Bending Plywood for a Piano Table
There are lots of methods for handling curved work–steam-bending, band sawing sections out of hefty timber, and bent lamination, to name just three. For a current commission, I’m using a fourth: a relatively lightweight frame with a skin of bending plywood.
The job is one of the more unusual I’ve undertaken in my 35-plus years as a maker of custom furniture and cabinetry: a removable tabletop that will transform a small grand piano into a dining table. Why would anyone want such a thing? you may ask. My clients, an artistic couple, live in a compact house. Their front door opens directly into the living room, which leads into the dining room and thence to the kitchen. Each of these spaces is small; there’s no reasonable location besides the dining room to house the piano, which one of the clients, a professor of music, plays.
On my first visit to discuss the job, they told me that in the year and a half since they’d moved the piano into the house, they hadn’t friends over for dinner. It was time to remedy that. The conception of this piano top table is theirs; I just figured out how to make it.
I started by tracing the outline of the piano’s lid on the underside of a sheet of 1/4″ maple plywood. Then I cut a piano-shaped base out of 3/4″ cabinet grade plywood, following the outline of the lid but about 1-1/2″ in from the edge so that the weight of the table top would fall in line with the piano’s case. To minimize the weight of the table top, I traced this outline at a distance of 1-1/2″ from the outside edge using my Crucible dividers, filled in the outline with pencil, and cut it out with a jigsaw. I cleaned the whole thing up with a spokeshave, plane, and rasps.
Next, I traced the shape of this base onto the other half of the 3/4″ plywood sheet and made a replica using a jigsaw followed by a router fitted with a pattern cutting bit.
Between these, I sandwiched three struts of 1″-thick quartersawn oak that will hold the solid wood table top flat while allowing it to expand and contract across its width.
After gluing the assembly together, I made a skin using 1/4″ bending plywood. I used the Columbia Forest Products brand because that’s the brand carried by my primary sheet materials supplier, Frank Miller Lumber; I appreciate this company’s products especially because they are made in the United States and use a soy-based, formaldehyde-free adhesive.
After cleaning up the basic frame, I ripped a sheet of 1/4″ bending ply into 3″ strips. The plywood conformed readily to the piano’s curves; the manufacturer says it will bend readily down to a 12″ radius. I’ve found that it will even bend (to a limited degree) in two planes for work involving compound curves. The creative possibilities using bending plywood are huge.
But back to the job at hand.
To minimize the appearance of the seams, I started with the nose (the front part of the curved top), applying glue to the top and bottom framework and fastening the bending ply in place with lots of clamps.
Next, I fitted the two side pieces and glued them in place. To finish up the skin, I added a piece of 1/4″ plywood to the keyboard end.
To trace the 8″ overhang from the original template onto the top, made of curly ambrosia maple purchased from one of my local suppliers, RRAW Rough Cut Lumber, I used an old pair of trammel points with a pencil at one end. Trammels are useful for cases such as this one, but you have to hold the bar perpendicular to the outline you are tracing, or you’ll get an inaccurate shape. I repeated the tracing three times, checking and correcting the outline as I went.
– Nancy Hiller
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