RepRap: Darwin almost finished!
More progress, more videos!
I had a lot of time on my hands this week, so I almost finished my RepRap! Here are some time lapse videos.
Gaining height: part 1 (40 minutes of work)
This video shows the first steps to adding a Z direction (up) on the
X-Y frame. On one of the axes is the motor that rotates a threaded rod
that is synchronized with three more threaded rods. A MDF base plate
lies on 4 nuts that rest on this threaded rod. This is the Z axis.
Gaining height: part 2 + 3 (15 + 45 minutes)
The moulded parts that I got from bits from bytes had a lot of holes that were note completely through. They had to be drilled through. I didn’t drill the holes exactly vertical. Looking back, this was the cause of a lot of problems and alignment issues later on. It really illustrates the power of additive fabrication ("fabbing"): you do not need to drill holes if they’re nicely designed in. When you start drilling your own holes, it becomes obvious how imprecise human hands are compared to fabbing.
Attaching the Base diagonals
These diagonals greatly strengthen the structure. The can also be used to attach parts to and guide wiring. I put some nuts on the base diagonals so I could glue them to the ATX (computer standard) PSU (power supply). This makes the entire RepRap 3D printer a compact machine of 0.5×0.5×0.7 (width x depth x height) meters.
I used simple M5 bolts instead of grub/set screws since I had a lot of them and it actually looks nice to have lots of bits in either black or metalic 😉
Building the extruder
Here I’m building the extruder. It seemed that the motor coupling (from the GM3 motor to the flexible drive) was to thick. The motor didn’t fit on top of it. That was mostly because the flex drive ended up a little higher because of how I soldered it to the screw that screws in the plastic fillament. I tried making it a bit shorter with a knife, but that would take too long I realized soon, so I added some rings between the motor and where it is normally attached to distance it a bit.
Attaching the screws to the extruder:
Current state of afairs
The only problem left is that I sometimes get communications errors and that the extruder doesn’t heat up (you can still touch it). The thermistor gives a value of 67′ Celsius (which seems about right). Holding the soldering iron against the extruder head heats it up and it indeed registers a higher temperature as it should. So it’s not the 10K thermistor / Analog2digital measurement problem (yet?)
The extruder didn’t just heat through (software) PWM, because it’s off for a long while and then pulses for a short while, repeats, and so on, and so on. This long period’s without heating seemed to me a bug that might have been fixed. My next step was to compile the firmware from SVN since this could very well be newer.