By Dean Bielanowski
You have purchased a hand held circular saw for cutting up wood or composite materials but which is the best blade to buy? Unfortunately there is not one simple answer, as blades are designed primarily to suit a particular cut, or particular material.
When dealing with natural lumber there are basically two types of cuts. These are “rip” cuts and “cross” cuts. Rip cuts are cuts made along the grain of the wood. Cross cuts are cuts made perpendicular to the grain direction of the wood. There are circular saw blades better suited to making these two types of cuts.
For rip cuts. You generally want to have a blade with less than 24 teeth, preferably around 12 – 16 teeth is better. Rip cutting is somewhat “easier” on the saw than cross cutting because the saw is following the grain lines. Think of peeling the outer skin off a carrot. It is easier to peel from bottom to top than it is to peel around its circumference. Rip cutting also tends to produce larger slithers or cut wood and large debris, hence having less teeth on the blade means more space in between those teeth to clear wood slithers and debris from the kerf and around the blade. Less debris causes less friction while cutting so you usually get a cleaner cut with a low-tooth-count ripping blade than with a high-tooth-count cross cutting blade. Less friction also means less heat build-up and this results in maintaining tooth sharpness for longer.
When cross cutting the blade is slicing across virtually every fiber in the wood, and hence it requires more effort on the saw, and more teeth on the blade to produce a cleaner cut edge and face. Because the debris is much smaller when cross cutting and cutting across fibers tends to produce more grain tearout, more teeth on a blade results in more teeth being engaged in the cut at any one point in time. So a minimum of a 24 tooth blade is needed for cross cutting, but if you require a better cut edge quality, then add a blade with 40 or more teeth. Because handheld circular saws generally use smaller diameter blades than table saws or chop saws, 40 tooth blades may be the highest tooth-count blade you might get for your saw. Table saw blades and chop saw blades may have as many as 100 or 120 teeth for ultra-fine finish cross cutting.
Think also about the quality of cut needed. If you are cutting pine framing, then edge quality may not be too critical, so you can get away with a lower tooth count blade. An 18-24 tooth blade is a reasonable blade to perform both cross cuts and rip cuts if cut quality is not important.
Also consider the material being cut. For natural wood the above rules will apply for tooth count, and any decent quality blade with an ATB (Alternate Tooth Bevel) profile will work well. For composite materials like chipboard, MDF or melamine you can buy blades with a TCG (Triple Chip Ground) profile that tends to give a cleaner face edge with less chipout. Such TCG blades can also be used for cutting thin aluminium and plywood, although a general combination blade of around 24 teeth will work well on plywoods.
The only other factors to take into consideration are, 1) making sure the blade arbor hole matches the arbor diameter on your saw, 2) Ensuring the blade itself is rated to spin higher than the maximum RPM your circular saw delivers, and 3) Making sure you secure the blade on the saw in the correct orientation!
