I have had a great deal of difficulty with dual material prints (e.g. ABS + separate HIPS support). The extruder change has the head paused over the print for a considerable period at the start up of the new material. This leaves a melted surround which typically eventually bulges in the Z axis. this eventuall creates a "catch" point where the fill (for example) is ripped apart.
I have tried a number of strategies to try and alleviate this:
- - Randomisation of the layer start point (instead of default fastest)
- Alignment of layer start point with a point outside the model - and the addition of a "sacrifical" structure. The idea being to have the print layer start with this structure for the extruder change so that the main model prints with the extruder fully charged and mobile. Unfortunately I cannot get the sacrificial item to be forced to be the first item printed in the layer...
Is there some setting I am missing? Or is there some reliable way to use a separate sacrificial / wipe structure to prevent the extruder changeover pause being right in the middle of the model? The Makerbot slicer creates sacrificial structures for each extruder which both wipe the non-active extruder and ensure clean model transitions with the new active extruder.