The 3D Printed Bridge Project Continues!
Assorted 3D printed bridge experiments using PLA-FDM and HP-MJF printing methods
And the WINNER IS:
John’s research into 3D printed bridges is ramping up with some exciting results! In a nutshell: The HP-MJF (nylon 12) method shows promise, but requires extremely detailed models with resonance chambers to get the stiffness to mass ratios in the ballpark of a wooden bridge. With this method, it’s tricky to design with holes to drain the un-sintered nylon, or to make the resonance chambers small enough to allow optimum acoustical properties. Surprisingly, the cheapest and most prevalent printing method for consumer-grade printers (“FDM” or “Fused Deposition Modeling”), has resulted in some of the best sounding bridges to date! Because the biodegradable plant-based PLA filament we’re using is slightly more flexible than wood, it is necessary to beef up some dimensions of the bridge architecture and slim down or remove others to mimic the tone of a wooden bridge. The result (after about 15 bridge iterations to find the best sounding dimensions) is shown in the above photo. Once establishing workable dimensions, it’s possible to print varying densities of infill to precisely match the stiffness and weight of a wooden bridge. I (John) have been teaching at Cornell using an alternative PLA bridge for a couple of weeks, and have been very pleased with the results! In general, the sound and performance have potential to offer a larger dynamic range and quicker response than my wooden bridges. I’m still fine-tuning the tonal properties, and will post a video sound comparison with a wooden bridge in the near future. Also, check out the new Saddle Rider ball bearing and piano wire wolf resonator in the above photo — more on that later! To receive blog updates, or to participate in beta testing, please SUBSCRIBE using the link below:
