A bridge built out wood and based on the drawings that FIRST gave us does not give you the proper balance and properties. You need to add weight to the ends to make it performance like the one used on the game fields [which are metal].
They are separated into 4 stacks, each with a 25lb weight and a 10lb weight.
Our machinist made shaft adapters with an od the matches the inside of each weight and an id, that matches a 1/2" bolt.
4 bolts are somehow (I can’t remember) attached to the underside of the bridge.
We slide the adapters into the weights and the weights onto the bolts, then put a nut on the end and voila. This way the bridge is properly weighted, but we can easily remove the weights, so that we don’t have to carry a 200lb bridge everywhere.