Archive for Digital Fabrication with furniture

Furniture Making with Digital Fabrication (2 of 4) Seat and Back

Posted in a.n.t., How-To / Tutorials with tags , , on January 11, 2011 by Ilan Dei Studio

The Seat and the back of the chair are grouped together in this blog post because they are both processed from the same material. Instead of using solid wood we are using a 1” thick Baltic Birch Plywood as the core material. This makes processing multiple chairs very simple using sheet stock on a 4’x8’ ShopBot.

The seat of the chair is set at 2” thick, both for appearance and for strength, so we need to laminate two sheets of 1” inch Baltic Birch Plywood together to make the 2” sheets.

Nesting 2D:

The Seat and the Back are the simplest to nest simply because they are cut directly from sheet stock and because they are both completely 2D cuts. To start with we extracted curves from the edges of the parts and from the areas that are accepting the legs and arms.  These curves are what we will use to create the toolpaths.

The seats of the chairs fit nicely together simply by rotating them and placing them next to each other. (Note: Do not “mirror” the seats because if you are going to accommodate arms you will need to make sure and mill the slots for the arms in the tops of the seats, if you mirror the parts you will then be milling these arm slots on the bottoms or the parts.) The backs do not fit together as perfectly as the seats but still nest well enough to get a good yield from a sheet. The back also cannot be “mirrored” and must be placed face down because you will need to cut a step into the inner circle to support the center decorative piece.

Now that both sheets are nested, the next step will be how we choose to hold down the parts while they are being cut. Both the seats and back are two small and awkwardly shaped to be held down by vacuum pressure alone and we do not want to screw down our parts because of the holes it would leave. Our solution is to use tabbing and to hold down the remaining parts with screws. Since the seats are so closely nested together we will need to add the tabs to the inner circles and screw down the circle pieces to the table.  (The inner circle cut outs are useful in creating a hold down system, but mostly they remove excess weight in the chair that would be a real inconvenience in the final product.) In the backs we can add tabs to the outer perimeter since we can screw down the excess pieces that are left around the parts. Continue reading

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