After a run up of making throughout the week, the bridge competition began at the Makery last Sunday to test the designs of our participants.Â In all, there were 9 entries (some last minute).
In short, the rules:
Bridge:May contain only balsa wood and Titebond 2 wood glue.Must fit within a 50 x 20 x 10 cm rectangular volume.May not contain more than 6oz of glue by wet volume.Must have a smoothish road deck no less than 6cm in width.Â – suitable for a HotWheels-style car to easily roll overDeck ends must contact the upper surface of the test rig support planks.Deck must have no more than a 10% grade (where grade = 100 * (rise/run))Deck must accommodate the load plate.Some part of the load plate must fall across the midpoint of the span.There are no limits on construction tools or technique.Scoring:The load plate is 10 x 5 x 1 cm, and has a loading hook extending from the center of the bottom surface which requires 1 cm annular clearance through and below the bridge deck.Bridges will be loaded progressively (w/ minimum shock load), starting at 5kg and progressing in 1Kg increments to 10Kg.Upon reaching the maximum load, the bridge must hold for 1 minute.Â – Disputes as to whether a bridge ‘held’ will be resolved by voteBridges that fail will be ranked by the weight carried without failure and bridge mass.Bridges that do not fail will be ranked by the mass of the bridge.Testing:The open span between the support planks is 30cm.The open span is betweenÂ rectangular,Â fixed, smooth, level, coplanar planks with a thickness of ~2cm.The bridge may touch the top or inner surfaces of the supporting planks, but may not touch any other surface, nor be affixed to any surface.The load plate will support a wire or rod from which the test load will be suspended.
And so, our bridges took to the field.Â Most, thankfully, were able to take the designated test weight.Â Ironically, the ones that didn’t pass the test seemed to fail because of over-engineering.Â The resulting bridges flirted a bitÂ too close to weight limits and efficiency and ultimately couldn’t stand up to the test weight.Â The results:
As you can see, Dave K emerged victorious, with a design that was the lightest to survive the task of lifting 8kg, and which went on to lift 1452.61% of its own weight.Â Impressive!
By now you may have worked out that there is a category in the results called “Fail Weight.”Â Well, we at OMG like to test to the limits of design.Â Also, we’re all about 8 years old at heart and like to break things, filming the results in slow motion video if at all possible.Â So, without further ado…every last bridge getting destroyed/max tested to sexy music:
Join us for our next competition, to be held this Sunday!Â See the forum for details.