The Frustromantic Box, Part 2: Assembly

The Frustromantic Box is my implementation of Mikal Hart’s Reverse Geocache Puzzle.  In Part 1 of this series I gave an overview of the project and its parts list.  This post describes how I cut the pieces and put them together.

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I wanted the box to be 1’x1’x5 1/2″, with a 3/4″ lid. I chose those dimensions for convenience, but it turned out to be a pretty good fit for all the internals. If I’d made it any smaller, things would’ve been pretty tight.

The final product was made from cherry and birch veneer plywood, but I built a prototype first out of pine and fir. To reiterate: if you’re a novice woodworker like me, a prototype is a very good idea. I still wasted about $50 worth of cherry, but it could’ve been a lot worse.

Both the lid and the box are composed of four “edge” pieces. Each piece is one foot long, which means that when you account for the kerf of the saw blade, a 4′ length of wood isn’t quite enough. So I went with 5′ lengths and had a bit left over. I used the extra for the drawer facade and to test the stain on.

Both the lid and the box are assembled with mitre joints. The lid uses edge mitres, much like a picture frame. The box uses face mitres. All joints are reinforced with biscuits. I chose this type of joint because I figured it would be strong enough if I reinforced it (so far, so good) and because I didn’t have the time, ability or equipment for a more complicated joint.

Before I cut the mitres, though, I cut a rabbet in each piece with my router. The rabbet on the box pieces will form a pocket for the bottom of the box to fit in. The rabbet on the lid pieces will hold the “instrument panel” – the LCD display, power button and GPS sensor. I don’t have a router table, but this wasn’t a problem except for the very ends of the stock, where the router sort of rounded the corner a little bit. Since I was using 5′ lengths, I just trimmed about 1/8″ off each end after I finished to square them up again.

Note the rabbet dimensions – they’re different between the lid and the box. The 1/2″ by 1/4″ rabbet on the lid means that the panel will overlap the lid by 1/2″, which will gives a lot of surface to glue on. The 1/4″ depth means that the 1/4″ birch ply will be flush with the lid. For the box, the 1/2″ by 3/8″ rabbet means that I’ll have to double up the 1/4″ ply for the bottom – I think this will make the bottom a little more sturdy. The 3/8″ depth goes halfway through the stock – it doesn’t give a lot of surface to glue on but combined with the 1/2″ height it should be enough.

I cut the mitres in two steps: first I cut 4 1′ pieces out of the stock, then I cut the mitres in each piece. It seemed easier that way. I found that it’s more important that the pieces are exactly the same length, instead of exactly 1′ each. Even a small change in the length of each piece will make the box noticeably out of square. Finally, make sure that your mitres are all pointing the right way! The outside edge or face must be 12″!

Once the mitres were cut I began work on the drawer. The easiest thing for me to do was to get a couple of wooden boxes from Ikea and “repurpose” them. The drawer itself is called a “MOLGER” (love those Ikea product names) and the “shell” that holds the drawer is called a BJURÖN. The shell is a little too wide for the drawer, so there’s more wiggle room than I’d like, but it works. It’s also much taller than necessary, but it provides a convenient mount point for the lid servo.

I picked one box piece to be the “front”, cut a notch in it that matched the height of the drawer (plus the width of the rabbet) and cut a piece of cherry for the drawer’s facade. Since I cut the rabbet first, and had about 12″ left over, making the facade was really easy. I’m not 100% happy with how it turned out because the wood grain is totally inconsistent with the rest of the box, but I don’t know how I could’ve avoided that.

I chiseled a small niche in one of the box pieces to mount the IR sensor. In Mikal’s project I think he extended a barrel jack through the side of the box to use as a “back door”. I originally thought that it would be neater to use an IR sensor, and then trigger the backdoor with a remote control. In hindsight, Mikal’s solution has the very great advantage that he can activate the back door even if the batteries are dead. Wish I’d thought of that – d’oh. The IR sensor sits in the niche, mounted in epoxy glue. I drilled a small hole in the niche through to the exterior of the box, and filled the hole with epoxy as well. It’s very hard to tell that there’s anything there at all – I don’t think my wife’s even noticed it.

Finally, I used a biscuit joiner to cut niches in each mitre and assembled the box and lid pieces with biscuits and glue. I did a lot of dry-fit testing to make sure that everything lined up, and I used a couple of Lee Valley speed clamps to apply pressure evenly on all corners.

My choice of hinges made assembly very difficult, because I can only open the lid to about 45 degrees. Because it was such a pain to assemble, I didn’t attach the instrument panel to the lid or the plywood to the bottom of the box until the very last step. Using regular hinges and a proper illuminated pushbutton switch would have made this part a lot easier.

Here’s a .zip file containing the SketchUp plans shown below. Please note that the drawer dimensions are approximate.

Continue to Part 3: Electronics
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