Many of our followers and customers have enjoyed our tops, but when we launched our Spinning Top Base, we were pleasantly surprised that it became an instant hit within the spinning top community. Customers quickly realized it provided longer spin times, and many experts were asking, “How did you do it?”
We recently sat down with the owner and founder of Bruce Charles Designs, Bill Strahan, to get all the details on the design and development process for his best-selling spinning surface. We think you’ll enjoy getting to hear from him on the entire process, from design criteria to the finished product!
Bill had a list of things he had in mind when creating the perfect spinning top base, including centering the top, provide long spin times, have a long-lasting surface, using glass material, and look appealing. Based on this list, Bill then needed to determine the specific type of glass and the dimensions for the spinning top base.
Type of Glass
Bill researched different types of glass for a spinning surface with an eye towards the mechanical properties. Most of the lenses on the market are designed for optical properties, but for spinning top purposes, this doesn’t matter at all. (As an aside, this is also why we don’t specify a focal length for the lens but specify the radius of the curved surface.) It became apparent that any glass would work, but we chose fused silica glass for its much greater hardness while still being affordable.
As to the radius of the concave surface, much thought went into this. If it is a more curved lens, then energy is wasted, but a lens that doesn’t center the top isn’t useful. Solving this to Bill’s satisfaction involved a tremendous amount of experimentation. He played with off-the-shelf concave mirrors (such as makeup mirrors) and quickly determined the curvature was too significant. He then tried some optical lenses and liked them more, but he wanted to get more experience with very shallow curved surfaces. Bill even took flat round mirrors and forced them into shallow curved pockets routed into plywood! Yes, he broke more than a few mirrors, but he also learned that a very slightly curved surface was all that was needed to capture a good spin. He was seeking long spin times, and the flatter the surface, the better. So, he experimented to find the least curved lens that seemed like a good compromise between centering the top and not wasting energy on the curved surface.
Bill eventually settled on a radius of 800mm, which results in the center of the lens on the 100mm diameter lens is only 1.44mm (about .06”) lower than the edges. The curvature is very shallow, so although it won’t capture an out-of-control spin, it will center a well-spun top and give very long spin times.
For the 150mm lens, there is a larger area to capture a spin, so Bill increased the radius for a flatter lens. Even though it is 50% wider than the 100mm lens, the center is only 1.7mm (about .07”) lower than the edges. The radius of curvature, at 1500mm, is almost twice the radius of curvature of the 100mm lens. It is much flatter. It is still enough to capture a slightly off-center spin, but it should provide slightly longer spin times than the 100mm lens due to the flatter surface.
At this point, Bill knew the material he wanted and the curvature radius to specify with a lens maker. Now he just needed to decide on the overall thickness for the lens. Time for the classic TLAR principle of “That Looks About Right.” Bill drew up a 3D design of a few different thicknesses and printed them on his 3D printer. Of course, they were useless for spinning a top on, but they did let him hold them and turn them over in his hands, and he was able to select the thickness that looked about right. Once this was decided, it was time to make the lens!
Bill says this was a fun process from start to finish, and he still has one of his early prototypes for a multiple surface spin base. He made this base from plywood with concave pockets routed out into which he pressed and glued 8” flat round mirrors. He had three adjustable feet on the bottom of the plywood base to level the surface, so the minimal curvature was enough to center the tops. The two mirrors provided a place for people to compete on spin times, and they were large enough to prevent too many accidents. We sometimes still use that surface when testing tops today!
Bill's vision to create the best spinning top base has come to full fruition. Two of the best-selling products on the spinning top market, our glass lenses create the best spin experience for any top spinner!