The Gaff Rig recognizes that boat building involves inherently
dangerous activities, and each builder must be responsible for his own safety. The Gaff
Rig encourages all builders to read manufacturer’s instructions, follow all safety
precautions, and be pro-active in seeking out more information on reducing the risk of
injury or illness. Information presented here is general in nature and not intended to
replace the safety instructions provided with products or tools.
The circular saw usually makes everyone’s list of essential
tools for building one of our boats. The Weekender video and plans contain quite a few
tips for using the circular saw to rip long stock, cut curves and make plunge cuts.
Circular saws come in a variety of sizes now, with blades from
3" up to the de-facto standard of 7 ¼". While the smaller blades can’t cut
through material as thick as the larger ones, they do allow more sharply defined curves.
If you are only going to buy one circular saw, the 7 ¼" size is probably the most
adaptable to common tasks.
Whatever the blade size, a good blade is a must when starting on
a project such as ours. Thin kerf, carbide tipped blades can be found for under $20, and
make a world of difference when making curved and plunge cuts. You might be tempted to buy
a more expensive "plywood" or "veneer" blade, but a thin kerf,
"combination" blade is the most useful. You don’t have to change blades to
quickly saw 2 x material, and then change back when cutting the plywood.
Today’s circular saws have
safety features that make them safer than yesterday’s models. But safety is a
relative term, and taking just a few precautions can save you anguish even if you’re
using a 40 year old saw.
My father was severely injured when I was a child when a circular
saw became unplugged. Turning around, he set the saw on the plank facing the plug, walked
back and, laying his left arm on the plank as he bent down, plugged in the saw. The switch
had stuck in the "on" position, and like many in construction, my father had
wired the blade guard in the "up" position. The saw raced down the plank and cut
through his arm, scoring the bone, but not severing it. Twelve hours of surgery, and weeks
of physical therapy, returned the use of his hand. My neighbor, an experienced contractor,
also using a saw with its blade guard wired up, set the saw down on his thigh. He has no
idea why, but 72 stitches later, the guard is once again operative on his saws.
So leave the safety devices enabled. And then watch for
complacency during use. Think through each cut before you make it, keep the area clear so
you can make the cut from one end to the other without tripping over things. Watch the
cord to make sure it doesn’t hang up while you’re cutting (sometimes the plug
will catch on the edge of a long piece of plywood, and without thinking you start to try
and force the cut.) And let the saw cut the wood: if you have to force it,
something’s wrong, and you may be headed for injury. Stop, look around, and
don’t continue until you find the reason the saw is binding.
Beyond defeating safety devices and becoming complacent, one real
problem can arise on nearly every cut: kickback. Kickback happens when the spinning blade
is suddenly bound up or hits something very hard (like concrete under your plywood.)
Kickback happens to even the most experienced carpenters, so prepare for it. Position
yourself to one side of the saw, never with your face down near the handle and your body
lined up behind it. Keep your hands (both of them, whenever possible) on the saw even when
stopping a cut in the middle, until the blade stops.
Kickback due to binding can happen when the cutoff can’t
fall away from the kerf. If you are cutting stock in two, don’t make the mistake of
positioning a sawhorse on either side of the cut, which is the circular saw version of
cutting off the limb you are standing on. As the board tries to fall between the
sawhorses, the blade will be bound, and the saw will jerk, jump back at you, and remind
you of that scene in Silence of the Lambs.
I prefer to work with
the material as close to the ground as possible, using 1 x 2’s or 2 x 4’s to
support both sides of a long cut. This minimizes binding if I have miscalculated how the
kerf will open up, and errors are much easier to react to. If its plywood, and I know
I’ll be working my way across it on my knees, I make sure to support the plywood
where I’ll be kneeling with an additional 2 x 4. Blade depth should be set as shallow
as possible to cut through the material. And, even if your work area usually looks like
the den after the Superbowl, clear out an area so you don’t trip, get the cord hung
up, or cut something you intended to leave in one piece. Like the cat.
For long straight cuts in sheet material such as plywood, many
craftsmen use a straight edge clamped to the stock. First, they mark where the cut should
be, then measure the distance from the edge of the shoe to the blade on their saw, then
measure back from the original mark on the material that amount. Then they clamp the
straight edge to the stock with C-Clamps, double check that they have measured correctly,
and cut the stock by guiding the saw along the straight edge. Tool stores sell 8’
long straight edges specifically for this purpose, but any straight piece of lumber or
other material will do, such as extruded aluminum salvaged from sliding glass doors, etc.
An inexpensive jig can
be made that simplifies this. The picture shows one I cobbled together 5 years ago, fully
intending to make a more professional one later. But this one works fine, so I haven't
taken the time to make it pretty. I used a 2 x 6 with a good straight edge, and attached a
sheet of 1/8" doorskin plywood to it, making sure that the 2 x 6 was set back from
one edge far enough so that I could trim off a bit if I guided the saw along the 2 x 6.
Then, I did just that, cutting the doorskin on both sides of the 2 x 6. The jig is
finished. I mark the stock, position the edge of the doorskin at the mark and clamp the
jig down. Then I cut the stock by guiding the saw along the 2 x 6 edge. Fast, easy, and I
don’t have to remember which of those little marks on the tape measure are the
eighths to accurately position the jig.
Someday, I intend to use 3/8" or ½" exterior plywood
and make an 8’ straight edge jig that will be easier to store and use. A 4" wide
strip of plywood, with a 2" strip aligned with one edge and glued to the top would
work fine. When the glue is dry, guide the saw along the edge formed by the top strip,
cutting off the excess on the 4" wide strip, making a straight edge jig that would be
light and easy to clamp. A hole drilled in the end would allow it to be hung on a nail,
flat against the wall, out of the way.
Cross-cuts in material no wider than 18" are usually made
freehand, although I have seen miter and cross-cut jigs made much the same way as above,
but just 18" long.
Plunge cuts require a different technique. When cutting the front
hatch opening, a plunge cut is used, and unlike with other cuts, you have to hold the
blade guard in the up position while starting the cut. Here’s the correct procedure
to remain safe: adjust the blade so that it will barely cut through the 3/8" deck
plywood. Mark the cut lines clearly on the deck. Drive a large screw into the center of
the piece being cut out. Begin near one corner and place the front edge of the saw base
firmly on the wood, lift up the blade guard and line up the blade with the marked line.
Start the saw, and slowly lower it into the plywood. When the entire base is flat on the
wood, you have cut through. Move the saw slowly, following the marked line, to the corner.
Don’t move the saw backward with the blade spinning, as the rotation of the blade can
make the saw climb out of the kerf. Turn the saw around, and position it in the cut, turn
on the saw and move towards the next corner. Repeat for the other three marked lines.
Because the corners have not been cut through, the waste won’t twist and fall,
binding the blade. Use a hand saw or jig saw to cut the corners cleanly. Hold on to the
screw in the center to prevent the waste piece from twisting loose and tearing the corners
out.
The circular saw may be the most useful tool when constructing a
Pocket Yacht. As with any tool, knowing its limits and being aware of its safety features
is a must to spend more time sailing, and less time recuperating.
