Rotary Box

My rotary box started out as a solution to a specific problem. Back when I was playing poker with my buddies, someone suggested that we needed a fitting storage container for our boys-night-out cigars. The box came to me in a flurry of CAD calculations and sketching and was an instant hit.

But when doctors and spouses pointed out that cigars are not necessarily the path to true happiness, the box became nothing more than a conversation piece. As if the loss of a mission statement wasn’t enough, it slowly began to bind, warp, and in general tear itself apart.

Hope springs eternal, and one day a pen collector and turner suggested that I revisit the project as a home for his most-valued specimens. Eureka! My box had a new reason for being. I enlisted the help of my brother Pete, who is a stickler for accuracy. Learning from my mistakes, he built a new box that still works fine.

As you can see, all the doors of the box open and close at the same time. One large gear turns six smaller ones—one for each door. Making the gears and drilling the holes for their axles is exacting work, but you really don’t have to be ultra-precise. It’s not like you’re making a watch!

Pete figured out the trick to synchronizing the doors: Don’t glue the gear’s axles into the doors—just make them a tight fit. This way, if one or two doors happen to lag behind the others, you just rotate them a bit by hand. Once the box is tuned, it should stay in tune.

If you get the bug to build this project, you could start with the gears, the octagonal plates or the doors. It really doesn’t matter. We’ll start with the doors, just to get them out of the way, and then move on to the more esoteric, fun stuff. A word of warning—once you start making projects with gears, you may get hooked. I sure am!

Quick Start: Deconstructing the Box

Cutting List

Overall dimensions:
Section	Part	Name	Qty.	Material	Th x W x L
Case	A	Plate	3	Red oak	3/4″ x 6-15/16″ x 8″ (a)
	B	Column	6	Hardwood dowel	5/8″ dia. x 9″
	C	Spacer	6	Hardwood dowel	3/8″ dia. x 1-1/2″
Doors	D	Panel	6	Cherry	1/2″ x 2″ x 7-7/8″
	E	Outer stile	6	Walnut	1/2″ x 1/2″ x 7-7/8″
	F	Inner stile	6	Walnut	1/2″ x 1″ x 7-7/8″
	G	Shelf	12	Cherry	1/2″ x 2-1/2″ x 2″
	H	Door axle	6	Hardwood dowel	3/16″ dia. x 5/8″
Gearing	J	Driver gear	1	Baltic birch plywood	3/8″ x 5-3/8″ dia. (b)
	K	Follower gear	7	Cherry	3/8″ x 2-11/32″ dia. (c)
	L	Follower gear axle	6	Hardwood dowel	3/16″ dia. x 2″
	M	Drive shaft	1	Hardwood dowel	5/8″ dia. x 11″
	N	Washer	1	Hardwood dowel	1″ dia. x 3/8″
	P	Button	1	1/2″ Screw plug	5/8″ o.d. x 1/4″ (d)
Notes: (a) Each plate is made from three blanks, cut in half. Each blank is 3/4″ x 3-5/8″ x 9″. (b) Make from 6″ square blank. (c) Make each gear from three 1/8″ x 2-5/8″ x 2-5/8″ blanks. (d) Cut standard plug so it’s shaft is 1/16″ long.

The doors consist of three parts: center panels (D), stiles (E and F) and shelves (G). All of these parts are 1/2″ thick; you can buy pre-planed wood or mill it yourself. All of the pieces will be quite short. For safety, do all your machining on three sets of pieces that are 15″ long.

Rip and joint the panel stock to width, then rout 1/16″ x 1/16″ rabbets along its edges (Fig. 03). Trim the panels 1/8″ extra-long, then cut dadoes for the shelves.

Make the stiles from a piece that’s at least 3″ wide (Photo 1). Rout both sides with a bullnose bit or roundover bit. Rout one side with a beading bit making multiple shallow passes. Rip both sides to final width (Photo 2).  Trim the pieces 1/8″ extra-long and glue them to the panels. Trim each door to final length.

Build a right-angle stand for drilling axle holes in the doors (Photo 3). Carefully lay out the holes and drill. Make the axles (H and L) from 3/16″ dowel rod, available at craft stores and home centers. Cut the axles to length (Photo 4), but don’t glue them in the door. Make the shelves (Fig. 04) and glue them in place.

The procedures for making the large driver gear (J) and the smaller follower gears (K) are pretty much the same. The driver is made from plywood, however, while the followers are laminated. Let’s just look at how to make a follower, since it’s more complicated.

Start by making 1/8″ blanks (see Cutting List). Drill small holes through the blanks and glue them together (Photos 5–7). For strength and stability, the grain of each piece must run in a different direction (Fig. 07).

It’s possible to lay out each gear individually with a compass (Figs. 05 and 06), but it’s much easier to work from a paper pattern. Glue the pattern to the top of the stack (Photo 8), then use a temporary-bond spray adhesive to add a backer board to the bottom. Enlarge the hole in the stack (Photo 9), then drill the gear’s “dedundums” (see Fig. 05) using a jig (Photos 10 and 11).

Cut out the gear (the “addendum circle”) freehand or use a circle-cutting jig (Photos 12-14). Remove the backer board (Photo 15). Make a mandrel from hardware store parts, then sand the gear with sandpaper adhered to a tall, wide block (Photo 16).

Saw the faces of the gear’s teeth (Photo 17). After cutting, use the side of the blade to lightly shave away any irregularities. Remove the pattern and clean up the gear (Photos 18 and 19). Glue the axles into the gears (Fig. 03).

How to Make a Plate

The box’s skeleton consists of three almost-identical plates (A), six columns (B) and six spacers (C). The columns and spacers are simply dowels that are glued into one plate and screwed into another, so the box can easily be disassembled for fine tuning. The plates are glued up from segments. (If they were made from a single piece of wood, the distances between the holes would vary unequally as the wood moved.) Let’s look at how to make a typical plate.

Mill three blanks for each plate (Fig. 08). Cut 60° angles on their ends by any means that’s safe and accurate (Photo 20). Crosscut each blank in half. Use a straightedge to align three of the pieces, then tape, glue and clamp them together (Photos 21 and 22). Repeat with another set of three pieces and glue the two assemblies together (Photos 23 and 24). Using cauls and a flat work surface for each step will produce a plate requiring very little leveling (Photo 25).

Glue on the pattern and saw the plate into a hexagonal shape (Photos 26-28). Use the gear-drilling jig (with a larger pivot pin) for drilling holes (Photo 29). Rabbet the top and middle plates (Photo 30).

 

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