My friend always wanted to build a chair made of wood, but for a long time did not know how to lay a construction without wobbling and wobbling. Above all, he had great respect for the firm connection of the seat and backrest. Professional carpenters work there with glued cones, which he did not trust. Then he saw in a photo a collapsible chair, in which one manages without tapping and has the additional advantage that it can be taken apart like a folding chair to save space in the corner. He then rebuilt it, but with a wooden backrest.
Step 1: Cutting Parts
From pinewood slats 21 x 33 mm (even more noble is it with oak) the four legs produce: 2 pieces in 520 mm length for the front, 2 pieces in 700 mm for the rear. In addition, from slightly thinner 15 x 33 mm strips, cut a total of 15 x 400 mm cross pieces for the seat and backrest. When all parts have been laid down in order, you can see at a glance whether all the lengths are right.
Step 2: Assembling
Round off the ends of the legs with a jigsaw and finish with sandpaper.
Provide the 9 cross pieces for the back 10 mm before the end with a 4 mm drill hole. The other 6 cross pieces for the seat each 32 mm from the end of a hole. Treat the holes with a driver so that the screw heads can be retracted later. Then all edges with sandpaper break (round off). Although the grinding work costs some time, but prevent someone later splinter breaks. The whole furniture feels more comfortable.
Mark the two longer legs 70mm from the lower end and fix the first of the cross pieces with screw and glue. Put the second cross piece on the other side 155 mm from the lower edge. On the same side finally mount the third crosspiece at the top. Pay attention to the squareness. Turn
the workpiece over again and place the rungs for the back rest starting at 100 mm from the top with a distance of 15 mm each on the side that has been worked first and then fix them with glue and screw again. For even distances and parallel bars, I could just insert one of the cross pieces upright as a gauge, because the bars were yes 15 mm thick. The finished backrest from the side. The back and a single cross piece sit on the side in the picture above, two more cross pieces opposite.
The seat works in a similar way to the backrest, making it easier to handle. A special feature here, however, were the bottom beveled legs, which are needed for a stable stand. I used a bevel, an adjustable angle that was set to a 3: 6 ratio. Then just tear off the bevel and cut it with the jigsaw. The first cross piece of the seat flush with the front edge and the next 270 mm from the edge glue and screw. Attention: Pay attention to a projection of 22 mm each side! It results from the used bar thickness of 21 mm plus 1 mm for the free play of both chair parts. Install the remaining cross pieces evenly distributed on the seat. If
you have done everything right with the 22 mm projection, the seat can now be inserted neatly into the part of the backrest without jamming.