Protocols for minimizing the leading edge bulge in stereolithography

The leading edge bulge is a known defect in stereolithography with free-surface recoating. It is a resin excess that remains after deposition over a deep-to-shallow topographic transition, the leading edge of the cavity. In this paper, we explore an approach based on changing the gap between the recoating blade and the previously cured layer to minimize the local resin surface unevenness by suppressing resin excess. By means of numerical simulations, different blade trajectory configurations have been considered. The results show that the amplitude of the leading edge bulge can be reduced to a minimal value by a blade actuation protocol of lowering then raising the blade as it moves over the leading edge, without increasing the recoating process time.