I made a new aluminum extruder block to space my nozzles 75mm apart. Now I can use the entire space on my XL HBP
I can use the ditto function of the Sailfish firmware to print 8 rows of 37.5mm wide, or 4 rows of 75mm wide objects. You can print certain items wider than 75mm if you orient them right like this cute
A word of caution: You will have to change your home offset in the firmware, make your x toolhead offset 75, and possibly your start gcode to make sure the wider trolley doesn't hit the left side of the bot! You will also need to reverse the direction of the left extruder, because now you have two right handed extruders.
I bought a length of 5/8" square aluminum bar stock from the local metal supply. Cut it down to 114mm wide.
I used the original Replicator bar to layout the holes for the extruders, nozzles, and mounting screws:
I made the following holes in the same location. (based on the right side of the bar)
* The right side nozzle (6mm threaded)
* The 2 right mounting screw holes (3mm smooth)
* The top 2 screw holes (3mm threaded)
* The bottom mounting screw holes (3mm threaded)
I used a set of digital calipers to make a center mark 75mm left of the right nozzle hole. I used this mark to layout the left nozzle and 2 mounting holes.
The filament hot end tubes aren't long enough to put the top nut on, but it works fine with the bottom nut tightly against the bottom of the bar with the tube flush on top. Assemble the hot end and nozzles, and check for level between the two nozzles.
Print the XL Filament Guide and the Airflow Dam to use with the new spacing. You will need to setup the left extruder with a right handed plunger, or roller bearing setup. I have included updated parts from my thing http://www.thingiverse.com/thing:64919
Use this OpenSCAD file to make yours fit your parts.
There was too much air going down through the now open center, so I made the air dam. I pressed out the guide tube keepers from the original and put them into the new one.