The mendel90 needs a bit of a spring clean, as its currently printing pretty badly. My plan is threefold:
Part 1:
A full teardown and rebuild of the motion system, replacing the belts that have worn, re-printing and replacing any parts that are damaged, and recalibrating and levelling the bed.
Remount the raspberry pi on the proper printed part, and run the wire to it that lets it turn the printer’s power supply on and off.
Reflash the firmware on the melzi to allow us to easily tweak the Z-height in EEPROM, so we don’t have to keep tweaking it in g-code when the machine dimensions change, and can just recalibrate and reset it periodically.
Update octoprint to the latest version.
Part 2:
A whole new extruder / hotend unit: Alex and I have gone halves on an E3D v6 extruder, which should be slightly better than the j-head we currently use, and allow printing of higher temperature materials like polycarbonate and nylon. This extruder can be built completely separately from the printer and swapped in when needed. It will require a PCB fabricating (which can either be chucked on an elecrow order if one is happening soon, or made in-house), and some ABS parts printing, so hopefully we can get it printing well enough for this after Part 1!
Part 3:
Replace the heated bed with an aluminium unit, with a printbite or similar surface. Add an inductive probe to the extruder to allow for bed probing, which means slight levelling errors and changes in printer dimensions in the future will be automatically calibrated out before every print 
I’ve already got the aluminium bed and some inductive sensors (for some reason).
If anyone has any other suggestions, reasons why the above plan wont work, or wants to help out, please give me a shout
