This mod is based on the great work by altrome (http://www.thingiverse.com/thing:406531) and my own Single Extruder Bowden (http://www.thingiverse.com/thing:419278). Aiming to get a better printing quality, faster printing, and bigger printer area I have redesigned a bit the original dual BCN3D+ head as follows, to turn it into BCN3D++ wich can now print X=245,Y=195,Z=240. check the single Bowden version (http://www.thingiverse.com/thing:419278)Same idea has been applied to the dual extruder head, both motors have been removed, and placed on the external support. Dual head width has been also reduced from 98mm to 76mm in width and space between the extruders is now 28mm instead of 43mm. Best of all the head's weight, has been reduced from around 1.300gr to 300gr!! that's 1kgr less weight to move! Height has also gone up to 240mm. so new values for the fw are: // Travel limits after homing define X_MAX_POS 245 define Y_MAX_POS 195 define Z_MAX_POS 240 x from 230 to 245 y from 190 to 195 z from 200 to 240 To get both extruders closer I redesigned the bowden coupling to home both extruders in a single part. Note that as the right extruder must be tunned separetly, bolts are made accessible for it. Once again I printed the Dual base in ABS (waiting for the aluminium in september) The design is made in such a way that switching from single to dual extrusor can be done in a matter of minutes, using a couple of bolts, without having to remove the whole head, only the extruder base. (firmware has also to be changed of course.)