Perfecting the Boomilever

By Alexander Kirsch

An essential goal of construction is to build something that is not only sturdy, but also as light as possible. Anything excess is a waste of material that only adds weight, while skimping on material will comprise its integrity. At the Wayne-Monroe Science Olympiad, many teams from across the state try to balance both weight and sturdiness in the boomilever event.

A boomilever is “a wood structure that is attached to a wall from a single point or area that holds weight”(https://scioly.org/wiki/index.php/Boomilever). To test the boomilever, it is mounted on a wall with a bucket hanging by a chain on the opposite end. Sand is then poured into the bucket until it is full or the structure snaps in half. Efficiency is then measured by dividing the weight held by the weight of the boomilever. That value is then used to score the boomilever’s efficiency; the higher value, the better.

At Thurston High School, Ji’on Newton and I have been building a boomilever since November. The philosophy for our design was “Start Simple.” Since neither of us had built a boomilever before, we wanted to make something basic to see where it fails in order to later make an improved version. The structure consisted of two compression members attached to each other  by some crossing beams and two tension members that attached the compression members to the hook.

This first design demonstrated mixed results at the competition. It was able to support the bucket, however it was already buckling in the compression members. This is likely due to the compression members not being flush with the wall enabling them to slide upward when pressure was applied to the hanging end. Sand was then poured into the bucket for maybe two seconds when the boomilever abruptly failed.

Its performance was perfectly summed up by Newton’s initial statement of “Well, should’ve built it better.”

The boomilever did not “properly fail” however. The maximum weight that a structure can hold is derived from when parts of the structure break. During the test, the structure did not break. Instead, a tension member came unglued from the base that attaches to the hook. After that happened, the whole thing split in half. Ending the test prematurely. This result was “disappointing” since a true maximum could not be determined due to no solid piece breaking.

Since the structure remained intact, our plan is to glue it back together properly and test it again.

Regardless of our plan of “back to the drawing board,” the Thurston team still received tenth place in the event out of twenty five teams.

The following week, the Thurston team did get the chance to snap their creation. After some generous gluing, the eighteen gram structure showed some surprising resilience. It held three thousand grams before the basswood cracked in two. It also proved to be very flexible, warping like a bendy straw which astounded those who were present. That exposed a critical weak point in the design.

The next design is going to have two pairs of compression members on top of each other as reinforcement to prevent bending. The team is confident that this next model will more than double its capacity, and secure a medal at the next meet.

Like us, we hope the boomilever will be just as resilient.