A new board for the 3Drag 3D printer – there’s more than Sanguinololu
Let’s improve the 3Drag with this new board that allows to control a fan and (thanks to the ATmega2560 processor) add some code and accessory devices such as a display or an SD Card
When we first released our 3D printer, we tried to use some parts that were already available and tested, in full respect of the open source philosophy. In particular, we decided to use the electronic card Sanguinololu. The “open” firmware we chose, the Marlin firmware by Erik van der Zalm, solved the biggest part of the computer interface issues. The Sanguinololu was great, but being innovators by vocation, we looked around testing new developments. The first improvement was about introducing a fan, capable of blowing cool air on the just deposed layers, while the second came from the Sanguinololu weaknesses in managing the heated plate.
a few comments:
why a transistor buffer for the LEDs? a modern LED is plenty bright at a few milliamps, the IO can easily drive that and the step inputs at the same time
The limit inputs should really have a series resistor, something like 1K would limit the current, in the event of a short to 12V, to something reasonably safe
Replace the BUK6215s with something like VND14NV04 and the outputs would be safe from shorts and overtemp