Plywood and 2×4s are the skin and bones of most modern structures. Both are inexpensive, easy-to-find, and endlessly adaptable. But just because they’re commonplace doesn’t mean they’re simple. Here’s a quick overview of what makes these materials such an essential for Makers, along with a few tips and tricks for your next project.
A type of “dimensional lumber,” 2×4s, as they’re commonly known, actually measure 1½”×3½”. 2×4s are invaluable in residential and commercial construction, but their strength and low cost make them a great option for many projects.
When shopping for 2×4s you’ll want to take your time selecting each piece to find the straightest boards possible. Sight down the length and look for any twisting or bowing. Because they are made in such vast quantities, you’ll find 2×4s for sale that are anything but straight.
Oriented on-edge a 2×4 has a considerably greater ability to resist bowing then on its face. However, the real strength of the 2×4 is achieved when it’s used as part of a system. Used in wall framing the 2×4 “studs” are placed vertically every 16″ inches and connected to horizontal 2×4s that are called plates. Done properly, a 2×4 studded wall can hold a whopping 1,100lbs of load per linear foot!
Most 2×4 stock in the United States is yellow pine. While it’s considered a soft wood, yellow pine is very strong and easy to cut and shape. Unfortunately, this wood can contain pitch or sap, which will gum up your saw blades and can even make them unsafe to use. Clean your blades with a pitch and resin remover or a biodegradable product like Simple Green. Once they’re clean give them a good rinse with water and dry them thoroughly.
Adapting 2×4 for Furniture
One of the best-kept secrets of the 2×4 is its ability to be used in furniture making. Lurking inside that unassuming lumber is perfect woodworking stock just waiting to be released.
1. Flatten one face on a jointer or with a hand plane.
2. With the flat face down, run it through a thickness planner until it reaches your desired thickness. This will ensure that both faces are parallel to each other.
3. Give it a trip through your table saw to square off one edge.
4. With one edge perfectly straight, flip it over and cut the stock to the desired width. The result will be material that’s straight, square, easy to mill, and very inexpensive. Use it to make templates, as set up stock for cuts, or as the finish material itself.
This layered, engineered wood has applications from woodworking to aircraft construction, and everything in between. Also known as sheet stock, plywood is made by peeling a log on a large lathe, creating a long continuous sheet that is then cut and stacked into layers known as plies. A sheet of plywood must contain an odd number of layers, with a minimum of three core layers along with the outer or “face” layers.
In lower-grade products, the grain of each layer is rotated 90° to the previous layer and will contain voids within the core plies. Higher plywood grades will be rotated 45° per layer and have little or no voids at all.
Marine-grade plywood resists delamination and fungal attacks. Aircraft-grade plywood is stronger, lighter, and more flexible. Pressure-treated stock is meant to be used in outdoor applications like sheeting or decking.
A critical benefit to having the grains of each ply run in different directions is that they counteract wood’s natural tendency to expand and contract across the grain. This provides structural stability, ensuring that the sheet stays the size that it was intended.
Plywood is available in a wide variety of “face” plies. Softwood faced plies, such as pine, are the most common, but you can also find plywood faced with hardwoods or even oily exotic woods intended for furniture.
Roll Your Own Bendy Board
One of the more unusual types of plywood is “wiggle” or “bendy” board. These products are designed to be flexible and allow for heightened creativity, but they can be expensive. Here’s a trick for making your own flexible plywood using a process called kerfing.
1. Select a product that’s at least ⅜” thick and preferably with thin plies.
2. Cut out the piece that’s meant to be bent, making sure the “face” grain is running with the length of the piece.
3. Make shallow crosscuts on the backside of the piece in the area that’s going to have the radius. These cuts should be about ⅛” apart with the blade stopping short of cutting into the last layer of core ply. With so many different types of plywood out there, the depth and spacing of each cut will vary. You’ll need to experiment.
4. Give the remaining uncut plies a thorough soaking. This will soften the fibers of the wood and allow them to bend to your will.