Materials, Joints, and Construction (Seat it)

The main construction material used in the seat it project will be plywood. Specifically we'll use Russian birch plywood. "Plywood is made of three or more thin layers of wood bonded together with an adhesive. Each layer of wood, or ply, is usually oriented with its grain running at right angles to the adjacent layer in order to reduce the shrinkage and improve the strength of the finished piece. Most plywood is pressed into large, flat sheets used in building construction." While unattached, the ply can be molded around curves and then glued in place. This can allow for dramatic curved shapes for furniture and many other applications. - from madehow.com -- How Products are Made


Here is a side view of plywood. Notice that different colored stripes. They come from the different directions of the wood grain.

The thin sheets making up plywood are called veneers. These are not made from giant trees. Instead they are made from normal sized logs and cut out in a spiral fashion. The picture here shows how the the veneers are cut from a spinning log. These sheets would be thin and bendy on their own.

Here is a video that shows how traditional plywood is made. Our Russian birch plywood is made in a similar manner.

This is an image of a type of housing joint. This is similar to what you made in your phone holder. You will cut part of your housing joint with a hand saw (tenon or gents), and then use a chisel and mallet to clean out the remaining wood.

Here's an image of a cross-lap joint. This is often stronger than a housing joint, and may not need any screws for reinforcement if the cross-lap is deep enough and close-fitting.

PVA glue is basically the same as what is used in elementary school for gluing crafts together. It stands for Polyvinyl Acetate. It is has very little odor or fumes, is non-toxic (as long as you don't eat it), and is water soluble. It works great for holding wood together as long as you give it enough time to dry. If excess gets onto your project, it can be quickly wiped off with a wet cloth before it dries.

The countersink hole has a funnel shape and allows some screws to fit flush with the wood surface.


A clearance hole is wider in diameter than the threads of the screw. This is allows the screw to drop into a clearance hole and spin freely.


A pilot hole is smaller in diameter than the screw threads. This allows the screw to bite into the pilot hole and pull wood together.

Latex Paint can be used in your project. It can thinned and cleaned using water. Oil -based paints must be thinned and with "thinner" (mineral spirits). We will use latex paint if painting.

Here's how acrylic plastic sheets (pmma) are made.