For my unofficial Picasso Design Challenge I needed some more ABS filament for my 3D printer in order to complete the fourth motor unit. The filament turned up yesterday, all the way from America, and expensive! but I knew that when I bought the printer. After 3 hours I had managed to get my printer going again. I had used almost all my previous filament to make three motor units and it transpired that there was only about 5 cm of filament left, which was of course inside the feed tube. Withdrawing the filament didn't do any good as it just withdraw into the feed tube. Eventually I had to remove the feed tube and then remove the 5 cm of old filament. Unfortunately when inserting the new filament all I could get was a knocking sound coming from the print head and no filament being extruded. After some head scratching I decided that there was no option but to disassemble the print head to see what was going on.
I haven't taken a 3D print head to pieces before so I had no idea what to expect. Plus it is over 12 months since I purchased the printer and I had no idea where the manual or the tools were. Still, there is the internet so I managed to find a manual which was no use but it did lead to a YouTube video which was very useful, if a little fast in progressing through all the steps. I had to go and find the tool kit as it had the Allen keys needed. It did seem like I had to disassemble the entire thing but eventually I was able to get to the step motor driven filament feeder and found a 5 mm piece of filament nestling in the print head. This seemed to be preventing the new filament feeding in properly. I'm not sure why it didn't melt and let the new filament in, but it didn't. After some messing about I was able to re-assemble the print head and re-install it in my printer. I was more than surprised when it actually seemed to be working again, only to be disappointed after 30 minutes when the print became detached from the heated plate. I then had to do a print head calibration and reset the plate material to perf board as it had accidentally been changed to something else. Whatever I did, it seemed to solve the problem and I was able to print the final motor unit support.
Installing on the display was quite easy as I just had to remove the support leg and add the 3D printed motor support. Fortunately I was able to do this without having to remove the bottom two layers of acrylic from the display.
This left the connection of all eight step motors to the Arduino being used to test everything. I decided to reduce the number of step motor drive PCBs by driving the four forward/backward step motors from one stepper PCB and the four direction step motors from a second stepper PCB. The idea was to simplify the wiring and save space. I needed to create a distribution board which I did using Veroboard. All it contains are connectors so it wasn't that complicated, although everything was close together as I was trying to save space and that made all the soldering and connecting difficult. Eventually I was able to get everything connected and I now have four drive wheels moving in the same direction and four direction motors, also all moving in the same direction, see the video below.
Something that I had not really thought about was that all the wires needed to connect everything have to go somewhere. There are eight step motors with five wires each, plus the wires to the distribution board, which makes for a total of 50 wires, all of which I will somehow have to stuff underneath the display, along with the battery and Raspberry Pi/Arduino. At the moment everything uses push connectors and the Dupont interconnection wires are rather feeble which it comes to sticking in the step motor PCBs, so there is a tendency for everything to become unconnected. I will have to be very careful and fix all the PCBs and boards to the underneath of the display and then route all the wires nicely. I think that would all be possible but then I still have the Pi Camera V2 to fix to the underneath so that is going to complicate everything.
Dubbie
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