Secret Changeable Code Box

I had such great response with my Secret Code Book Puzzle, https://www.instructables.com/Secret-Code-Book-Puz... which had an electronic locking system, that I decided to build a mechanical version in which the code could easily be changed. I borrowed the cam locking system from member "tdonoclift." You can check his out here: https://www.instructables.com/Puzzle-Box-With-Cha...

This is easy to build with basic woodworking skills and there are many code combinations which can easily be set by loosening the cams and re- setting the dials.

You may well have a box that will work for this, but you will have to add a ledge to the front edge as this allows the cams to engage and lock the box.

I built my box from scratch and the dimensions are not critical, except for the locking edge.

I used 1/2 inch pine for mine, with a 5x7.5 inch bottom, front and back- 8.5x3.5 inches, sides- 5x3.5 inches.

The ledge is 1x7.5 inches.

I made the top of white PVC, the type used as outdoor construction moulding. It already had an embossed woodgrain and is dimensionally stable. I didn't want the lid to warp, as pine tends to. MDF would also be a fine choice. I sized it 8.75x 6.25 inches. This allows for a .25 inch overlap at the front and a light overlap at each edge.

As can be seen in the pictures, I used simple box construction, with butted edges. Wood glue and brad nails hold it together.

As can be seen in the photo, the ledge goes at the top of the opening edge of the box, as is being indicated by the pencil point.

Sanding the box greatly enhances its appearance. I painted mine white to match the lid.

I decided to use available knobs for this. (I hate to buy anything) Mine were the type used as adjusters on woodworking machinery and are available at any woodworker's store. Other sources are appliance knobs from stoves or washer/ dryers, etc.

I epoxy-ed .25 inch dowel to each as an axle to turn the cams.

I cut 3 wheels from .25 inch Baltic Birch plywood with a 2.25 inch hole saw.

3 spacers were cut from the same material as the ledge- half inch pine, using a 1.25 inch hole saw.

Most hole saws have a .25 inch centre drill which works perfectly for the axles.

The plywood wheels were made into cams by measuring back .25 inch on each one and marking a chord, then cutting it off as seen in the photo.

Collars were then prepared. Find 3 wood screws that are long enough to go through one side of the collar and into the centre. File the point off of each screw. This will allow you to tighten the collar to the axle and not destroy the axle in the process.

Drill through one side of each collar with a drill bit slightly smaller than the screw diameter. Countersink each hole as seen in the photo then install the screw. Make sure the screw penetrates the centre hole but don't tighten.

Glue each collar to each cam with wood glue. I temporarily inserted a .25 inch bolt in each to maintain alignment, Do not use dowel for this as it will stick to the cam and not be removable.

You'll need 2 washers for each cam as spacers. Also a hinge for the box. I used a self closing flush mount cabinet hinge.

By careful measurement, decide where the 3 holes will be located for the Knob/ Cam assemblies. I left a .25 inch gap between the flat part of each cam and went from there. You have to leave room for the cams to clear the front ledge so measure carefully. Drill these holes slightly larger than the dowels.

I decided to go with 8 knob positions so I made a cardboard template, placing it over each hole and marking the 8 positions with pencil, then drilling them with a .25 inch Forstner bit. I set my drill press so the bit would only slightly penetrate. Alternatively, you could use a punch, or anything that can make an indentation.

Because It was the easiest thing to do, I used a colour code. I simply used a Q-Tip to apply different coloured paints in the same sequence for each position.

I installed the hinge next.

Install each knob assembly. Use a washer between the knob and lid and between the lid and cam on the underside. (Important, as this allows each cam to clear the ledge. You may have to go with 2 washers on the underside if the cam doesn't clear the ledge ) Install the cam and spacer assembly. Set each knob to a colour. Make sure the flat part of the cam is parallel to the front of the box and tighten the screw.

To change the code, loosen the screw, turn the knob to the desired colour and re-tighten.

That's it, your box should close and lock. Make note of the colour code sequence in case you forget it!