I recently built a Prusa i2 and I'm having issues getting it to print bridges correctly, or at all.
When it passes over the edge of the last perimeter and starts the bridge, the filament completely severs and a new piece of plastic dangles from the hotend before reaching the end of the bridge, where it anchors and over time forms a noticeable blob of plastic. I've attached a picture of a whistle I printed that has this issue, and also has several holes in the top infill due to barely any of the infill threads actually printing. It was printed at 0.25mm layer height with 0.5mm line width.
I also notice this happen to infill when I use layer heights < 0.3mm with high speed, instead of stretching properly, the filament breaks and starts forming several pillars where sections of the infill meet. By this I've completely ruled out rectilinear/line/etc patterns and only use hexagonal patterns in Slic3r since that is the only one that has a significant amount of support from lower layers.
I am using a 0.5mm J-head nozzle with 1.75mm Ultimachine natural PLA, however I have also printed with other PLA filaments and at temperatures ranging from 180 through 220 degrees. I've tried with and without a cooling fan, nothing seems to make any difference.
Any advice would be greatly appreciated.
