Circular Saws
Bigger is Usually Better
Circular saws come in a few different sizes (based on the diameter of the saw blade), from 4" up to the most common size, 7-1/4".
They also are typically rated by horsepower and/or RPMs of the saw blade.
When choosing a circular saw, a good rule of thumb is to buy one that has
higher horsepower than other models of the same size.
While a 1-HP 7-1/4" circular saw would probably be adequate,
I like models that are at least two horsepower,
as they are less likely to bind when under a load.
Safety Features
Circular Saws all have some basic safety features.
Check to see that the saw you're considering has a safety switch,
which must be held before the trigger can be depressed.
There should also be a blade guard that moves easily when pushing the saw
through wood, but springs back into place when the saw is away from the stock.
As with all tools, circular saws can be very dangerous if not used properly.
Always read, understand and follow the safety instructions that come with the saw.
Additional Features
Better quality saws employ additional features such as an anti-locking clutch,
which are flanges on either side of the blade that will allow the blade to slip
if the blade binds on the stock,
to protect the motor and drive mechanism.
Another useful feature is a blade lock,
which locks the drive spindle in place, making it easier to change the saw blade.
A.C. Power vs. Battery-Powered Saws
A recent advancement in circular saws is battery operated, 4-inch blade models.
These are wonderful for small cutting operations,
such as paneling or 1/4-inch plywood.
They're lightweight and perfect when you need to reach high to make a cut.
However, they're lacking in horsepower, and aren't much use for cutting
more than a just a few 2x4s.
I would definitely recommend having one of these battery-operated units on hand,
but not until you have a number of other tools in your arsenal.