This is a working dual extruder hotend and effector platform modification for the Rostock Max V2. The goal was to mount two E3D V6 hotends in the stock above-the-platform position by creating a new effector platform with a wider center hole.
While it is possible to assemble this tool plaform as intended, getting the wires is a very tight fit and the force from the wires tends to twist the heater blocks, loosening the heat break and creating potential failures.
The platform assembles just as well as an under-mount, and the images here are of the dual extruder in use there.
This is a work in progress, and revisions will need to address either the fit of the hot ends or else make changes to better take advantage of the extra space from being mounted under the effector platform.
Note that both metric and imperial hardware are used, since the Rostock is primarily built to imperial units, but the arm joints are metric.
The rod for the arm connections is M3; either an M3 smooth rod for the stock arms or a threaded M3 rod for the TrickLaser carbon fiber arms. The screws securing the rod to the effector platform are 4-40. The upright screws connecting the effector platform are 6-32.
Rendered objects and images are posted on Thingiverse at: http://www.thingiverse.com/thing:1083270
The stl used for the pictured preview of the E3D V6 hotend is from: http://www.thingiverse.com/thing:341689