Trade education and workforce development are two initiatives we value highly here at Dunn Lumber, so it should come as no surprise that we have close ties with Seattle Central College's Wood Technology Center (WTC). With roots dating back to the early 1900s, WTC's history intersects with ours at Dunn Lumber at various points (our very own Ed Dunn Jr. took some classes at Edison), and we're proud to be connected with such an exemplary educational institution.
Throughout the episodes in this series, we'll be speaking with Dave Borgatti, a long-time faculty member at the WTC, about the center's history, program offering, and various topics in woodworking education. Dave got his start in woodworking as a boat builder in Portland, Oregon, for Schooner Creek Boat Works, and ended up at WTC as an instructor in 1992. Since then, Dave has helped countless students—from boat builders to carpenters and cabinetmakers—learn the woodworking craft.
In today’s discussion, Dave and I cover the differences between the three types of circular saw blades and how to use each.
Watch our chat in the video above, or keep reading for a detailed recap.
Types of circular saw blades
There are three types of blades, and they correspond with the kind of cuts they make in a piece of wood.
- Rip blades cut with the grain.
- Crosscut blades cut across the grain.
- Combination blades can do both.
What is a rip blade?
A rip blade is an aggressive blade with deep gullets and large teeth with flat tops called “flat top grind.” It’s designed to cut through long lengths of wood along the grain. The blade has large but relatively few teeth, which creates less resistance and a rougher cut.
You’ll typically use a rip blade and then run the sawn edge of your lumber through a jointer to make it smoother. Alternatively, there is a newer style blade called a glue joint rip blade that also results in a smoother cut.
What is a crosscut blade?
A crosscut blade has much smaller teeth and shallower gullets than a rip blade and is used to cut across the grain. A crosscut blade's teeth have a bevel on the top which alternates side-to-side (kind of like little chisels); the term for this is ATB or “alternating top bevel.” This type of blade is commonly used for high-end plywood products and other kinds of veneered work where you don’t want tear-out, since it produces a very clean cut on both sides of the wood.
If you try using a crosscut blade to rip, it won’t work well. It will be very slow, and you’ll likely start to see smoke.
What is a combination blade?
If you’re going to be switching between ripping and crosscutting and don’t want to keep changing your blade, then you want a combination blade. A combination blade combines the two types of teeth you’ll find on rip and crosscut blades—it has a mix of deep and shallow gullets and more teeth than a rip blade. Sometimes, combination blades will also have a relatively new type of tooth shape with three facets called a “triple chip,” which works particularly well on plastics.
While combination blades are very effective and efficient, you still want to stick with a crosscut blade if you need to get a really clean cut.
What does saw “set” mean on a circular saw blade?
A saw blade's “set” refers to the distance the blade's teeth are bent away from the saw's blade. Bending the teeth alternately right and left gives the saw blade clearance, which prevents binding. Modern blades are not "set," but rather have thicker carbide teeth than the actual blade, which also prevents the saw from binding in the cut.
What are relief cuts in blades?
Relief cuts are small holes or cuts in the plate/center of the blade that help cool the blade and deaden sound. When you’re cutting a large piece of wood, the blade heats up; relief cuts allow the blade to expand as it heats up without warping.
What is the difference between regular and "thin" kerf blades?
A kerf is a slot left in a piece of wood by the saw as it’s cutting. The standard kerf is around ⅛”. Thin kerf blades are just over 1/16", and because less material is removed, the saw cuts easier and more efficiently. The downside to using a thin kerf blade is they cost more and can bend if the cut isn’t perfectly straight.
What to know about sharpening circular saw blades
Blades get smaller every time they’re sharpened. That’s why higher-quality blades have a lot of carbide on them—the more carbide, the more sharpening the blade can withstand. If you use a saw with a brake (i.e., SawStop or Bosch Reaxx), you will need to adjust the brake closer to the blade for the safety mechanism to work. Conversely, when you switch from an old blade to a new one, you need to adjust the brake away, or it will trip when you turn the saw back on.
Want to learn more about woodworking basics? Take a look at our other articles from the Wood Technology Series covering topics like the difference between planers and jointers or nominal and actual lumber sizing.