounted, the whole extruder setup is assembled and mounted, and the three limit switches are mounted at the correct spots.
The trickiest part of this step was getting the extruder mounted rigidly and accurately. Assembling the extruder and stepper motor combination wasn't too bad, but using the supplied brackets to connect it to the hotend and fixing this whole sub-assembly to the X-carriage took quite a while. Not all of the holes aligned as they should have and the fan and its bracket seemed to press hard against the bottom of the X-carriage, causing the hotend to lean slightly off-centre and not perpendicular to the printbed. Through trying to make everything fit (read forcing it to fit) I cracked off a piece of the fan bracket and I ended up using a cable tie to keep it fixed to the hotend. The trick is to realise that this whole process is DIY, so if something doesn't make sense and you can use your common sense and some form of expertise to figure out another way to do it, why not try it? If you totally screw it up you'll know that you were wrong :) that's how we learn. Luckily I didn't screw it up totally, the printer has been printing nicely ever since - cable tie and all.
What is not shown in the video above is me wiring all the stepper motors and connecting the other ends of all the wires to the control board. My footage for this part was just not nice enough and I thought I could better explain it with the use of diagrams, something that I lacked when I was building the printer. It might be that there are so many custom versions of RepRap printers out there that it gets hard to standardise on specific wiring diagrams, or it may be that someone just hasn't had the time to sit down and draw a diagram specific to the Ecksbot-ZA. Whatever the case, I am still planning to draw an all-encompassing wiring diagram that I unfortunately I haven't gotten to yet. I'll probably do it sometime before I die, so keep watching this space.
So there you have it, people: an assembled Ecksbot-ZA v4.0. Be on the look out for my next blog post about setting up the printer's firmware and software and doing the first print!
S
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