I am having a strange problem with the extruder drive. When I print at 80mm per second or higher on a large part, the filament strips out on the hobbed bolt. This always happens after the first slow layer when the speed comes up to normal on long infill runs. If I change the build speed to 60mm per second, it will print all day.
Has anyone experienced this? Could the acceleration or jerk be set to high on the extruder?