Staying on Track

With the frame of our prototype in place, we've spent the last few workdays tackling a much tougher challenge: fitting the track onto our frame. Turning square pieces of flat plywood into curved, angled pieces of track is no easy matter due to the complexity of the shape required. Each piece must be individually measured and cut to interlock with each of the other pieces and the frame, without any cracks or unevenness that could endanger riders. This process has its tradeoffs - the maximum width of the track exceeds the maximum width (eight feet) of standard plywood, usually at the sharpest point of the track's curve. To once again focus on safety, we opted to add extra plywood sheets only at the furthest reaches of the curve, where riders are less likely to encounter a joint between two sheets.

The curved nature of our track presents an additional challenge, since flat plywood tries hard to stay flat. Screwing pieces of track to the frame will hold a curve, but the track must be thin enough to be bent into shape, while at the same time remaining thick enough to remain stable under the forces that the finished track must carry. Since our initial testing found half-inch plywood to be too unstable, we tested our prototype with 3/4-inch plywood.

When that turned out to be too difficult to bend, we adjusted by cutting a series of grooves into the back of our sheets to approximate a more pliable 5/8-inch depth. For the sake of efficiency and price, this means that our final construction will be done with 5/8-inch plywood, as cutting grooves is extremely time-consuming and the structural benefit of the extra material is negligible. Finding the right depth of track has been been one of many lessons learned through the challenges of prototyping, but we're confident that the final Cyclodrome will be that much better for our experience.

With the power of imagination, it's more than just a prototype.