Secret Puzzle Book Box

Video HERE

This project - or something like it - has been rumbling around my brain since long before the Shed was built. Sketches of puzzle box mechanisms (rather Heath-Robinson-esque) fill a number of sketch pads, but I have neither the skill nor the tools to actually make most of them!

It's difficult to write up the method I used, mainly because it was a rather fluid process and I didn't take notes... or photos along the way (yes, I will do better in future)... So here are the stages I remember, and what I've learned during the process...

1. Firstly, I picked out a box that already had a lock (much easier to build on to one that already has that mechanism) then sketched a general idea of how many working parts I wanted and where to hide the key. This box provided only one place where I could drill a hole big enough so that informed the design.
2. Then, I made a simple mock-up of the moving blocks using stirring sticks - more substantial than paper and cheaper than actual wood for a test of the sketch. Once the design works in model form I made scale templates in paper and started to cut veneer.*
3. This stage was long and tedious, I cut about 60 strips of veneer for each piece - at this stage I could have cut out the notches, but there was a substantial risk of the veneer splintering so I decided to glue them into blocks first.
4. I lined the sides of the box with masking tape and used a strip of veneer as a base then glued and stuffed in as many pieces of veneer as would fit and used the box itself as a clamp.**
5. I removed the lock and the hinges - actually they pretty much fell out in my hands - perils of buying joblots of damaged stock, but better it happens now then once the piece is finished.
6. To build up the inside of the box I added 4 layers of mahogany veneer, alternating square and mitre joints for added strength, wide enough to cover the edge of the box and sit level with the veneer blocks.
7. After cutting out the notches and leveling the pages I glued in the fixed blocks and secured them with pins through the original box and the veneer block, then stuck on another layer of veneer to cover the edges of the lid.
8. I used all the blocks to help the new pages glue in place and equalize the pressure to keep the pages mostly level. Sanding was difficult with so many thin edges, but I rubbed over the blocks to 120 grit, knowing that the paint would cover many of the rougher patches.***
9. Then, whilst everything was held together I added strips of plywood to extend the covers over the level of the pages. On the lid it was easy to stick everything together, but the bottom couldn't be completely glued so I used strips of paper to add extra glue area to hold things together.
10. Having removed the original hinges I had to build up the edges to match the new level, so I cut thinner strips, leaving 2 layers of space for the new ones to fit in on either piece. I trimmed these back a bit, but probably could have removed more to allow for smoother opening.
11. I decided to fill the cracks between the moving parts as well as hiding the joins and used a piece of acetate to create separation, which was only half successful. For future reference, add a little more PVA to the filler mix to help hold things together, and wait until completely dry before separating. When the filler was half-dry I cut along the pages to try and smooth the transitions between blocks.
12. Once the filler was dry I painted the pages with a thin layer of black acrylic, then another of darkish brown - using a cheap brush is easier to scrub into the gaps, but I didn't make too much of an effort to cover everything to give it more depth and character.****
13. For the mechanism I used a few pins to mark in and out positions, then carefully drilled away with a hobby drill between the points to make slots. (Masking tape placed over the cutting area to hold everything together and reduce splintering) I cut slots on both sides to add stability, but I suspect cutting all the way through would save a lot of extra fiddling around - and longer pins would help make it more solid.
14. Before I fixed the mechanism in place I gave the back sides of the blocks a thorough sanding up to 120 grit, then rubbed them with wax to add a little lubrication. I didn't do much to the sides of the original box... perhaps I should have. Once pinned I stuck on another layer of veneer to cover and add strength.
15. The outer covers needed new surfaces so I attached a thin sheet of ply to either side and pressed them flat overnight. The original plan was to do a pyrography design, but after testing on a scrap I really didn't like how it burned so I decided on more veneer instead with edge binding of brown paper to give it a tidy surface.
16. For the spine I used a scrap of leather, reinforced with card for a more book-style spine, then added ribbon and stained the cover edges to a matching colour.*****
17. For some reason I am yet to understand, now I decided to drill out the key holes... much sawdust and swearing ensued... and top-up painting. Now that I could access the lock from both sides I realized that the gap was a too tight for my fat fingers to turn the key - and for the key itself to turn... more hobby drilling required to cut back a bit on both sides so that the key can actually twist... and 15 minutes work with a dowel and some ply offcuts made a big novelty key with a secret.
18. To give it a more old-fashioned book-look I added a thin coat of gold acrylic to gild the pages, then added a little watered-down black to the cover edges to weather them slightly.
19. I decided on a simple felt lining - rather than a full padded one, the opening isn't very large so I didn't want to fill it with unneccessary stuff.
20. The weather wasn't particularly pleasant by the time I was ready to add finish, so I put the spray varnish on hold and went with a good coat of wax instead.

This was much more of a learning experience than I expected... as these things often are.

*As I've said before, I have a ticket to Veneer Mountain, and all my previous projects have barely made a dent. This was mainly made with scraps, plus about 5 large-ish sheets of mahogany. If you have actual blocks of wood then I expect that you can do this just the same way, but probably with less glue.
**Using the side of the box as a clamp was an ideal shortcut as I don't have any of the right kind of clamps to do it another way - this also meant that the blocks were guaranteed to fit.
***Sanding the pages could have been avoided if I'd taken some sandpaper to the individual strips, BUT I have a life and sanding 240 individual strips of veneer is not what I want to spend my time doing! Rubbing over the blocks with a piece of 120 in your fingers (not on a block) is an interesting experience and I have learned to move slowly and steadily, or spend time removing needle-thin splinters from my knuckles.
****I could have been very particular about the arrangement of the pages to create that realistic book-arc, but this is a prototype, and cutting 240 pieces of 15mm width was plenty of work for me. I like the more rustic look... and I worry about the strength of sliding blocks with different thicknesses of veneer which might not be stable for the mechanism.
*****My initial plan was to use a piece of veneer as the spine, but I had a concern for the strength after repeated bendings. Next idea was veneer strips glued around fabric... but in the end I decided on a strip of leather which would look more like an actual book when stacked on a shelf, and stand up to flexing stresses better than both of the other options. The only major problem I have with the leather is where it joins the covers. This point recieves the most strain and it shows after only a few hours where the corners have peeled back slightly. I will need to put in a stitch or something to reinforce the joint in the near future, and I will need to adapt that joint if I decide to repeat this build.

These pictures have come out a little grey, apologies, this actually has a really rich mahogany glow to it... If I remember I will bring it up in the March report so you can see the finish in more flattering light.

I have another seconds quality book box in my stash so this design may resurface in the future, although I have a hankering to try leather-effect decoupage... watch this space.