Group 33 - Skil Circular Saw
We are dissecting a Skil saw model 5400 circular saw. Its primary use it cutting relatively thin wood such as sheets of plywood or boards up to its maximum cut depth of 2-1/2 in. With a suitable blade it can also be used to cut other materials such as plastic, veneer, and metal. This model is primarily targeted at non-professional users.
The saw uses a small motor to convert electricity from a standard wall outlet into mechanical energy to drive a shaft on which the saw blade is mounted. It is not currently working; we think either the switch is broken or the carbon brushes in the motor are missing. Most of the visible outer parts of the saw are plastic, including the handles, housing, and the covering of the power cord. The guards are aluminum. The base plate and blade mount are steel. It also has a rubber stop that keeps the rotating guard from turning too far when it's released. Internally, the motor and power cord contain copper, and the motor uses carbon brushes.
This is not a very complex product; it uses a common mechanism (the electric motor) to perform a single task (running a saw blade). It doesn’t have a lot of settings or alternative functions. According to the manufacturer’s parts list, it has 57 components, which includes all of the fasteners and the individual parts of the motor. None of these components are complicated.
Under normal use, this product does not require regular maintenance; under unusually heavy use it might be necessary to replace the brushes in the motor occasionally. It is solidly constructed, and unlikely to need frequent repairs.
There are a large number of very similar hand-held saws on the market. This model runs from about $25 to $60, which is at the bottom end of the price range. It has a definite advantage in cost; some of the alternatives cost over $200. All of them have similar safety features. The engine used in this product has a good weight-to-power ratio, but is noisy and inefficient. The more expensive alternatives are frequently packaged with extra blades (this one is sold with a single blade suitable for wood), or have extra capabilities for cutting other materials. There are several cordless alternatives, which have the advantages that they can be used without easy access to an outlet, and the user can't trip over the cord, but they are also considerably more expensive, and are heavier due to the added weight of the battery.