PBB contributor and composites expert Dan Newland sent photos of a carbon fiber piano hinge he installed in one of his restoration projects. Called Carbinge, the product was originally designed and engineered for use in airplanes, hence it had to be lightweight and strong, so it has qualities that builders of high-end boats also appreciate.
The hinges are marketed by Leading Edge Composites in Port Hadlock, Washington, owned by John Barrett. A dentist by trade, Barrett is a former fighter-jet pilot who served in the U.S. Navy. He now privately flies a 1975 Beechcraft five-seater and a slick Lancer IVP, a 300-mph kit plane that he built himself and uses as a showcase for Carbinge.
Unlike metal piano hinges that must be fastened to a substrate, Carbinge is bonded in place. “That’s a faster install and stronger than attachments with multiple screws,” Barrett said while showing off the Carbinge installations on his plane’s curvaceous engine cowlings. “Besides, the hinges are lighter and more durable than those made of aluminum, and bonding avoids the risk of surface scratching, which makes them ideal for visual pieces like hatches or cupboards in boat interiors.”
The hinges are 4‘ (1.22m) long, 0.196“ (5mm) high, 2.3“ (58mm) wide when opened, and employ a 0.080“-diameter (2mm) stainless steel pin; other pin materials such as carbon fiber are available. They weigh 6.45 oz (183 g), roughly a third less than same-size hinges made of extruded MS20001-5 aluminum, not including attachment screws and backing plates in the substrate. Carbinge also is flexible enough to be bent into a pretzel for show, which means it conforms well to curved surfaces. The pin’s vibration-proof keeper screw is installed from the outside with a hex key. Carbinge’s sheer strength is rated at 3,000 lbs (1,361 kg) per lineal foot (0.30m) with a sheer load limit of 6,000 lbs (2,722 kg) per lineal foot. Published data attests no detectable wear or breakdown after 1.5 million cycles.
Barrett’s now-deceased former business partner, Bill Garrett, at some point was the landlord of Pete Langley, who owns Port Townsend Foundry and produces the carbon fiber blanks from five tapered layers of 5.78-oz/sq-yd (196-g/m²) carbon prepreg with 90° weave and a 260°F (127°C) cure temperature. Afterward, Barrett flies them across the Salish Sea to be waterjet-cut at Cutters Inc., in Bellingham, Washington.
Regarding the installation, the Carbinge product information sheet states: “These hinges can be trimmed easily with any carbide blade and can be shaped and/or smoothed either with a file or with sandpaper. Recommended attachment procedure to any composite surface is to thoroughly sand all surfaces to be bonded removing all shiny areas with 50- to 250-grit sandpaper. Clean the surfaces carefully with Methylene Chloride or acetone. Use Hysol or other brand(s) of high peel strength adhesives for bonding following manufacturer’s directions for use of these materials. Use of a high peel strength adhesive will give stronger results than epoxy/flox. Be sure to keep the bonding material out of the working parts of the hinge.”
Newland explained why he used Carbinge carbon fiber hinges for two halves of a V-berth cover that fold upward: “I have used these hinges for several projects to solve a common problem with thin-skinned composite parts: how to attach hinges without drilling, adding compression posts, filling and screwing in metal hinges. Compare this to drilling and filling hundreds of holes for metal hinges that are far heavier, or having to make cutouts with flanges for doors that have to be removed, then filling in all of the exposed core, in this case Nomex honeycomb. I also used a small piece for a hinge on the engine box. Because it’s carbon fiber, I primed and painted it with gloss—far better than dealing with metal.”
Leading Edge Composites, P.O. Box 428, Port Hadlock, WA 98365 USA, tel. 360–301–1066, email@example.com.