As any good woodworker knows, there are a lot of different cut and joint types out there. But among these several joint types, few cuts are more essential to successful woodworking than the dado cut.
On the surface, a dado may look simple enough. After all, it looks just like a squared-off trench cut perpendicularly through a work piece’s surface. But in truth, a successful dado cut cannot be made with any old woodworking tool.
Instead, you often need to call in the service of specialized woodworking equipment such as a dado blade.
If you’ve never used one before, that’s perfectly okay. This guide will teach you the basics of this useful tool. With all of that information in mind, you’ll be able to take the next step and learn how to use such a blade without further delay.
What Is a Dado Blade?
Before we go too far, though, let’s take a moment to understand dado blades at a basic level.
In essence, a “dado blade” is one or more circular blades used on a table saw for the purpose of cutting precise dado grooves.
Dado blades come in two different types, stacked and wobble. As you’ll see below, these blade types have their own benefits when it comes to cleanly cutting dados to meet your project’s specifications.
It’s worth noting that not all table saws are compatible with dado blades. This is a result of their construction as well as their primary method of operation. Under no circumstances should you ever use a dado blade or set on a table that is not certifiably compatible.
Doing so can be significantly dangerous. Instead, you may be able to achieve comparable dado grooves by utilizing a router and a dado bit.
The Two Types to Know
Now that you know what these blades are in general, let’s take a closer look at the two major types.
Stacked Dado Blade
This second title is more descriptive of this kind of dado blade because, in reality, these “blades” are actually a unified set of individual blades that work in tandem to create a clean dado cut. This makes them fairly different from almost all other table saw blades, which usually accomplish their cuts with just a single cutting edge.
One way to think about a stacked dado set is to envision a sandwich made out of individual cutting components.
Though different woodworkers may modify this standard formula, these sandwiches almost always start and end with a single cutting blade. Then, on top of that, a woodworker would add what is known as a chipper blade. These blades have 2 – 4 teeth that are used to clear debris out of a dado cut as it is being made.
In practice, a woodworker may choose to add more than one chipper blade to their dado set “sandwich.” As you might expect, each added chipper blade makes the overall set just a little wider.
When it comes time to cut, these wider sets are able to cut wider dados. So, in that sense, the width of a dado cut made using a table saw is often dependent on the number of chipper blades used in the saw’s dado set.
However, the addition or subtraction of chipper blades is not the only way to modify the width of your dado cuts when working with a dado set. In fact, you can also add so-called “spacers” that perform the same function without requiring the purchase of more expensive hardware.
These spacers are often made of reinforced plastic and come in varying widths. As such, they are the best option for creating the precise dado width that your project requires.
Wobble Dado Blade
Without a doubt, you’re more likely to see a dado blade set used in either a professional or hobbyist workshop. However, some craftsmen prefer to use the second type of dado blade, known as a “wobble blade” or a “wobble dado.”
This is a unique type of table saw blade that is made up of a single cutting edge mounted onto an adjustable center. This center allows the whole blade to “wobble” in a controlled manner while it rotates, which in turn can create a dado of just about any reasonable width.
That being said, it should be clear that these blades do not “wobble” in the manner you may be expecting. Instead, a wobble dado sways back and forth in an “S” pattern while it spins. This swaying motion is controlled by two outer plates, which can be adjusted to determine the eventual width of the dado cut.
In practice, these plates make it far easier to adjust the width of your dado on the fly, rather than needing to take an entire set of blades apart (as you would with a dado set).
However, as you may have already guessed, wobble dados are less favored among woodworkers. This is primarily because their operation is prone to introducing vibrations into a cut. This can lead to some imprecision, especially as the flexible center begins to age and degrade.
Also, wobble dados tend to require more practice to master properly (even though they almost always cost less at the hardware store).
What Sizes Do Dado Blades Come In?
Dado blade sizing can vary depending on the type of dado blade you’ve decided to use.
For most folks, that means opting for a dado blade set. So, when it comes time for sizing, you’ll want to start by checking out the available sizes for your set’s outer blades. These typically come in 8-inch to 10-inch sizes that are just large enough to make a groove without making an entire through-cut (they are not intended for that purpose, after all).
After selecting your outer blade sizes, you’ll next want to find chipper blades of comparable diameter. But more importantly, you’ll want to choose chipper blades that are of appropriate width to achieve your desired dado groove size.
This can be alone or in conjunction with spacers. To that end, chipper blades usually come in sizes such as 1/8-inch, 1/16-inch, and 3/32-inch. Meanwhile, spacers can come in those widths as well as some that even smaller.
Selecting a wobble dado blade size is a fair bit easier, given that you’re only working with one piece of hardware.
In most cases, these wobble blades come in the same sizes as the outer blades of a dado set. So, expect to see sizes from 8 inches to 10 inches on your local hardware store shelve.
You will need to pay close attention to the width range offered by each wobble blade, though. These can determine how large or small of a dado you can cut with that particular model.
What Are Dado Blades Used For?
As their name suggests, dado blades of all types are primarily used to make dado grooves in the perpendicular surface of wood workpieces.
However, with a little practice and finesse, these specialized table saw blades can also be used to make a variety of groove cuts. For example, a dado blade could be used to make precisely-sized rabbet cuts. In the same vein, these blades could also be used to make a set of lap joints.
Beyond these kinds of straight-sided joinery, however, a dado blade’s productivity may be more limited.
Since these blades cannot be set at an angle, they certainly cannot be used to make dovetail joinery. At the same time, all dado blades are sized exclusively for the purpose of cutting grooves. As such, they are not appropriate for making rip cuts or any type of through-cuts, for that matter.
How to Use Dado Blades Safely
It is well known that dado blades present some risk to the user, even when they are utilized in a properly compatible table saw. As such, it is important for you to keep a few key safety tips in mind before trying out a dado blade for the first time:
- Follow regular table saw safety tips: As always, follow all safety procedures appropriate to the use of a table saw. This includes wearing eye protection and only running the blade when you are ready to make a cut.
- Use push blocks: It is essential that you keep your hands and fingers far from your dado blade. One way to do this is to make push blocks that allow you to slide your workpiece in and out of place safely.
- Never work with damaged hardware: Dado blades (especially sets) can become dangerous if they suffer a sudden structural failure. As such, you should regularly inspect your blades to check for wear or damage. If you find any faults, the blade should be put out of use immediately.
By now, you should have a pretty good understanding of what a dado blade is and how it operates. Should you be considering buying one, have a look at my list of recommended dado blade sets.
In addition, you should understand the numerous ways you should (and should not) use these specialized table saw blades – especially when it comes to taking safety into account.
In the end, you may decide that a dado blade is more trouble than it is worth. But if you do end up using one, be sure to practice with it a bunch of scrap wood before utilizing it full time in your woodshop.