Single Board lid?

[Josh Rudolph]

I am designing a box that is approximately 48" x 14" x 5". All components will be made out of solid wood...plywood is not an option for this build.

My initial thought was to have a single board as the lid. (I do have a source for a board of that size.)

Is there any reason I should abonden this inital design and go with a paneled lid?

Same goes for the bottom.

Also, what type of joinery would you use for this box? All methods are an option at this point.

Thanks.

[Todd Burch]

If the wood is well seasoned and generally a stable wood anyway, cut from the right part of a tree, and doesn't have any crazy grain or spike knots, you should be good to go.

What's the box going to be used for? Can't say on the joinery, from a functional standpoint, without knowing the requirements.

[Kent A Bathurst]

If it is a basic design, where the lid is hinged at the back, and is just a flat board [versus lipped, so that it "nests" over the case] then, yeah - I don't see why not. All the expansion and contraction will be at the front, with the rear of the lid remaining fixed in place by the hinges.

The thing about frame-and-panel is that the frame functions, to a degree, in keeping the board flat.OTHO - On flat-lidded blanket chests, as one example, you will often find battens on the underside to help keep the non-framed wide lid flat.

If you are reasonably comfortable with the stability of the lid board, then I vote for "Tee it up".

[Josh Rudolph]

Box will be used for storing and carrying a sculpture made by a friend. The sculpture weighs about 20 pounds with most of the weight focused on the bottom so it stands accordingly when being displayed.
I think the box will be used regularly as a transport.

Probably going to use Honduras Mahogany as the wood as I know I can get wide panels. She also wants the box to be a nice piece as it will likely be in the same proximity of the sculpture.

[Don Stephan]

As a general average, over the course of a year wood expands and contracts seasonally about 1/8", more near the coast and less in areas with less variable relative humidity. With a copy of Hoadley's excellent "Understanding Wood" one can probably find the coeficient for your mahogany and plug into the formula.

[Russell Sansom]

From my experience, I would never consider making a solid door this size. It will certainly twist and probably turn diamond in shape. There's simply nothing to restrain it. A frame, on the other hand, even if it's slight, will usually keep a big board like that pretty flat. I think one develops an eye for the size of the frame needed for a specific panel. I know our forefathers did this back when there was plenty of first-growth lumber in theses widths. But those bottoms always split sooner or later. They have no choice.
So, I go with a floating bottom and floating top for any thing bigger than a shoebox. As a bonus, making panels is a very pleasant process and they almost turn out well. It's a skill that one needs all the time for at least for the bottoms of boxes. In your case, for a sculpture, I'd try to avoid setting it on the inside bottom by putting in a shelf or ledge for that purpose. It's just always been my philosophy not to attach things to paneled backs and paneled bottoms.
russ

[Frank Drew]

I might have a different design ideas about using a one-board lid, but in my experience a really well-seasoned board, finished similarly on both sides, has an excellent chance of remaining flat. Turning diamond in shape? That I just don't get and have never seen a flat board do anything like that, if I understand that phrasing accurately.

[George Gyulatyan]

How about breadboard ends?

You could even make it a feature by using contrasting wood.

[Mike Cutler]

Josh

I think it's really a matter of the quality and grain structure of the wood. Get the right wood, Qsawn, and I don't see a problem. In fact if it were a problem I'd have it right now, as I have boards larger than that stored in my garage/shop that is unheated, and not climate controlled. The largest unsupported piece stored out there is 7'x32" at 8/4, and I have some 4/4 at 16" wide and 8'+ in length.
If the wood is suspect, you could always frame and panel the door. It's a nice design touch anyway.

[Todd Burch]

I didn't think of this yesterday, but I have <the equivalent of> a large flat lidded box in my shop, for the last 20 years. It's an 8' tall toolbox cabinet with unfinished 1X12 pine board doors. The two doors are simply 1x12 pine boards. They've been dead flat. Now, I did spend some time picking the boards, as they are mostly clear. But even so, as most big box pine is sold, they are cut from the center of the tree.

On the wood movement front, they move seasonably, as observed by the gap between the doors. This time of year, there is about a 1/8" gap between the shiplaps of the two doors. In the more humid part of the year, they touch in the middle.

I also have a smaller storage box, about 12" x 16" where I store my commonly used files. It too has a (1/2" thick) solid lid, just pine, and it too is dead flat to this day.

I've also made dozens of shoe-box sized sliding lid boxes, and I can't think of one that has had a lid warp to even a noticeable amount.

I would approach your project, as designed, with no hesitation.

[Myk Rian]

From my experience, I would never consider making a solid door this size.
Neither would I. Make a framed panel.

[Bill McDermott]

A solid top seems manageable to me, since you are already aware of the risk and will be careful about wood selection, prep and finishing. Why not give it a try? Battens on the inside of the lid should help keep it flat.
If you design with a frame and panel bottom that is the same size as the top, you can build a second bottom, taking advantage of the set ups. If the solid top goes wacky on you, replace it with the spare frame and panel piece.