7. Computer-Controlled Machining

Group Assignment

Individual assignment

This week, I decided to create a chair inspired by the A-CHAIR by Austrian industrial designer Thomas Feichtner. His style is characterized by sharp geometric shapes, a balance between functionality and aesthetics, and an innovative approach to structural solutions.

I started the drafting process in Rhino, following the main ergonomic dimensions but slightly adjusting them to my needs. I used the Polyline tool for drawing lines and the Fillet tool for rounding the corners.

I decided to use 18 mm plywood. To increase the reliability of the structure, I used two layers of plywood in the leg area of the chair and three layers for the backrest. Before starting the work, I measured the thickness of the plywood, which varied from 17.3 mm to 17.9 mm. To simplify the calculations, I took the average value of 17.5 mm and proceeded with creating the sketch.

I decided to make a table without using glue, so the joints had to fit together with the smallest allowable gap. To achieve this, I started cutting out the pieces with joints, adjusting their sizes as needed.

The first version did not fit into the hole, the second one fit with difficulty but eventually broke due to insufficient clearance and shoulder thickness. The third and fourth versions fit without issues, but the locking wedge had a 2 mm gap. I decided to shorten the length of the wedges because, in my opinion, they spoiled the appearance. In the end, I settled on the fifth version, as the sixth one also worked but required slightly more effort to assemble.

Considering all the previous tests, I decided to make the holes for connecting the backrest and seat 0.1 mm wider so that the parts would fit together easily.

To join the two layers of plywood, I added recesses across the entire surface with a depth of 8.75 mm, into which I later installed rectangular plywood inserts. Thanks to this, the two pieces were connected, forming a smooth side surface. In the image, the red fragments indicate the locations of the inserts, ensuring the strength and precision of the joint. The green part is intended for securing the backrest of the chair to the sides using a wedge.

This is roughly what the entire structure looks like when assembled, with all the elements properly connected and fastened, forming a stable and functional shape.

After assembling the chair in the program, I created the layout and placed all the parts on a sheet measuring 1220 x 1520 mm. For convenience, I separated all the parts for the grooves into a separate layer and saved the file in DXF format.