My employer approached me with the task of creating a hollow wooden surfboard that could be produced on the company’s 5-axis CNC machine. The project was open-ended. The physical constraints of the project were defined primarily by the limitations of the CNC machine itself. I was responsible for all aspects of the design and prototyping process and consulted my supervisor only on technical questions regarding the CNC machine and Mastercam software.
I started by designing a small, basic surfboard using a surfboard design program called Shape3d. I then imported the file into Mastercam where I proceeded to further manipulate the 3D model. I sliced the shape lengthwise and added geometry to define the separate chambers. One of the more difficult tasks was designing a fixture that would hold the pieces firmly in place during the machining process.
I made parts out of a number of materials. Poplar and redwood were wonderful to work with. They machined very well and the threat of blowout was minimal. Ultimately, the intended material was an inexpensive wood called albizia. While it’s a very light material and can have a density similar to balsa, it is difficult to work with. The wood is pulpy and the sawdust is irritating to the eyes and sinuses. It has the potential to blowout in large chunks, which could potentially ruin entire parts. Also the density of the wood is highly variable, so if you are not careful in your material selection you could end up with a surfboard that weighs twice as much as the last one you machined.
After creating multiple samples and refining parameters such as wall thickness, fixture design, toolpath and dimensional tolerance, I proceeded to apply the process to a surfboard design provided by a master shaper. The shape was a classic big wave gun. The pointed nose and tail and pronounced rocker made accounting for material blowout especially critical.
Certain aspects of the project including fixture design and chamber architecture are proprietary and can’t be shown in the pictures. I fabricated three complete surfboards machined out of albizia. I developed a process to make a hollow chambered surfboard in a day, something that would take a skilled craftsman several months to produce by hand.
Dimensions: 9’ 6”
Date: Fall 2013 – Winter 2015