Modular Bookshelf

I wanted to build a good-looking and practical bookshelf for our new apartement. Since the apartement is on the top floor, the ceiling is angular and the bookshelf had to be fitted to the wall. I decided to design it in a modular way, so it can easily be adapted to different circumstances. It took some thinking and tweaking, but I came up with a solution that works rather nicely.

There are some big advantages (in my opionion):
- You can rearrange the whole thing whenever you get tired of looking at it
- It's easily expandable (by either rearranging or building more modules)
- It creates a "living" wall of books (and/or other things)
- The modules are very light and are easy to move around, plus they take up very little space (for example in a moving van)

The modules come in different sizes (either quadratical or oblong).
The width is in every case a multiplate of the height (up to 5:1 in my case), so that the modules are stackable. There are 3 different module-heights to accomodate either paperbacks, hardbacks, binders, big books, and so on. The different sizes of books/binders demand different depths for the modules, too, which gives a really nice look to the complete bookshelf.
The longer modules (3:1 and more) need a middle panel, to distribute the weight of modules on top of them evenly.
In order to combine all these different heights and widths, I had to build 2 customized modules which have different sizes (to adjust for the height), but besides that, everything is standardized.

I wanted to build the modules as low-key and sleek as possible. There is almost no hardware needed, since all the joints are glued. The mitred joints allow for a very elegant construction (although its harder to build) and keep the whole design very simple.
To assemble the whole bookshelf I made aluminum-clips out of a U-profile. Lined with textile tape, they clamp together the modules, making the whole bookshelf stable and sturdy.

For my bookshelf I chose a 9mm phenolic resin-coated birch-plywood. This coated plywood has a very robust and nice looking surface, but it is rather expensive (about 48 US-Dollars per m2). Plywood offers the advantage of constructing this with quite thin material (9mm), and there is no real need for the coated surface besides the look.

Since I don't own equipment to cut the big boards down to size, I had the material ordered as strips of the 3 different depths I needed. Clean and nice cuts are really important, since half of the edges are visible at the end.

So the needed materials are:

- Plywood-strips (widths depending on the measurements for the modules)
- Aluminum-U-profile (to produce the clamps)
- Felt-pads for the bottom modules

The tools I used for this project:

- A halfway decent circular saw bench (with the ability to tilt the saw blade to 45 degrees)
- A calibrated try square
- A measuring tape
- Lots of abrasive paper
- A very well sharpened chisel
- 1-K PUR wood adhesive (it has to be a really strong adhesive, since the surface of the connections is quite small)
- Plenty of plastic adhesive tape

The first step is cutting the plywood-strips to the required lengths. To achieve very clean cuts, I use a piece of thick plywood as a base, on which I cut the miter joints (and even joints for the middle panel). This way I get close to no chipping at the edges.

It is very important to use arrestors, so that the corresponding pieces have the exact same length. I tend to check the lengths after every second cut, just to be on the safe side.

The angle of the sawblade is crucial, since even a half degree off can result in joints that don't fit properly. I use surplus wood to test that angle very carefully until the pieces fit perfectly.

Always take care to use the safety devices as specified! Even if it means slower progress.

The surfaces of this coated plywood don't need to be sanded, but with other materials, now would be the time to get a nice smooth surface.
To get the edges nice and smooth, I take several pieces of the same width and pinch them together with wooden bar clamps. It's easier to work this way and ultimately, it's a lot faster.

After sanding all edges like this (a very important step) I chamfer the edges very subtly. I prefer sharp edges, but still, they should be a bit chamfered.

When all of this is done, the pieces should be cleaned. All the dust needs to be removed, as not to affect the quality of the adhesion.

All the joints (inside and outside) need to be prepared with plastic adhesive tape. This technique will take a moment to prepare, but the time it saves after the adhesive has cured is substantial. Align the tape very carefully on the very edges (inner and outer edges) and do this wherever there will be adhesive (as seen in the pictures). Do the same for all middle panels by measuring precisely where they will be and then taping around the adhesive surface. The overspilt adhesive will cure on the plastic and can then be removed very easily.

Now it is time to assemble the parts by means of plastic tape. Place the pieces in the right order on a flat and clean surface and tape them together on the outside. Its very important that the outside edges are perfectly aligned so the miter joints will fit. When everything is taped together on the outside, it has to be flipped, which can be quite tricky. Now it is possible to "fold" the whole module and check if everything fits nicely.

I always do this before I apply any adhesive!

After this check, I apply the adhesive. The adhesive I use expands while curing, so not much of it is needed in these joints. If there is excess adhesive, don't bother wiping it off. PUR-adhesive is really nasty before curing and can much easier be removed mechanically after curing.
After applying the adhesive, I "fold" the pieces together and fixate both "open" ends with more plastic tape. I use a try square to check the angles and check all the corners carefully because the edges can sometime shift a bit.

Since the plastic tape is also applied for the middle panel (where one is planned), it is convenient to insert this panel at this time. I apply the adhesive on the panel's edges, spread the module a bit and put the middle panel in-between. It's easy to adjust its position because of the plastic tape, and to be sure I check it again with the try square.

When all the angles are checked again, I put some weight on top of the module so that the middle panel receives the needed pressure, check all the angles once more and let it cure for at least 3 hours (depending on the adhesive).

After curing, all the plastic tape can be removed, which should get rid of almost all the excess adhesive. The adhesive residue on the edges and in the corners needs to be removed very carefully with a well sharpened chisel. The traces of adhesive on the edge need to be removed by sanding, so that the miter joints look nice.

I chamfer the now joined edges a little bit and retouch them with a black marker. This leaves no trace on this material, but needs to be tested with every other material.

I always test the modules by trying to pull them apart, but they are really sturdy. After checking all the edges, I decide which side looks better, and I mark the less perfect side so that I know which way to assemble the whole thing at home.

I've had some practice in producing these modules, since I wanted to fill the whole wall with this modular bookshelf. It sounds like a lot of work, but by producing multiple modules at a time, it becomes quite efficient. To produce a single module takes about 1 hour (besides the curing process). Producing 10 modules will take maybe 5 hours, and the more modules are made side by side, the less time it takes.

I enjoy this project a lot, because it's practical and beautiful. Working on it is very satisfying, since all the time spent for preparations really pays off in the end.

I would be happy to read your ideas, your criticism, your opinions and your remarks on this modular bookshelf. Thank you!