36 Glorious Plies

I put the finishing touches on our <a href=/pictures/20050117-bed/>new bed</a> today. It was inspired by the <a href=http://www.dwr.com/productdetail.cfm?id=0874>Leggero Bed</a> from <a href=http://www.dwr.com/>Design Within Reach</a>. All in all it was a fun project, with very little monotony or frustration over the project.

This is a simple platform bed. The platform is made from 1/2" plywood, and has no heavy bracing to counteract flex caused by a load (ahem -- about those 20 lbs I've gained since getting married...).

The secret of this bed is the bowing of the "slats". The slats aren't pieces on their own -- they are created by cutting slices in the plywood sheets, starting 6" in from one edge, and stopping short 6" from the other edge. So the net result after cutting is still one piece of wood, just with some parallel slices in it. A small block of wood is attached to the middle of alternating slats to create a bow-up/down/up/down pattern across the slats. This makes it nearly impossible for the bed to sag along its length (I still think it's magic).

This design is really neat, since there is a minimum amount of materials used, and the result is extremely strong.
It's a lot like an airplane in this regard, and thus increases the cool factor a lot for me.

The platform is attached to two "runners" that run the length of the bed. The runners each have two short legs attached. I can lay in the middle of the bed, and there is no noticable flex in the slats or the runners -- this shows the strength of this "bowed" construction.

I designed the headboard differently than the DWR Leggero bed. While their headboard is a smooth piece, I thought the bowed construction was too cool to hide under the mattress, so I worked it into the headboard design. The headboard fits into a slot cut in one of the platform sheets.

Another driving force in the design was to use the "end grain" of the plywood as much as possible. 1/2" Baltic Birch is made of 9 plies of birch, with no voids. Lovely stuff. There are some pieces of the bed that are made from 4 layers of this plywood, making for 36 glorious plies! I wanted to show this as much as I could. The supports under the platform and the legs are built so that you can see as much of this as possible.

Here are <a href=/pictures/20050117-bed/>pictures</a> of the bed.

(Nerdy wood shop stuff follows....)

Here are the materials I used to make the bed:

<ul> <li>2.5 sheets of 1/2" baltic birch plywood (beautiful stuff -- 9 plies and no voids. This is what skateboard decks are made from) <li>20 or so 1/4" x 2" machine screws with a countersink head <li>20 or so 1/4" washers <li>20 or so 1/4" nylock nuts <li>6 feet or so of 1" x 1" maple <li>3 cans of Jasco Black Walnut danish oil <li>1 tin of Howard's Citrus Shield paste wax </ul>

Total materials cost was less than $400, with the plywood being the biggest chunk of this at about $320. Pretty good deal, considering DWR wants $1700 for the Leggero bed.

I had the guys at <a href=http://www.southernlumber.com>Southern Lumber</a> rough-cut the plywood according to a drawing I brought in. They have the right tools to do this easily -- cutting a 4x8 sheet of plywood is a clumsy and dangerous job for my tools at home. They have a radial arm saw that can cut across the full 8 foot length of a piece of plywood. For $5, how could I argue?

I had them make the following pieces from the plywood sheets:

<ul> <li>(2) 66"x43" pieces for the bed platform <li>(1) 66"x27" piece for the headboard <li>(8) 96"x2" strips to make the runners under the platform and the feet </ul>

The first thing I did when I got home was to glue up two stacks of the 2" strips for the runners. There were four strips in each stack. The stacks really looked cool -- 2" square profile with 36 layers of wood. I spread an even coat of glue between each piece, and clamped 'em up overnight. The next day, I ran each edge of the laminated stacks through the table saw to clean up the edges, then cut them to length on the sliding compound miter saw.

The next step was to build the headboard and platform pieces. I contemplated how to do this -- I would have to accurately position the piece over the fully lowered saw blade, turn on the saw, then raise the blade up through the plywood. I'd then have to push the piece, making the cut. I'd have to stop the cut short of the end of the piece accurately, lower the blade back into the saw body, then turn off the saw.

To help make the cuts accurate, I built a long (7 foot) extension for the saw fence, with pieces attached to the ends of the extension to stop the plywood in the right places. So the process was: position the fence, push the plywood against the fence and against one end-stop, turn on the saw, raise the blade up through the wood, push the wood to the other stop, lower the blade, and turn the saw off.

Once I made the jig, it was pretty straightforward to cut all the slots. I alternated between 2" and 3" slot widths on the platform part. The 2" pieces get "pushed down" by the spacer blocks. Since they're slimmer (weaker), they'll be pushed down more than the wider pieces are pushed up, making the surface the mattress sits on flatter.

After this, it was a matter of positioning the platform pieces on the runners (laminated pieces) and drilling holes and countersinking for the screws, washers, and nuts.

After a bunch of sanding (see the <a href=http://nobot.2y.net/stories/?i=109>table article</a> to review my love of 3M's "3X" 400 grit sandpaper), I applied the Danish Oil with a paint roller, which made fast work of what could have been a tedious job -- well, getting the oil in the 3/16" wide slat-slices was kinda tedious.

Two coats of the oil, with liberal rubbing-in and rubbing-off of the excess, and it was ready for the wax after a day of drying.

As I found with the table I finished last week, Danish Oil + Paste wax is a great combo for a really nice finish. Both go on easily, and both are extremely hard to screw up. Compared with polyurethane (goes on tough, super easy to mess up) it's a winner. I think the only case where I'd look to polyurethane would be on a table that saw lots of use and liquids (e.g. dining room table).

After two coats of wax and several hours of drying time, we moved the new bed into the bedroom. It looks really nice with the wood floor and the other stuff in there. With the mattress, sheets and blankets on it looks like a real bed!

So all in all, a fun project -- a unique design, very little materials, and a cool bed that will hopefully last us a long time.