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

The RepRap Ecksbot 3D printer - final hardware checks and setting up firmware and software

With my 3D printer assembled and most of the electronics sorted (see my previous post), it was only a matter of moments before I could reach my long awaited goal of actually implementing the device. Or so I thought. Turns out I actually had loads of checks to do, installs to complete, settings to figure out and set and many important lessons to learn. I'll try and cover most of the important aspects below and I'll no doubt forget some important pointers in doing so, but please feel free to post a comment if you have any questions.

Step 1: Pre-anything mechanical checks

1. Make sure that everything you put together in the mechanical assembly is securely fastened and levelled in the correct place.
2. Check that your heated printbed is mounted securely and levelled on the aluminium Y-carriage, using the 4 bolts, 4 nuts and 4 springs.
3. Check that the belt sprockets are very securely fastened to the X- and Y-motors (this is something I cannot stress enough - if the grub screws loosen mid-print it will seriously damage your print) and that the belts are tight enough but not too tight. Test the tightness with your finger, it shouldn't deflect more than about 5mm when pressing down on it with light force. (This value was heuristically chosen but should give you an adequate idea).
4. Test the quality of movement of all axes by moving the carriages from end to end. Adjust axis alignment, oil bearings, fasten nuts and do anything else to get a smooth, unhindered movement in all axes. To get movement in the Z-direction, just turn both threaded shafts connected to the Z-motors in the same direction.
5. Do bed-levelling by positioning the hotend nozzle a few millimeters above the printbed and adjusting all relevant axes in order the move the nozzle over the entire area of the printbed. Adjust the bed-level by fastening or loosening the bolts at its four corners.
6. Make sure the extruder hole aligns perfectly where it meets up with the hole in the top of the hotend so that filament can fit nicely through from top to bottom. Test this by pushing a piece of filament in from the top (pushing down on the extruder spring clamp to allow the filament to go through) and letting it go almost to the bottom of the hotend where the nozzle starts getting narrow.

Step 2: Pre-anything electronic checks

1. Check that your wiring is clean, neat and out of the way of any moving parts. I've done this with my wiring on the printer itself (small cable ties are awesome for this job), but the wires lying next to my printer (those connected to the controller board) are a totally different case. I'm still planning on printing an enclosure for the excess wires and the controller board.
2. Make sure that the stepper motor wire connectors are securely connected to the motor ports.
3. Make sure that the two Z-motors are wired in parallel. The separate groups of wire coming from both motor connectors should be joined so that a single group goes to the controller side where a single stepper motor driver controls both motors. This should be more evident once I supply a wiring diagram (or if I do?).
4. Be sure that every important electrical component on the printer is connected to the relevant ports on the Gen 7 control board: the 5 stepper motors to the 4 stepper motor driver connectors, the heated printbed and its thermistor to their ports, the hotend and its thermistor to their ports, the three limit switches to their ports, and the 12V and GND connections from the power supply to the power input ports. The 12V hotend fan can also be wired directly to these power input ports as it should always be on during all prints in order to help dissipate heat from the hotend.
5. Turn the pots on your stepper motor drivers all the way down. On my Gen 7 board I have four Polulu A4988 drivers and on them "all the way down" means all the way counter clockwise.
6. Do not connect your USB cable yet, and also don't switch on the power supply yet.

Step 3: Software

The basic set of software installs you'll need in order to have everything up and running is as follows:

• The MCP2200 USB to Serial driver to let your PC communicate with the Gen 7 controller board (on Mac OS X Yosemite this is capability is pre-existing and no drivers are needed; I am unsure if this is true for other Mac software versions, though).
• Slic3r, which converts STL files into gcode which the printer can interpret.
• Printrun/Pronterface (on Mac it is called Printrun-Mac) to enable communication between your PC/Mac and the printer.

Downloads for these software packages are provided at this OpenHardware link.


Step 4: Hooking up your printer and making stuff move

Once the necessary software is installed, it is time for the long awaited initial unveiling. At this point it's probably a very good idea not to let your excitement get the better of your logical thinking, as this might lead to some random failures and disappointment.

1. Connect the Gen 7 printer controller board to USB port on your PC/Mac. A red LED on the Gen 7 board should start flashing.
2. Open Printrun/Pronterface, making sure that the correct COM port is selected for the printer and that the baud rate is set at 115200.
3. Turn on the printer's power supply. Remember, your stepper motor motor drivers are turned all the way down, so nothing should make loud noises or anything (if they do, it's probably a good idea to leave everything and run). I suggest double checking the stepper motors one by one before switching everything on at once - just plug in the stepper motor you are testing, apply power and see what happens.
4. Connect to the printer from Pronterface. If everything functions as it should, you will hear a fairly load clicking sound coming from the stepper motors.
5. Tune your stepper motor drivers, using Pronterface, to allow the motors to receive the appropriate amount of current for printing purposes. Use this post as a guideline for tuning the drivers.
6. A very important step: calibrate your extruder! These posts give ample information about how to go about this. RichRap's blog is a vast treasure of valuable 3D printing information, I recommend reading everything he has ever written:
• OpenHardware extruder calibration
• RichRap's Slic3r is Nicer Part 1 (read parts 2 and 3 as well!)
• The RepRap wiki on calibration
7. Remember to check that your hotend fan starts blowing immediately when the printer is switched on. This way, when the hotend temperature is set from Pronterface, your hotend heat exchanger will stay cooled and the temperature won't creep up your filament and cause problems during extrusion (this happened to me and I had to learn the hard way).

So that's about it in terms of pre-print checks (well, that and all the millions of other things I forgot to mention). At this stage we are ready for the first print, which is what my next blog post will cover. I'm sorry that I didn't post any pretty pictures or videos and that it's all just a bunch of words. I promise to correct that with my next post. For now, here is a potato.

Source: http://www.moffatcan.org/shop/?product=potatoes-2

Peace.

S