Joe Harmon Design Splinter cut-away.
Joe Harmon Design is building a high-performance, mid-engined supercar from wood composites as a graduate project at North Carolina State University.
Wood will be used where ever possible, including the chassis, body, and large percentages of the suspension components and wheels. The car has a target weight of 2500 lbs and a power goal of over 600 horsepower.
They aren't trying to sell anything; They aren't trying to save the world, and they aren't advocating that everyone should drive a wooden car. This project is a scholastic endeavour in which are simply trying to explore materials, learn, teach, share ideas, and stimulate creativity.
How its done.
When many people think about wooden vehicles, they don't think high performance. They think about a canoe made of a hollowed-out log or a rickety wagon made of nailed-together planks. The Splinter, an ultra-high performance, wooden car, is not made using these construction techniques.
Essentially every part on the Splinter is made of composites. Composites like carbon fiber and fiberglass have been seen on cars for decades, but a car using wood composites to the extent that the Splinter does has never been built. Although molding composites is probably the single biggest part of what they do, building a car from the ground up involves a huge range of processes.
The processes used to build the Splinter involve wood, metal, foam or even glass.
Bladder molding is a technique used that involves the application of positive pressure to a hose or a bag. Placed inside a mold the inflated bladder applies equal pressure to the entire part, assuring a uniform glue-up. They use mostly underground rubber and cloth flexible water tubes, as they are available in different sizes and can hold up to 150psi.
The most important material they use on the car other than wood of course is glue. Glues have come a long way in the last few years, even the space shuttle uses glue to secure their exterior body panels. Thanks to their sponsors they have access to some of the industry's best. Their glues most used are PVAs, UF, urethanes, and epoxies.
Vacuum bagging is the same idea as everything else they do, apply equal pressure to the entire part to make sure the glue bonds well. With the Vacuum however, they suck all the air out of a bag that contains the part instead of blowing up a bag around it. They make their own bags that are usually part specific, some being as large as 8 feet x 12 feet.
Clamping sounds pretty self explanatory, as it is. The idea here is to place the glued laminates to a mold and then clamp the hell out of it. They have and use hundreds of clamps on nearly every part made, from pipe clamps, F-clamps or bar clamps, one-handed bar clamps, wooden hand screws, spring clamps, G-clamps, or wooden cam clamps.
Strap hold down.
Strap hold downs are something they came up with when nothing else seemed hold down tight on a mold. The hold downs are basically large sheets of industrial sand paper (used because of their incredible strength) clamped on both ends with all-thread attached. The all-thread can be fed through holes in the molds and tightened to tighten the straps around a part.
Mold making is something they do on almost a daily basis. Every part needs its own mold, even the body panels, because they are mirrored; need a set of molds for the left side of the car and another set for the right. They make many kinds of molds, including solid molds, all-thread molds, and scab molds.
Veneer stitching basically involves stitching two pieces of veneer together at their seams. Different parts need stiffness in different directions and wood only offers strength in one direction meaning sometimes they need the wood grain going vertically in one area and horizontally in another, both on the same part. They use glues, tapes and coated string to bridge the gaps.
Press molding can be used in conjunction with other types of molding, but most commonly they use presses to push together male and female ends of a mold, with the laminate in between. They use a screw press for smaller parts and just got a 100 ton cold press that should do just about anything they need it to.
Pattern following is necessary in order to create many identical parts. The molds they make are often large and have to be identical in size from one end to the other, so they make many identical ribs and span them with wood. Often there is no room for error in making their molds, and pattern following is a great way to stay precise.
Glass cutting is something they are still exploring, having failed up until now, they are exploring new options on how they will get the glass for the windshield and the windows cut to size. They have tried using diamond cutting wheels, water jets, router bits, razor scoring, and just about everything else they can think of. 5 broken windshields later this is getting to be expensive.
Machining is an integral part to making some structural elements to the car and everything they do is in house. Although they are trying to make almost everything out of wood, some metal is necessary, and all of that has to be custom made. Hunt has spent many a long night accompanied by his best friends, milling machines and lathes.
Shaping is basically starting out with a big block of material and slowly cutting away at it to get a desired shape. Nothing on the car is caved, but some of their molds are made in this way. Most commonly caved is insulation foam or pink foam; they do shape wood as well.
Metal fabrication includes welding, torching, cutting, banging, plasma cutting, grinding and yelling at metal. Most of the molds they make need quite a bit of metal to be able to withstand the huge forces they put on them. Nothing is just available at the hardware store, everything is made there.
(source: Joe Harmon Design)
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