Bed Tray – Design and Build

A couple weeks ago I got a message from a customer who was coming through Japan for a trip and wondered if any of my current tray offerings could be used as a bed tray. At 350mm L x 250mm W (approx. 13 3/4″ x 9 7/8″) they’re just a bit too small… plus they lack legs. So that got some gears going in my head and I started to think about different bed tray design possibilities. The customer was only going to be in Japan for a couple weeks, which combined with me finishing up some other work in the shop, meant that the timeline was tight, and I needed to come up with a design that I could fabricate relatively simply and quickly.

To get the ball rolling I started out drawing some really basic bed tray designs in Blender. Google bed tray, and you’ll see lots of designs that have a similar form to this one.

The design is basic, chunky and kind of ugly, but the point was to just start “sketching” things and generating ideas.

These first designs stuck with the standard bed tray design featuring legs that fold up underneath the tray, hence the wide frame piece which is necessary to hide the legs.

A little further along in the design evolution and I started to soften up the details by rounding out the frame a touch.

At this point the legs and round-ish tray frame don’t seem to fit together, at least not to my eye, but things are moving in a positive direction. If it was built, I think the shape of the frame, with mitered corners with some inset keys would look pretty nice.

Another issue with the above design is how to hinge the legs. I’m skeptical about wooden parts that hinge. Without a well engineered design and some solid reinforcement, they just seem doomed to break. And with hinged legs like those pictured above, so much of the stresses from putting weight on the table and racking front-to-back and side-to-side, translate directly into the hinge joint. So for this current build, I decided to move away from a design with attached folding legs. Given the timeline, I didn’t feel like I had enough time to adequately design and build a system that I felt comfortable with.

But I did explore a quick concept of one way in which I think this style could work. The key features of this hinge are the reinforced wood around the hinge, using some glued in cross grain support to strengthen the wood and resist the likelihood of splitting from racking. I also thought it’d be nice to use some sort of metal, such as brass, to fashion a bushing and rod for the pivoting parts for strength, durability, and a little pizzazz.

There are still plenty of details to explore and issues work out with this hinge joint, but this feels like the start of something that could work.

But again given the complexity of all that, I decided to explore some other options. Having the legs become a completely separate unit from the tray was one way I thought things could be simplified. And in doing so, the tray itself could become thinner and lighter in design, since the legs wouldn’t have to be tucked up underneath.

I pretty quickly landed on a leg style that I liked both visually and that seemed to offer a simple but effective method for hinging. The concept image below shows the general form I was after, but at this point I hadn’t bothered to draw the hinge itself.

I figured this design offered a few benefits. One being that I could use just one hinge joint in the center of the X where the two horizontal parts cross, and the another benefit being that I could permanently fix the legs to the horizontal parts using some really solid joinery like bridle joints. Thus reducing the weak points of the design down to just the one hinge point. I also think this design works well because once the tray is installed on top and interlocks with the legs, there shouldn’t be a whole lot of stress on the hinge itself from racking, etc.

Here’s how the design looks with the tray included. In simplifying the legs, I also reverted the tray design back to a larger version of my chouna trays, again in an effort to streamline the process. The customer also mentioned they liked the design of those trays, and I had jigs and a process worked out already, so it was a no-brainer to go that route. I also think the thinner profile frame of the tray works well with the leg design.

And now for the real deal.

I ended up beefing up the legs a touch, and made them just a hair longer, but otherwise the overall design is the same as what I drew in the computer.

I was moving fast to get this project finished, so I didn’t have a ton of time to take process shots, but I did snap a couple from planing the scalloped texture in the tray’s panel, using a soto-maru-ganna (外丸鉋).

Japanese cherry is really similar to American black cherry, but it has more subtle streaks of grey and green. It ages beautifully becoming darker and richer, and this panel should be no exception.

Here’s a shot of the finished leg structure. Bridle joints on the legs/stretchers. One stretcher is continuous, and the other is cut and joined into a little zig-zag for folding, again using a bridle joint for lots of glue surface and strength. I cut all the joinery for the leg structure by hand. With every joint involving some sort of angled shoulder, I found it easier and quicker to just cut things by hand than to try and work out jigs and fixtures for cutting with machines.

Hinge open….

and hinge closed…

Here’s how the legs look when folded up.

The legs are notched to fit into the corners on the underside of the tray. The tray nestles down nicely onto these notches, which prevents the legs from closing and keeps the tray from sliding around.

A big thanks to the customers who asked me to build this. I really enjoy design/build challenges like this. This project was also a reminder of how beneficial Blender has become to my process. Being able to quickly explore different designs and show the customer more or less exactly what they’re going to get is really awesome.

Thanks for reading.