Using a Circular Saw for ripping and cross cutting timber

How to cut straight with and without a guide rail

Using a circular saw is easier and you'll get a better finish if you follow these tips!

Versatile - probably the most used power tool of all especially for first fix carpentry, it is often referred to by many as a ‘Skilsaw’. That’s because Skil is actually the original brand that first marketed and sold portable hand held circular saws, so calling yours a Skilsaw is a bit like calling your Dyson a hoover.. it is just a brand name that has stuck (unless yours is actually made by Skil of course..).

You are about to learn how to use one of the most versatile and useful carpentry power tools you can buy. Amazingly you can use the same handheld power saw to manufacture and install delicate cabinetry work as you can to cut every roof component for a house all the way from the ridge to the fascias!

Value - what’s more circular saws are relatively inexpensive to buy too, a decent all round saw that would be good for most tasks can set you back as little as £120.

Circular saws are available in many different sizes (blades & motors) and come with with mains or battery power. Mains powered will always be more powerful than battery but they have come along way lately and some battery powered circular saws are amazing.

Does Size Matter?

You will either be looking at a 7" or 9" saw, that is 184mm or 230mm diameter of blade. Generally a 7" saw is enough for most jobs as it can cut to 65mm deep and it is light and easy to handle. A 9" saw will cut to 84mm deep but is quite large and heavy unless you are cutting roof rafters, joists/beams and other large framing timbers.

Choosing the correct circular saw blade with the right amount of teeth is essential to get a quick and good quality finish. As a general rule the more teeth there are the finer the cut. For rough first fix carpentry, you may find a blade with 24 teeth is enough. For fine finish carpentry at least 48 teeth. Although generally supplied with a HSS blade, it is worth investing in a good quality TCT blade if you can which are far more durable. These blades can also be sharpened which means unless you damage any teeth a good blade can last you a long time.

Get to know your tool (that is not a euphemism..)

The picture below labels the various components of a circular saw followed by a description of their use and some general pointers;

  • Power cord – Always ensure the saw is unplugged from the power source or battery removed before adjusting anything like the blades depth etc. Otherwise you are going to have a tough time picking your nose without any fingers. Additionally always ensure the cord is well away from anything you are cutting and isn't going to trip you over whilst you move around.
  • Goggles – I don’t mean to bang on about safety but splinters will fly towards your face when using a circular saw and whilst you can perform the safety squint which most tradesmen have mastered your eyes will have a far better chance of survival if you wear some safety goggles. You can get some sexy <a href="http://tidd.ly/c9351281" rel="nofollow" target="_new">Dewalt Safety Glasses for £3</a> if you are image conscious or there are ladies around.
  • Riving knife – this piece behind the blade keeps the two pieces of material that has been cut separated and stops it from pinching the back of the saw blade as it spins. Without it the circular saw would need to work harder and you can burn out the motor. It can also help prevent the saw kicking/flying backwards too if you are not using it safely. Some tradesmen will remove this as it stops them dropping the saw into the middle of sheet material however it is there for safety and best left in place.  
  • Base or bed - this is the flat base of the saw that will hold everything together and slide along the work piece. At the front it has two slots that you can use to guide the saw. Generally the one on the right is for performing straight cuts and the one on the left is for when the saw has been fully tilted over for bevelled cuts.
  • Depth adjuster – turn this knob to loosen the clamp on the vertical rail so you can raise or lower the blade into the base plate therefore adjusting the depth of cut. The blade should have three teeth protruding like the picture below when set to the correct depth. This is for efficiency and again for safety too, because it is much harder to cut your fingers off when only the tips of three teeth are protruding below the material. There is no need for three inches of blade to be protruding through the underside of the material - that is just dangerous and asking for trouble.
  • Safety button & trigger – in order to start the saw you will need to push the safety button in as well as pulling the trigger. Always start the saw away from the material you are cutting and let it get up to full speed before cutting, never start a circular saw when the blade is touching the timber.
  • Upper guard – the upper guard contains/covers the top of the blade and doesn’t move. It also has an arrow on it that shows the direction the blade spins which also happens to be the direction to turn the bolt to undo the blade when changing it.
  • Lower guard – for safety the lower guard is spring loaded and covers the section of the blade protruding from the saws base. As you slide the saw into the material being cut, this lower guard slides back out of the way into the upper guard and then springs back to cover the blade again as soon as removed from the work piece. There is a lever attached with most good saws so the guard can be retracted manually too. Always ensure that this guard is operating smoothly and importantly your blade has stopped spinning and the guard has sprung back into position before putting the tool down. If not the saw will take off down the road.
  • Front handle – for extra stability and control a handle for your left hand is at the front of the saw (most saws are right handed)
  • Bevel adjustment– many have a tilt adjustment so that you can use a circular saw for bevelled (angled) cuts too which is handy. When the saw is tilted to cut on an angle the depth of cut reduces a lot.
  • Body – the housing that contains the saws motor
  • Guide clamp – your saw will likely be supplied with a guide rail to use when ripping timber down. Once slid into the saws base it is held firmly in place and adjusted with this thumb knob
  • Dust spout – A good quality circular saw will have the means to connect a dust extractor to it to safely remove dust, keeping the mess down and your lungs from clogging

Tips for using a circular saw:

  • Secure the work piece - make sure the work piece is supported all around and won’t drop once the cut has been made. If that happens, apart from the danger involved you may pinch the saw blade causing the tool to kick back
  • Set the correct blade depth – three teeth to protrude below the work piece
  • Using a circular saw jig, square or straight edge – when you use a circular saw for the first time or before you are too experienced as it will be difficult for you to cut straight until you are used to using the circular saw. To help, depending on the type of cut you are making you can use something to guide the tool perfectly straight and square


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