CREPinc.com

This message was sent to me by Mike, the other trebuchet man (who built the latest version, since I was unavailable :() :

After the failure of the counter-weight last week, the connection b/w the throwing arm and the ‘rock box’ has been re-enforced to withstand the stresses of 400 pounds of rocks. This required the dumping of the entire rock load. Then, new holes were drilled out and filed down to fit the new hardware. The 3/4″ threaded rod has been replaced by a 1″ dia. steel pipe, with walls 3/16″ thick. This extra 1/4″ of strength along with new 1/2″ bolts supplied by my Uncle Keith have been enough to keep things together. The trebuchet has been fired several times with this new configuration and it is working well. The hardest part of the entire re-build was attaching the empty 40-50# counter-weight box back onto the throwing arm. Then, hammering the 1″ pipe through the holes, so that the counter-weight will suspend from the throwing arm. Everything had to align perfectly, and even being 1/16″ off perfect alignment is a problem. But, with the help of my father, I was able to twist and
drive the pipe into the holes. After that, I re-loaded the counter-weight, one 8# bucket at a time.