Bending Plywood for a Piano Table - Popular Woodworking Magazine

Bending Plywood for a Piano Table

 In Shop Blog
bending plywood

If it looks like a piano…

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.

bending plywood

Sandwich making. I notched the oak struts so the top plywood outline would snug down into them. The struts are integral to the assembly.

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.

bending plywood

Rip the bending plywood as you would any sheet material of similar thickness. Just be sure you use a riving knife to prevent kickback, and hold the sheet firmly to keep the spaghetti-like material flat on the table.

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.

bending plywood

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.

bending plywood

The shaped portions of the assembly have their skin. Time to affix the facing to the keyboard end. While waiting for the glue to dry, I milled the boards for the ambrosia maple top and joined them in pairs. This image shows the final glue up, made possible by 9-foot-long pipe clamps.

bending plywood

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.

bending plywood

Nearly ready for finish.

bending plywood

Black and white. The base assembly has one coat of black satin paint. I’ll apply one or two more to get a completely opaque finish that should make the base disappear, in effect creating the impression that the ambrosia maple top is floating.

– Nancy Hiller


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Showing 4 comments
  • earthartinc

    Like your method of lighting up the support base, quite clever. I wonder where they will store this when not on top of the piano? Look forward to part duex, the finish and install pics!

    • Nancy Hiller

      The clients have said the top will be on the piano most of the time. When not there, it will be stored in the basement. I have mentioned the importance of humidity control.

  • pmac

    Hi Nancy,
    Neat idea. I have a question and a couple of follow ups depending on your answer: Does the base overhang the edges of the piano top (like the lid to a jar) to “lock it” in place to keep it from sliding around on the piano when it gets bumped?
    If “yes”, did you have to allow for wood movement of the piano top within the base?
    If “no”, how do you keep the new table top and base from sliding around on the piano top when it eventually gets bumped or someone pushes away from the table at dinner?
    Thanks
    Patrick
    PS A follow up post with photo of it installed would be nice to see.

    • Nancy Hiller

      Patrick,

      Great question. The base will not overhang the edges of the piano, but will sit on the lid with the weight transferred through the bottom layer of plywood onto the piano’s casework, i.e. the cabinet sides, if you will. My clients and I have been working on the assumption that diners at this table will be careful, knowing that this is no ordinary table; aside from other obvious features, the seating will be higher than normal because the new table top will be at bar stool height. The solid top is not lightweight, so we had been planning to use thick felt pads to protect the piano lid, thinking that the weight would keep things stable. However, now that you have raised this point, I am going to look into the availability of padding material with more grip. I will do a follow up post in a few weeks; it will contain some further information about the table’s making. 🙂

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