Assembling the Ecksbot 3D printer: Part 2

And I'm back. This post, continuing on Part 1 of this series, details the rest of my Ecksbot's assembly process. I ended off last time with the printer only partly assembled, so the first entry for this post shows me assembling the rest of the mechanical parts. I'll then dive into some soldering and wiring and in the end the assembled printer will resemble an awesome mixture of mechatronic majesty (or madness?)

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

Assembling the Ecksbot 3D printer: Part 1

Hi everyone.

I'm a bit angry with myself for having let two months go by before writing this post (as opposed to the two weeks I promised in my previous post), but hey, it's not like I have kept the world waiting. I have had all of 130 blog views since I started the blog, of which about a hundred would be me excitedly reading my first post over and over again. So let's get this thing trending by posting some more awesome technical content for engineers...(ok, that sounded better in my head).

The last couple of months I have been scraping off a few hours here and there, taking the time to assemble a very interesting piece of equipment that has brought me everything from immense joy to a "hit-the-wall-with-my-face" type of frustration. Through this process I have learnt a great many things and I would like to share this with those of you who care for the ways of the 3D printer.

The Ecksbot-ZA v4.0 RepRap 3D printer is a South African flavour (with a lot of handy improvements) of the RepRap Ecksbot, which according to RepRapWiki is a "sturdier and sleeker derivative of the Prusa 2". It has a 180mm x 180mm heated bed build plate and an all-metal hotend (with PTFE liner) which takes 1.75mm diameter filament from the extruder side and melts it down to the 0.4mm diameter of the hotend nozzle. The kit came with everything necessary to assemble the printer according to the assembly instructions available at the OpenHardware Wiki page. Some insights were also derived from the Eckertech site, while the OpenHardware forum helped immensely.

When I started off with this project I decided to document my ventures as much as possible and to this end I recorded the whole assembly process, also taking a fair amount of photos at critical points. The assembly process is divided up into different sections (based on the instructions for the different subsections of the printer) and I have created some videos demonstrating these sections below. The videos do not have the greatest of quality, I apologise for that, but the photos are pretty cool. View them in this folder for a more detailed "assembly guide in colour".

Step 1: Assembling the vertices

I really hadn't ever heard the word "vertex" used in the context of a 3D printer, so this started off in an interesting way. The vertices are the triangular supports with the four feet upon which the whole 3D printer rests and which gives it its sturdiness. Here it was important to ensure (to as high an accuracy as one can manage with these human hands) that both vertices are equilateral triangles, so the ruler and callipers came in handy. The vertex assembly is shown in the video below.

Step 2: Assembling the frame

The next step was to assemble the main printer frame using the vertices from the previous step. Again, for printer stability and sturdiness, it was essential to have equal measurements on corresponding parts on opposite sides of the printer - this can be seen as a requirement for every step of this whole assembly process. The video below shows the printer frame assembly.

Step 3: Assembling the X-axis

This axis is responsible for the left/right movement of the hotend/extruder combo (if you look at the printer from the point of view that the photo shows at the end of the video above). It is driven by a single stepper motor and belt system and it carries the hotend to where it should be in the X-plane. Of importance here is to align the pulleys (for the Z-axis movement guide) as carefully as possible, which looks inherently improbable due to the fact that cable ties are used. But it actually works quite well. Also, don't make the belt too stiff or give it too much slack, as both can cause printing problems. The belts are strengthened with stainless steel wires internally, so they shouldn't really stretch. See the video of this section below.

Step 4: Assembling the Y-axis

The Y-axis carries the aluminium frame, the headed bed, the aluminium printing surface and the eventual 3D printed object in the front-to-back plane (as viewed according to the convention explained above). Like the X-axis, it is also driven by a stepper motor and pulley system. The stiffness of the belt is not extremely important from the start here, as the Y-motor is mounted on a bracket that one can adjust to change the belt stiffness (kudos to whoever made this adjustment to the design). In the case of the Ecksbot-ZA v4.0, the Y-motor mounting bracket is an aluminium part, as opposed to the older versions where it was a 3D printed part. This was to increase stability, or so I assume (it might have been for the fun of it, really, who am I to judge?). See the assembly video below.

Step 5: to be continued

You will have to wait a bit for this one. It might be because I think the post is getting too long, or it might be because I haven't edited the rest of the videos yet. Whatever the reason, you'll at least have something to look forward to soon. And when I say soon, I mean soon as in not two months. More like two... ok let's not make promises.

Cheers!