Parametric Shelf With Reciprocal Frame

Dear reader!

Please excuse my poor English skills. If you find a mistake in my guide, please help me correct it with your comments!

I made the first similar shelf twenty years ago. We moved into a new apartment and didn't have enough money left for furniture. I received a lot of 600x200 millimetres leftover particle boards from a carpenter friend, which cannot be used to make a traditional bookshelf, so I decided on a reciprocal frame. Everyone liked it, even though it was just a not-so-well-executed emergency solution. We recently moved again to another apartment, so I had the opportunity to rebuild more thoughtfully, keeping the following in mind:

- Sturdy: safety is number one!

- Durable: I wanted a piece of furniture that we could use for years.

- De-mountable: a big shelf like this needs to come apart or it will never leave the workshop!

- Practical: I can determine the size of the shelves, not the materials at my disposal.

- Cheap: the materials used were at my disposal. Therefore, I only had to spend my free time on it (186 hours).

Material requirement. The size of the wall is 4300×2700 millimetres, where I also placed a television. Thus, the amount of materials used:

- 1900×300×20 millimetres, pine wood edge glued board 2 pcs

- 700×300×20 millimetres, pine wood edge glued board 53 pcs

- 480×300×20 millimetres, pine wood edge glued board 3 pcs

- 460×300×20 millimetres, pine wood edge glued board 8 pcs

- 240×300×20 millimetres, pine wood edge glued board 4 pcs

- 4×55 millimetres screw 272 pcs

- M6 insert nuts 16 pcs

- M6 adjustable furniture feet 16 pcs

- Some kind of wood finishing product

- Hooks 7 pcs

- Dowels 7 pcs

Tools:

- Miter saw

- jigsaw

- hand router

- flush trim bit with insert knives

- Flexible Template for Routing

- screw driver

- countersink drill bit

- sanding machine and sanding net

- brush

The above applies to the simpler, faster but more expensive version. You buy the edge glued board ready, and the wood finishing product also costs a lot of money. The cheaper version requires more tools and time. You also need:

- lots of leftover lumber (to make the parts)

- epoxy resin

- linseed oil

- many candles

- glue

- clamps

- planer (minimum 310 millimetres)

- table saw

- cauls

- flatiron (is not steamer)

- hot air gun

We have a lot of books, most of them are paperback novels. Their average size is 200 millimetres. Therefore, the smaller shelf opening had to be made higher than this, so that the books could be easily moved. I sized the larger opening to double this so that the shelves are in line. To the resulting 660 millimetres I added twice the thickness of the shelf and got 700 millimetres. (This size is of course affected by the thickness of the material I used.) The shelves have two types of wave patterns, and on top of that I needed 1/3 and 2/3 length parts. To see through the chaos, I used Tinkercad. A real do-it-yourselfer uses linux. I don't like playing in a sandbox, Fusion 360 was not available to me this time :(.

I made the template from MDF because its structure is homogeneous and a clean milling surface can be created. The steps are as follows:

- I screwed a stop bar 310 millimetres from the long edge of the template

- I marked the center line, perpendicular to the stop bar

- I marked 240 millimetres on the center line

- I marked a straight line 580 millimetres from the center line in both directions, perpendicular to the stop bar (I attached the end of the shelf to this)

- I marked 260 millimetres on these lines

- I marked a straight line 350 millimetres from the center line in both directions, perpendicular to the stop bar

- I marked 300 millimetres on these lines

- I marked a straight line 120 millimetres from the center line in both directions, perpendicular to the stop bar

- I marked 260 millimetres on these lines

- I placed the central hole of the flexible template on the center line and aligned the edge to the 240 mm marking, then screwed

- I fitted the flexible template to the straight 260 millimetres mark marked 120 millimetres from the center line (symmetrically), then screwed

- I fitted the flexible template to the straight 300 millimetres mark marked 350 millimetres from the center line (symmetrically), then screwed

- I drew the resulting arc on the MDF sheet and removed the flexible template

- I placed the outermost hole of the flexible template on the center line and fixed it in the formed screw holes

- I fitted the flexible template to the straight 260 millimetres mark marked 580 millimetres from the center line (symmetrically with the previously created curve), then screwed it

