The RepRap Ecksbot 3D printer - first print and lessons learnt

I've completed quite a few prints since setting up my printer with the required software and completing all the hardware checks that I described in my previous post, so it's probably a good idea to write down some thoughts before they disappear into the cold and dark recesses of my brain.

 Some good reads before you hook up and start printing:

• "Getting started and first print" - from the OpenHardware Wiki.
• "First Print" - from the more up to date OpenHardware Help site.
• Obviously there are many more, but these were sufficient for me to get started with my Ecksbos-ZA.

My first roll of filament was red PLA, so many of the pictures and videos to come will be filled with that colour. PLA is a very standard filament type to start with, as it has a low printing temperature and generally does not require the printbed to be heated. All in all it is less finicky than other filaments, or at least it's like that if you are a beginner, so I'd recommend starting with PLA. I know I concentrated on "final" checks in my previous post, but there definitely are some final final checks worth looking into before pressing the "print" button:

• Cover your aluminium printing surface (the one already covered in the yellow Kapton tape) with blue masking tape (Sellotape brand). I don't know why this type specifically, but it was recommended to me and it works extremely well with PLA, so I'll stick with it (I bet you didn't see that one coming...). For ABS, the experts suggest using ABS juice (a mixture of one part ABS filament and one part acetone spread over your printing bed). I haven't printed with ABS yet and haven't had a chance to try out the juice, but I'll post about it when I do.

Blue masking tape (Sellotape brand)

• It might seem obvious, but don't forget to use the provided paper clips to keep the aluminium printing surface fixed to the heated bed. They are not just there for in case, they are definitely needed to keep your printing surface stationary relative to the Y-axis and through that to ensure a good printing quality. (I forgot the clips more than once and had the same amount of screwed up prints).

For my first print I used this calibration cube design available on Thingiverse. I sliced it with Slic3r using these settings available from the OpenHardware github repository (I should start using github more, I'm realising more and more how extremely useful it is) and printed with red PLA (go figure) at 190°C hotend temperature and the heatedbed at room temperature. For small to medium prints it should be fine if the heatbed is switched off, but for bigger prints having the heatbed at about 50 or 60°C is recommended (for PLA).

So without further ado, here is a video excerpt from my first print and a photo of the printed cube (whoop whoop!):

The printed calibration cube (my first print)

The jet engine you hear in the background (or foreground, more likely) is the sub-standard hotend cooling fan I had on initially. After the first print I replaced it with a slightly more expensive one and the improvement was immediate and effective - no more runway sound-effects.

I was pretty happy with my first print as it had quite good quality and no specific issues presented themselves during the print. Not that one should expect printing issues to be all gentlemanly and present themselves during a small print like this, they will much rather sneak up on you silently and stab you several times in that soft part of your kidney where you can hardly feel a thing but which can be quite detrimental to your health.

So, armed with the happy feeling finally having created something with my 3D printer, I ventured into the untraveled realm of printing random stuff. I started off with the cliché iPhone case (link):

I printed some hearts for my wife (I made some jewellery with these, I'll probably still do a writeup of this):

And then started with the Standard Raptor hand from e-NABLE, my first assembly. I plan on writing a lot more about the e-NABLE designs and my experience in printing them, but I wanted to keep true to my promise of posting many more awesome photos and videos, so here they are:

And a video of how it functions:

For now I have only posted the nice pictures of successful prints and have left out the failed ones. But it wouldn't be an honest account of what actually happened if I just ignore those prints or the lessons I learnt from them. So in conclusion (and an extended one at that) here are some very important lessons I learnt during the process of printing all of the above:

1. Make sure the hotend fan is always on: when I started tuning my stepper motors with Pronterface and started using the extruder for the first time, I didn't make sure of this. The result was a bad case of temperature creep. The fan doesn't cool the heat exchanger fins of the hotend, causing heat to creep up from the hotend nozzle (where it should have stayed) and through the whole hotend towards the extruder. Then the properties of the filament are not linear anymore so the extruder keeps extruding filament but all of it doesn't exit through the nozzle. I made the error of turning the printer off to investigate why my extruder motor was sounding like it was skipping steps constantly, which caused the filament to cool down and the whole hotend to clog up. This led to weeks of ignorant frustration, until I followed a fellow maker's advice to put the hotend on a hot plate, which solved my problem instantly. Since then, I make sure every time.
2. Don't over-tighten your brackets and fittings: I did this with the coupling brackets that hold the Z-motor shafts and the threaded Z-axis shafts together. During one of the initial prints, I started hearing a slowly compounding crack that I couldn't place at first. When I realised where it was, the crack was almost halfway through the part. I fixed it mid-print with some Pratley Quickset (white) glue, which worked wonders and has been holding the part together ever since. My first print after that was the broken part.
3. Check the power and/or screensaver settings on your PC or Mac: these settings can (and most likely will) influence your USB communication to the printer. You don't want the printer to lose communication in the middle of a 5 hour print just because the screensaver went on or because your laptop went into sleep mode. On a Mac, my printer always stops after a while if I navigate away from the screen running PrintRun (Pronterface) for too long. Usually it starts again when you navigate back. If it doesn't, the hack I use is to pause the print in Pronterface (while the printer is still stationary) and then to continue the print again after a second or so. This usually works to get the printer moving again.
4. Invest in the highest quality grub screws and Allen keys you can find: I stopped counting the amount of Allen keys and grub screws that I have stripped trying to tighten the belt sprockets to the stepper motor shafts. It is highly important that these are as tight as possible as they keep your X- and Y-axis accuracy in check. I had weeks of problems with failed prints due to mid-print Y-axis drift, which is very irritating.
5. Wait till Slic3r is finished exporting gcode: this process my take a very long time in some cases where big print files are created. Some people have suggested using other slicers like Cura, which apparently speeds up the process greatly. In the case of Slic3r, wait till the export is finished before loading the gcode into Pronterface, otherwise you will have a failed print. Pronterface indicates the dimensions of the print in X, Y and Z once the gcode is loaded - compare this with the stl file's dimensions to check if all is good.

That is all for now. I might still edit this list of lessons, as I wrote down a bunch of important stuff somewhere but I can't for the life of me find that "somewhere" anywhere. Thanks for reading.

S