We discovered that the second head often touched the object when printing and even if you retract the material of the inactive nozzle, there is often a small amount of material on the nozzle tip that can leave traces.
As an example, see the left part in the picture below. This part was printed with a standard Dual Extruder design, the right part is printed with our rotating Dual Extruder.
The green material is ABS, the white material is HIPS (soluble in Limonene) meant as support material.
To prevent this, a radical design change was required, we came up with a completely new dual head with rotating support and inclinated nozzles, which will avoid the unused nozzle hitting the object during printing.
The mechanism explained. When head #1 is printing material (red in the picture below), the second head is rotated away from the print area and can't damage or mark the object and vice versa, when head #2 is printing support material (green) head#1 will be rotated away. This furthermore allowed to reduce the distance between the nozzles, improving the overall object print size area compared to a standard dual head.
Interactive 3D view
Click the arrow button to initiate a interactive 3D view of the DualHead, use the mouse with click and drag to change orientation and the mouse wheel to zoom. Interaction is already possible during the loading process. Works also on mobile/tablet! Use one finger to drag and change orientation and pinch to zoom.
Video of the dual extruder
The software used is KISSlicer Pro, one of the clever things in KISSliser is that the support material is only on the "interface" area. This saves a lot of dissolving time and thus uses less (more expensive) support material and the material limonel that is required to dissolve it.