After banging on about it for months, I finally get around to trying ABS filament on my DIY Prusa. I heard lots of bad things about trying to print ABS, especially without an enclosure, so I was ready for the worst. Expectations were set low 😉
In this video I go through, in quite a lot of detail (!), my initial slicer settings, run some test prints and think about the results….
In this video I show how I ended up mounting all the electronics for the Prusa i3 MK2 clone. As the frame wasn’t as solid as the original’s aluminium one I decided that it needed a brace, which provided the perfect location to mount the Arduino, RAMPS, Raspberry Pi and all supporting parts.
I also added a brace to the other side – which gives me room for electrical expansion!!!!
I mounted the whole thing to an office desk, I picked up for free, and even though all four corners of the Y axis are square and sit on the desk, there is a slight amount of hammering when printing.
To silence that I drew up and printed out some little securing clamps which just make sure they cannot move. You can click the image below to download the STL for these clamps. They should work on any printer using the same Y Axis design and the Prusa i3 MK2.
Prusa i3 MK2 Y Axis Securing Clamps
And just in case anyone might find it useful, here is the STL for my RepRap Discount Full Graphic Smart Controller mounting plate, which is just a plate with mount holes in the right places and a boss on the rear tapered to accept the nozzle of a flexible cooling hose!!!
RepRapDiscount Full Graphic Smart Controller Mount
Really the only part of my Prusa i3 MK2 clone build that didn’t function as it should out of the box was the LCD Module with builtin SD card reader, rotary encoder, buzzer and stop button.
In this video I discuss how I tracked down the issues and fixed them. I also changed the ribbon cables for shielded cables as I needed them for how I was mounting the module – but it also assisted with preventing corruption.
The model I have is pictured below and its full title is a Bigtreetech RepRapDiscount Full Graphic Smart Controller.
Bigtreetech LCD Module, RepRapDiscount Full Graphic Smart Controller
During my trawling of the internet trying to find specific data for this LCD, (which I didn’t..) I used information from the documents below to build my own schematics, which are at the bottom of this post.
For anyone wishing to tear apart an HDMI cable to use as a shielded cable to the LCD Module, here is a pin diagram for a standard HDMI cable. (Although that isn’t much use as we are only using it as a general shielded multi-core cable! A decent HDMI cable has 7 single cores, and 4 twisted pairs inside their own separate shielding. This gives us 15 conductors, ignoring the shielding. The one I chose also had a metal braided wrap around the whole thing – I earthed them all to building earth)
As part of the fix I had to introduce delays into the instruction transmission from Marlin/Arduino to the LCD. Although I couldn’t find any official documentation of it, here is a post from Guthub which includes discussion from the coder who came up with the LCD handling in Marlin.
I discuss in the video how to arrive at these delays (noops), but below is how I finally set them to avoid corruption of the LCD. I have inserted these 3 lines into my Configuration.h file.
#define ST7920_DELAY_1 DELAY_1_NOP
#define ST7920_DELAY_2 DELAY_2_NOP
#define ST7920_DELAY_3 DELAY_1_NOP
Finally the schematics I drew up after confirming all the routing of wires from Arduino, through RAMPS, through connectors and into the various parts on the Bigtreetech LCD module.
Bigtreetech 128×64 LCD for RAMPS Schematic
RAMPS Aux3 Aux4 LCD Adapter Schematic with Arduino Pins
Continuing with my mission this week to actually finish the electrics on my DIY Prusa i3 MK2 3D Printer, in this video I make some modifications to the RAMPS board and the Arduino.
On the RAMPS I need to remove the 4 pin power connector. Now that the RAMPS board is not carrying the current to the heated bed it isn’t really a safety issue (although it might be if yours is carrying heated bed power…) but it just simply takes up too much space for how I want to mount it. And a soldered connection is more reliable that a connector, well usually!
I am also junking the polyfuses. Again not so much a safety issue now as there is only a little current going through them, but even so the 5 Amp one still feeds everything apart from the heated bed so they have to go. Replacing them with a simple blade fuse holder and fuses – you know,  like off of cars n stuff 🙂
In the last video I created a separate MOSFET board to handle power to the heated bed. The gate of the MOSFET is driven high by pin D8 of the Arduino, so I also add a signal wire from D8 that can then attach to my off-board MOSFET.
Lastly, I remove the DC jack on the Arduino. It isn’t being used or causing any issues, but I just don’t like it… well no, it got in the way of my board mounts.
That just leaves fixing the corrupted garbage that appears on the LCD after a couple of minutes. After quite a lot of time spent (more than quite a lot..), I have fixed it. That will be the subject of my next video.
I have changed my mind a few times about how I plan to finish off my Prusa i3 MK2 clone 3D printer… but now I have settled on a plan! None of it was particularly complicated, but I just want to arrange things in such a way that they are safe, tidy and give me the best result.
As I plan to add a physical brace to the Z Axis frame, IÂ want to combine that with a suitable housing for all the electronics. With the actual brace made I can start finishing off the electronics!!!
There are few items I want to do:-
The last of these is the item I am doing first – and it the subject of this video.
The links I discuss in the video are:
Below is my rough schematic showing how I will wire the RAMPS, Arduino and also a small external board that will perform the heated bed power switching. Beneath that the calculations I made to conclude that the AUIRFB8409 Mosfet would work fine:
Rough Schematic of an external board to switch power to the 24V heated bed, showing relevant parts of the RAMPS and Arduino
Main considerations in choosing the AUIRFB8049 Mosfet, with calculations
© 2023 Jules Gilson