Was making a Christmas box today out of a scrap piece of purpleheart I had kicking around the shop and
it occurred to me that how I derived the box size and cut might be of interest. I hate to waste good material. So when you're faced with a task like this, where you have a piece of stock and need to make the biggest possible box from it, you should know the trick for using every bit of your material.
This relationship works no matter what the size of your stock is. You'll make the largest possible box from it for either box joints or mitered joints. There is a tiny bit of waste for a butt joint box, but I don't make that kind of box.
(Refer to the drawing at right) Since the width of the stock sets the width of the box, by knowing the width we can immediately determine the width of the end pieces. Subtracting this amount from the length of the board leaves us with the wood to make the top, bottom and sides from. So we take the remainder and divide it into thirds since the top, bottom, and sides are all the same length. Finally we notice that the tallest we can make our four sides is half the width of the board. We divide the initial end material and one of the remaining thirds in half lengthwise. At this point we have our layout as shown.
Depending on the joint you are going to use, you may have to adjust the width of the side pieces down to the next increment. For miter joint boxes you can just use the dimensions shown. But for box joint boxes you need to be on a 2x multiple of the bit width. So if you're going to have ¼" box joint fingers, your maximum width can only be an increment of ½" (2x of ¼" cutter). Since our width is more than 4" we pick 2" as the largest multiple of 2x our bit size possible.
So for my little project for today my piece was a hair under 4½" wide and 23½" long by 15/32" thick. I trimmed it down to a final 4¼" width so I subtracted 4½" (to allow for the kerf) from the 23½" length and got 19". The 19" remaining is cut into thirds. Dividing 19" by three gives just over 6" so that became my box length. The remaining fraction of an inch was chewed up by kerf. I could have gone to 6¼" for the length, but I didn't want to cut it that fine as I needed two kerfs out of that piece and that would leave no margin for a squaring end cut. Organizing by width and rounding up to the nearest half meant that I needed one piece at least 10½" and another 12½" or totalling 23" of my 23½". Splitting the difference between the two pieces made my first cut at 10¾".
Next I ripped my 10¾" piece down into two, 2" strips. This is the largest increment of ½" that would go into the width I had. Finally I trimmed my 4¼" end pieces off and fine cut the remaining pieces at 6". This gave me all the pieces necessary for a box and essentially no scrap remaining.
You can use this relationship no matter what size your original board is. Naturally you are free to vary the dimensions to suit your taste, but this relationship will make you feel good about not wasting valuable stock!
Here the box is being clamped up. I've got eight clamps on a 3x4x6 box! Yes, I need MORE CLAMPS! In a change from my normal box this one has the bottom applied outside the sides to maximize the internal depth. At 2" it's marginal, if I inset the box it would go down to 1½" and that is just too shallow. Because of the change in construction and time constraints I biscuited the bottom on while the sides were clamping. To do this I'd precut biscuit slots in the bottom and each side to keep me in tight alignment. The pieces are in the order they grew so the grain wraps around the box sequentially.
Here you can see the box as it looked when the clamps came off.
Here you can see the completed box after rough sanding, routing, and final sanding. It's ready for me to mortise in the 95° stopped hinge for the lid. I had a pair 2" hinges but I used a single 4" hinge because it looked better. The mortising process is easily and quickly done on the router table with a couple of stop blocks. I use my ½" straight cutter and set it just proud of the thickness of the hinge.
Here are some shots of the completed box after it's first coat of 50%-50% poly-MS.
I don't have pics yet, but the box has been completed with the addition of a small mirror on the underside of the lid, blue felt lining and a brass eagle applied to the top. The red of the purpleheart, white of the mirror and blue of the lining make it a patriotic box especially with the federal looking eagle on the lid. A pair of small felt pads on the corners of the body prevent the lid from slamming and level out the top when closed.
Attaching the brass eagle was a minor pain. The brass brads were ½" long — the same as the thickness of the top. The purpleheart is simply too tough to drive a brad into so I drilled a 3/8" deep x 1/16" dia pilot hole where the three brads needed to go. I tapped them into place using the flat side of a screwdriver on the top of the brad. This kept me from beating the lid with the hammer. Although I had predrilled, the brads were long enough to dimple up the underside of the lid. But the mirror, mounted with silicone adhesive, neatly covered them up.
The blue felt lining was installed with Elmers Spray Adhesive and was sequenced to hide any gaps (bottom, long sides, short sides). The final project is lovely and will make a beautiful Christmas gift for a friend of mine. If I had to make another the spreadsheet says that I'd have to charge close to $100 for it.