Mendel 4


In the last weeks I finished the construction of my mendel.
With the help of Domonoky, we managed to mount the Nicrome-wire and the thermistors on the hot-ends.
We also mounted the printbed, the last electronics and connected everything.

The wiring was the first little problem: The cables from the makerbot electronics were far to short.
Domonoky had some plugs which were connected with 10 pins of a cable from the harddisc of an old computer.
Fortunately I found a cable which was long enough to connect the x-,y- and x-axis controllers with the reprap motherboard.

The second little problem was the wiring of the second extruder controller.
A short look in the manual suggested to connect the second controller on the same pins as the first one - fail!
Of course both extruders worked, but never alone!
The solution was a change in the firmware of the reprap motherboard.
We switched of the DEBUG led, set it to be the pins for the second controller and connected its direction and speed pin to the pin 0 and 1 on the reprap motherboard.

We had to change the z-flag, which also was far to short.

The axis controllers were to close to the printbed, so we removed it completely from the mendel and put it on the LEGO-Base. Not the best solution, but effective

After doing all this the first mm of filament could be hold right in my hand :-)

The first try extruding PLA was not that satisfying because the noozle blocked and the filament was compressed

Because the settings for ABS on a mendel were ready to download somewhere, we let the PLA extruder blocked, pulled the PLA out of it and switched to the ABS extruder.
Changing temperature settings, fasten screws and adjusting motor power we were able to "print" the first homogeneous ABS-Sculpture

Then we found out, that somehow the experiments with PLA on the other extruder loosened its gear - no wonder it was not working!

So we fixed the gear, cut off a bit of the printbed for wiping and built some soap stone isolators for the hot-ends.

The current problem is, that the motor power is set very high and the screws of the WADEs extruder are tightened. It's the only way to guarantee a homogeneous flow of filament.
This causes that the whole printhead gets quite hot after some test prints. Due to this, the filament gets soft and blockes the noozle like the PLA.
Lowering the motor power causes spinning of the motor.
Loosening the screws causes spinning of the filament.
Both ways lead to an inhomogeneous flow of the filament and incomplete layers.

Did I mention that the holes are no cirlces but ovals?


Now it's working, but there is still a lot of work to do :-)

Special thanks to Konrad from swizerland for the help with the Nicrome wiring and Domonoky for IT, electronic and reprap know-how. Also special thanks to László from hungary for the delivery of the special parts needed for the next dual-hot-end-prototype. The package arrived today.

Greetings from the lake of constance



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