For printing parts for Dollo, I mostly use my trusty Prusa MK2 (now upgraded to MK2.5). It produces quality parts with good tolerances and does it reliably. My other printers are bowden setups and although they can produce quality prints, they are more prone to filament jams with certain PLA brands. I've noticed that even the Prusa suffers from this in extreme cases, but the direct drive extruder setup minimises the problems caused by filament not moving freely. With bowden, the pressure builds in the long tube and causes quality problems.

Since the Prusa is the only printer capable of printing all the parts for Dollo and other projects that require certain level of quality, it is quite busy and tied up most of the time. Getting another printer that can print with the same quality and reliability has been on my mind for a while. Since I upgraded the MK2 to MK2.5, I ended with some extra parts:
- bed
- extruder
- smooth rods for X,Y and Z
- bearings
- other bits and bobs

So I got the idea to put the parts in good use and build another Prusa. For frame, I'm going to use Dollo extension parts, I think it'll be robust enough. If not, I can always make it stronger with metal rods inside the extension parts.
As I have the MK2 heated bed (MK42), I'm planning on using Prusa fw so I have full MK2 calibration features. As I don't have the Minirambo board, I'm going to try to port the fw to RAMPS. If that doesn't work, then just buy the Minirambo. Also I'm planning to use DRV8825 or Trinamics stepper drivers, so that should improve on the already great printer.

I started the design work on the frame parts, I forked the Prusa repository. Thankfully the parts are designed with OpenSCAD, so modifications are easy to do: https://github.com/spegelius/Origina...tree/MK2_Dollo. Did a mockup of the original frame so I can re-create the part positioning accurately. Frame design is progressing quite nicely.
prusadollo.jpg