CONTINUOUS LIQUID INTERFACE PRODUCTION WITH FORCE MONITORING AND FEEDBACK

A method of making a three-dimensional object (31) is carried out by: (a) providing a carrier (15) and an optically transparent member (12) having a build surface, the carrier (15) and the build surface defining a build region therebetween, the optically transparent member (12) carrying a polymerizable liquid (21); (b) advancing the carrier (15) and the optically transparent member (12) away from one another to draw the polymerizable liquid (21) into the build region; then (c) optionally, partially retracting the carrier (15) and the optically transparent member (12) back towards one another; and then (d) irradiating the build region with light to form a growing three-dimensional object (31) from the polymerizable liquid (21); and then (e) cyclically repeating steps (b) to (d) while maintaining a continuous liquid interface (22) between the growing three-dimensional object (31) and the optically transparent member (12) until at least a portion of the three-dimensional object (31) is formed, while during at least some of the cyclically repeatings: (i) monitoring a transient increase in tension between the carrier (15) and the build surface through the growing three-dimensional object (31) during the advancing step (b), and optionally monitoring a transient increase in compression between the carrier (15) and the build surface through the growing three dimensional object during the partially retracting step (c); and then, when the transient increase in tension has substantially subsided, (ii) initiating the partially retracting step (c) when present, or initiating the irradiating step (d).