Wood Bearings for a Floating Arm Trebuchet

The woman on the phone said she needed some wood bearings for a 3/4" shaft, with an 1/8" wall. When asked what they were for, she responded evasively, "A machine".

We explained that what we build, and how we build it, would depend largely on what particular kind of machine, and the expectations for it, and when directly asked what "kind" of machine, the caller quietly said, "catapult".

Thus began our brief but rewarding association with Katherine Hikita, an engineering student at McGill University in Montreal.

Katherine was the captain of a team of students, competing in the Canadian Wood Council's First Annual Engineering Competition. The Council solicited entries from schools across Canada. The project was a catapult of one variety or another, built entirely of wood, with the exception of screws and other minor fasteners.

The McGill team elected to build a floating arm trebuchet, a 21st century version of the awesome, medieval castle-buster. Katherine needed bearings for the throwing arm's pivot point, and for the wheels that carried the arm's moving end across its rails.

This was the sort of project Woodex gets excited about. We set to work designing and building the bearings, with vague hopes we might be invited to Montreal and get a chance at some of that wonderful smoked meat from Schwart's Deli.

The competition, however, was held not in Montreal, but at Carleton University in Ottowa. Worse, while a cross-country flight to Ottowa wouldn't ordinarily be a bad thing, the affair was held on a bitter, sub-zero January day, when it was far too easy to think of other things we'd really rather be doing.

Thus, we were forced to be content with Katherine's report, together with a video she was kind enough to send along after the fact.

East Coast Catapults placed second in the competition. A doweled & pegged, all-hardwood ballista built by a pair of cabinetmakers in a trade school won first prize, even though it lacked the range of the trebuchet, and broke in the intense cold of Ottowa.

We understand Katherine's since gone on to collect graduate degrees, and we haven't heard from her since the aftermath of the competition. We hope, however, that one of these days, when we most need the variety, she'll show up again with an application to top the trebuchet.

Katherine, wherever you are, thanks for a fun application and a great story!