First you will need to select the correct size diameter blade. This can vary from 160mm for small cordless saws and up to 305mm for table saws. The most popular size for a portable circular saw is 184mm. Be sure to check your instruction manual, search the model number of your saw online or bring your tool in to store if you are unsure of which blade diameter best suits.
Depending on the outside blade diameter, the centre hole diameter will also change. This is called an arbor and is designed to fit flush to the machine. A circular saw blade pack usually comes with additional reduction rings, named bushes, to fit the blade if your machine has a smaller arbor size than the chosen blade.
The revolutions per minute or RPM of a blade is one of the most important considerations you should account for. This specification is most commonly seen when selecting a blade for cutting metal. Saws have different motors that spin at different speeds, so if your saw spins faster than what the blade's maximum RPM is rated, there could be issues.
There are many general purpose blades to choose from, but in some cases it's best to select a specialty blade. Specialty blades come in handy when cutting timber, aluminium, melamine/laminate or even metal and fibre-cement. These blades have teeth that are designed to handle the pressures of cutting individual materials.
Tip: Some saw blades require lubrication, particularly those involving steel, aluminium and other metals. Ensure you follow the correct recommendations for these. To lubricate aluminium blades, a wax like substance is rubbed onto the blade while it is stopped.
To get the right finish for your job, we also need to look at the number of teeth a blade has. Larger blades will have an increasing number of, but if you consider the options on a standard 184mm blade you may have teeth counts ranging from 24T – 60T. This is relevant when you are looking to produce clean cuts or rough cuts. Very simply, the more teeth the smoother the finish and the less teeth the rougher the finish. Blades may also describe this with keywords Framing/Ripping or Trim/Finish.
Tip: When cutting, set your cut depth to just penetrate the material thickness, this helps to produce a cleaner finish.
Now that you've chosen and installed your blade, make yourself aware of the following safe cutting practises:
Always check the blade is installed correctly before cutting.
Never push the saw hard, let the teeth and the machine do the work. Listen to the motor and feel for cues.
Never attempt to change direction, this may cause the saw to ‘kick back' and cause damage or injury.
Always ensure your material is held firmly, and you have space to comfortably perform the cut.
Dull or damaged blades are dangerous, so be sure to regularly inspect your blades for any defects such as tooth loss, warping or residue build up on the blade. Replace your blade if you see any signs of these defects. If your blade starts to struggle to cut cleanly and easily, it's time to replace or sharpen your blade.
If you're still unsure, visit your local store for more expert advice on how to select the right blade. Or, see our team in the cut shop to pre-cut timber to your needed lengths.
Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.
When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.