Summary

BCN3D++ Single Bowden extruder

Better, Faster, Bigger

This mod is based on the great work by altrome (http://www.thingiverse.com/thing:406531)
Aiming to get a better printing quality, faster printing, and bigger printer area I have redesigned a bit the original BCN3D+ head as follows, to turn it into BCN3D++ wich can now print X=275,Y=195,Z=240.
Check the Dual Bowden version (http://www.thingiverse.com/thing:419287)

Instructions

Wider and higher printing area:

I've reduced the width of the head to the minimum possible, from 76mm to 48, that means almost 3 more centimeters of printing area thus going from 240mm to almost 275mm.
As a first test (that btw works wonderfully) I've printed a new smaller extruder support in ABS, instead of making a new metal one, as I don't have access to a mill until september. As the top part of the extruder will never reach high temperatures nor the melting temps, I decided to try to print it in ABS.
To get the smaller size head I moved the layer ventilator support from the rear to the front this allows to join the head's support to the maximum.
I also glued the two small extruder vent to each support, with loctite, works great.
As we use a bowden and have removed the extruder motor from the head, printing height can now go from the original 200mm up to 240mm.
To take advantage of the new printing size, the firmware needs to be modified, and a larger glass will also be needed in order to take advantage of the new bigger width.
To be able to use a larger glass, the bed's holding bolts need to be "hidden" under the glass.
To change the firmware, in file "configuration.h", line 320, change bed limits to:
// Travel limits after homing
define X_MAX_POS 275
define X_MIN_POS 0
define Y_MAX_POS 195
define Y_MIN_POS 0
define Z_MAX_POS 240
define Z_MIN_POS 0
x from 242.5 to 275
y from 210 to 195 (as I now use clamps instead of bolts, this could be kept as 210 but then I would have to be very carefull where to place the clamps on every print)
z from 200 to 240

Better printing quality and higher speed:

It is well known that the heavier a moving object is, the bigger it's inertia will be, thus needing more energy (motor strength) to change directions, so by using a Bowden system the motor is removed from the head, thus reducing its weight significantly from 765gr to 211gr!
Removing more than 550gr, will allow higher printing speeds, and having much less inetria forces, a better quality will be obtained.
BOM:
Used the original Parts from altrome mod (http://www.thingiverse.com/thing:406531)
and:
modified base in ABS (originally in aluminium) BASE_UN_EXTRUSOR.STL, print in ABS with 0.2 layer and 80% fill
Enlarged fan support VENT_BASE_UN_EXTR.STL, it's the original BCN3D+ part, just a bit longer to bolt it on top instead of the bottom of the base.Print in PLA with 0.2 layer 40% fill
I also changed the Slic3r setup to set the retract to 8.