Bridging is a term for printing layers over thin air without the use of supports. It may sound like an impossible feat, but with our MK2 and MK3 printers, it’s not that difficult. Keep in mind that the best results are achieved only over short distances because the printer’s fans need to cool the extruded plastic mid-air in order to create a solid connection. There are three key settings for printing good looking bridged layers: Slic3r settings, speed, and cooling.
The typical problem of bridging layers is sagging or drooping as seen in the photo above.
How to fix poor bridging:
Detect Bridging Parameters in Slic3r: Double-click the object you want to print, go to Object Settings and click the Plus button to open the menu. Select Layers and Perimeters – Detect Bridging Parameters. This will help Slic3r to identify the areas that should be treated as bridges.
Tweak the fan speeds in Slic3r: In Slic3r PE, double-click the object to open the Properties window. Then click the Plus button, choose Speed – Bridges and tweak the speed for printing bridges.
Obviously, the best solution is to change the orientation of the object (rotate it) until you get rid of the bridges completely and you don’t have to worry about bridges or supports. It won’t be possible in many cases, but the rule of thumb here is to try to avoid bridges and supports completely.