Summary

This is based off the CoreCube SAKURA Rev.2 by ichibey. http://www.thingiverse.com/thing:161000
I have made a mechanical conversion to use Core XY and with the help of Dan Newman and Jetty behind Sailfish firmware have been testing variants of Sailfish for Core XY motion using the Mightyboard rev E and with a atmega 2560 in place of the 1280. Special thanks to those guys for making the firmware as that is what really makes this special.

Instructions

Update, I removed all previous firmware versions and now the Sailfish team is hosting them on the Beta site. Check here http://jettyfirmware.yolasite.com/ for URL and instructions. Again, I have removed all versions and they should no longer be used from here. They had the ability to turn on both bed heat and extruder heat at the same time and require special power supply considerations. The Beta site files are simply Core XY implemented in the normal version of Sailfish.

Notes about this. The Endstops are for HOMING only. They only work one at a time. In other words, you need to edit the start.gcode and home say X first, then back off a known distance so the X limit is no longer triggered but now you are in a known X location, then home Y axis. Finally recall an adjusted homing offset from firmware M132 XYZAB. The current start.gcode is not using this yet and as soon as I get a break today I will upload a new version of start.gcode to match this firmware. So that said, another warning is that the current start.gcode without homing will not cause the bot to lower Z axis when paused. Pause expects you to have homed X and Y and recalled offsets in order for it to work. So pause should work and will be part of my testing for the new start.gcode.

A huge Thanks to Dan Newman and jetty again for support. So that said, the fimrware I uploaded here is PURELY testing. DO NOT COMPLAIN to those guys or go posting in the Jetty forum about some problem you have. ENDSTOPS DO NOT WORK in the files posted. I have a testing version not yet ready for release. I'm hoping to drop it later on so check for frequent firmware updates as this progresses. Again, do Dan and Jetty a solid and run questions through here and not through the groups or forums.

Core XY in accel planner: mighty_one-2560-core_yx_v7.6.0.hex

OK, so basic BOM:
You need a MK7 or QU-BD MBE V9 extruder preferably with a genuine MakerBot stepper motor since they are shorter and lighter.
Mightyboard Rev E (currently requires swapping the main proc with a 2560)
Possibly some stepper drivers either A 4988s or DRV8825s without header pins soldered so you can flip them. This is because the Ultimachine motors used require 1.5A which is outside the range the stock stepper drivers can be adjusted to.
Again, the basic parts are the 280mm threaded Z rod motor from MakerBot used on Replicator, the mainboard, 2 Ultimachine NEMA17s, and a MK7 extruder complete.

For the idlers, I used a stacked set of 5mm flanged ball bearings with a washer in between. You also need 2 each pretty long lengths of GT2 belt. 2 of these Part Number: A 6R51MB09060 from SDP-SI
I got the two 500mm long 10mm rods from http://www.mcmaster.com/#
6112K47 $14.63each
4 each 10mm linear bearings from Amazon for Z axis
Then 2 each long LM8 linear bearings from VXB and then 4 more short ones for the Y axis travel.

You need 12 each 300mm long 80/20 extrusions, I got mine from Adafruit and cut them in half from the 610mm length.

Core XY cube