I learned that the main goal with Bowden extruders is to reduce the number of retractions in a print. Even fast and long retractions often leave blobs, so we have to fight those.
Slic3r 0.9.9 contains a number of features for that purpose. Here are the recommended settings:
- avoid crossing perimeters (Print Settings): on
- only retract when crossing perimeters (Print Settings): on
- retract on layer change (Printer Settings): off
The first setting will also cause Slic3r to finish each island completely before moving to the next one, reducing the need for retraction.
Slic3r 0.9.10 introduced a new useful setting to avoid blobs upon retraction:
- wipe (Printer Settings): on
These settings should help you getting good prints with your Rostock, RepRapPro, Ultimaker or whatever.