After upgrading my Prusa i3 MK2 to MK2.5, I was left with some parts I wanted to put into good use. Since I really like how the MK2 had performed, I thought to rebuild it but with my own design in it. Having built couple of Dollo3D printers, I chose to use Dollo building blocks.
I've had the printer working for over a year now and it's still doing well. I'd say the quality is on par with an original MK2. The calibarion sequence was a full pass on first try, which is kinda expected as all the axes are correctly positioned by the parts compared to the threaded rods on original design. Since I use RAMPS with this, I'm running a modded Prusa FW: https://github.com/spegelius/Prusa-Firmware/tree/MK2_323_RAMPS_R4E
I haven't noticed any quality issues caused by the printed frame, even with larger parts. I did have an issue with the first version of the bed carriage and the Y-belt holder after printing some ABS, the heat got it loose, but I did an update and so far it has been working fine, although I haven't printed much ABS since then.
I used the Prusa sources and modified and created new models as needed. The source can be found here: https://github.com/spegelius/Original-Prusa-i3/tree/MK2_Dollo Also the parts can be found there, not uploading all of them here, at least not yet. See frame.mockup.scad, it has mostly up to date list of parts.
Additions and changes: - added RAMPS version of the electronics covers, with 40mm fan - X-motor mount with belt tensioning - X-ends: support two versions of the z-nut - Y-idler Dollo version: tension adjustment added - PSU cover for 360W PSU - lot of parts have Dollo variant added - other minor changes and fixes
Pros: - lighter bed since the bed carriage is printed - somewhat modular, extending the frame is simply printing more parts - the frame allows attaching stuff with bow ties
Cons: - obviously the frame isn't the most rigid one - bed carriage might bend when printing large parts that warp - bed temps @100C or more? Not very well tested
BOM & instructions: - TBD if someone is interestted in building this, let me know and I'll try to get these done.
My current MK2 Dollo setup: - RAMPS 1.4 - 0.9 motors X and Y - R3 extruder (needs small fw change) - 230mm Z (needs longer smooth rods to fully utilize the threaded rods)