- I drew the resulting arc on the MDF sheet and removed the flexible template

- I repeated this on the other side as well

- along the drawn line, I cut off the excess with a jigsaw

- I fixed the flexible template in the created screw holes and created the final curve with a milling machine

I am in a lucky situation because I have a workshop where I did the work. In this workshop, years ago, I had to make one-way pallets from 30 cubic meters of pine lumber. There was, of course, a safety margin in this truckload, so I saved the better quality lumber for other uses. The shelves were made from some of these. I cut the slats to the appropriate length (730 millimetres) with a circular saw, and then created the cross section with a combined planer. Ideally, the edge strip is wider than 60 millimetres, because after milling, the gluing lines are not visible. I saved on the material, so I glued it as shown in the pictures. I used clamping cauls for edge gluing to speed up the process. I created the thickness with a thickening planer and then cut exact lengths with a table saw according to the instructions in the introduction.

With the help of the previously prepared template, I drew the curves on the parts, then cut off the excess with a jigsaw. I refined the waveforms with a handles router machine. After that, I treated the shelves with Clorox, then filled the knots and cracks with a two-component water-clear epoxy resin. I taped the underside of the cracks that went through with painters tape to prevent the resin from leaking out.

I made holes for the screws on the parts, 230 millimetres from the short edge. I started assembling the shelf system based on the Tinkerked drawings. I made a 220×220 and a 460×220 millimetres spacer from MDF. With the help of these, I drilled the parts together. The holes must be countersunk, because the head of the screw breaks the wood nastily. I placed the 1900 mm shelves last so that I wouldn't miss the location of the holes. I numbered the parts, on their rear edge, at the junctions. I have 118 nodes. I disassembled it and created the place for the nuts on the lower vertical parts, where I later put the adjustable legs. I also cut out the place for the parquet skirting board with a Japanese saw. I placed the hanging tabs on the upper vertical parts. and I created the cable hole on the long shelf.

I prepared the shelves with a Mirka orbital sander and 120 sanding net. Thanks to the Clorox treatment, the wood fibers stood out from the surface, so a second sanding was not necessary. As a primer, I applied linseed oil with a soft cloth. After that came the candle wax. Why did I choose this? Because if it gets damaged later on, the surface can be easily repaired. In addition (and on top of that) my wife is a marriage registrar and we have a lot of candles left over from wedding ceremonies. I have tried many methods of applying candle wax. The following method worked for me:

- I melted the candle wax on the surface with an iron (not steam)

- I spread it on the surface with an iron

- I leveled the candle wax with a hot air blower

- after it cooled down, I removed the excess with an orbital sander and 120 net

- I polished it with a vibrating sander and a densely woven soft carpet cut to size

The surface is suitable if the drop of water rolls off it without residue. Achieving this requires a lot of patience, a lot of time, and the experience gained in the process. My acquired experience is as follows:

- not all candles are suitable for surface treatment (wood finishing). For example, IKEA Jubla is not very good

- the pigmented candle only slightly changes the colour of the surface

- if the wax layer is too thick, the surface will be bubbly or orange-peeled

- abrasives clog quickly

The sanding mesh is a solution to the latter problem, because it can be regenerated. Take a paper box and remove the bottom and top. As shown in the picture, keep the hot air blower and the orbital sander about 30 centimetres apart. Turn both to the lowest setting and move the hot air blower slowly as if you were drying hair. In this way, the wax melts in the mesh and precipitates due to the rotation. That's why the box is needed, as the warm wax splatters. The operation is dangerous for the machines and for your health. Therefore, everyone should do it at their own risk.

We live on the eighth floor of a flat, so I didn't need to test the load capacity of the walls. I simply measured where the concrete rebars and electric wires are located. I did the assembly by using the Tinkercad drawings, but even so, I missed the location of two parts, but I managed to correct it in time. I didn't hide the screws on purpose, most of them are covered by the books. After placing the books, I made smaller 460×120 millimetres shelves and 220×120 millimetres consoles to make better use of the space in the larger openings.

The bookshelf was assembled in one morning. In the afternoon, when my wife came home, she was very happy that her much-loved books could take their rightful place. While we were arranging it, it turned out that the long shelf was bending 7 millimeters under the heavy weight. That's why I supported it behind the television with two slats. Everything is perfect now.