PORTABLE LUMBER MILLS
he desire to gain a deeper understanding of wood eventually leads some woodworkers out of the shop and lumberyard, into the woods, and back to the tree itself. By sawing your own lumber from logs, you can produce boards that exactly meet a project’s specifications and gain valuable insight into wood as a living material. Each step yields a thrill of discovery as you watch patterns of grain and figure emerge from the log.
A number of lumber mills on the market allow you to cut through-and- through cut, plain-sawn or quartersawn boards. These tools include large stationary production mills capable of cutting logs more than 20 feet in length, portable models with tough band saw blades, and still smaller units that use chain saws.
The procedures that follow show you how to cut logs into lumber with a chain saw that is guided by a jig that attaches to it. Besides the cutting jig and a heavy - duty saw, this simple method requires nothing more than a straight board, a hammer and a few nails.
Most chain saws are designed to crosscut trees—that is, buck the logs into shorter lengths after the trees are felled and delimbed. Cutting logs into lumber is a ripping operation in which the sawing is done along the length of the log. Ripping with a chain saw requires at least three times as much power as crosscutting, and the saw must run at full throttle throughout most of the cut. Because much portable lumber milling involves hardwood logs, it is best to use a direct - drive chain saw rated at a speed of at least 3000 feet per minute, with a rip
ping chain installed. To minimize strain on the saw, try to select logs that are relatively free of defects such as twist and taper, with few knots and burls.
Felling trees and cutting logs with a chain saw is dangerous work requiring safe working habits. Pay attention to your task at all times and keep cutting edges sharp, clean and well maintained.
Since prolonged work with chain saws can damage the ears, wear hearing protection, such as earplugs or ear muffs. Proper dress for chain saw work also includes a full-face shield and steel-toed boots; do not wear loose clothing. You can also don special chain saw gloves to protect your hands and a pair of safety chaps made from a tough, synthetic fiber, such as Kevlar™, to protect your legs should the saw accidentally slip or jump back.
CUTTING A LOG INTO BOARDS
1 Squaring the log
To mark out the cant—the squared - off part of the log—and maximize the number of boards the log will yield, scribe-a square on both ends of the log. Start at the end with the smallest diameter. Place the inside angle of a carpenter’s square just inside the bark, and mark two outside edges of the square with a pencil. Using the scribed lines as a guide, complete the square (left). Measure the sides of the square and transfer them to the other end of the log, making sure that the pith is centered in the square.
3 Cutting the cant
Set the log on spacers, with one side of the marked square vertical. Cut a 2- by-4 guide longer than the log, then position it on top of the log so that it extends beyond each end. Align the outside edge of the guide with the side of the square and nail it in place. Use wood shims to level the guide. Place the lumber-cutting jig on the guide (above) and adjust its fence so that it runs smoothly along the guide. Attach the chain saw to the jig following the manufacturer’s instructions.
To make the cut, position the jig on the guide at the smallest end of the log. Then, with the saw blade clear of the log, start up the saw and tip it forward so that the blade bites into the log. Carefully step backwards and draw the jig along the guide, cutting through the log to the other end. To cut the other sides, remove the guide and rotate the log. Repeat the procedure to align the guide with the square and make the cut (right). Continue until all the sides are cut. To cut the resulting cant into boards, use the chain saw and the jig to cut along the lines you marked in step 2. If you have a band saw, you can cut the log into a manageable 6- by-6 cant with the chain saw, then use the band saw to cut the cant into boards. With its narrower kerf, a band saw blade produces less waste than a chain saw blade.
------- BUILD IT YOURSELF
Simplify the task of squaring the ends of a log before cutting it into lumber with the crosscutting jig shown at right. The jig, which can be built to fit a variety of log sizes, consists of a guide and an inverted L-shaped frame with two triangular support brackets.
To make the jig, cut two pieces of Winch plywood for the frame. The lengths of the pieces should exceed the diameter of the largest log you expect to handle. The width of the top piece should equal the desired width of cut. Screw the two pieces together along with the triangular brackets. Screw a 2-by-4 guide that is at least 8 inches longer than the diameter of the log to the top piece, aligning its edge with that of the top piece.
To use the jig, set the log on spacers and position the jig atop the log. Nail the side piece of the frame to the end of the log, making sure that the guide is level and square to the log’s axis. Set up the chain saw and the lumber-cutting jig on the guide as you would to cut a log into a cant (page 38). Then start the saw and tip it forward so that the blade bites into the log (right, below). Draw the jig along the guide until you cut through the log. At the end of the cut, the crosscutting jig and the cutoff piece will topple toward you. Keep the blade from binding in the kerf and stand clear of the jig at the end of the cut.