Photo: eyeem.com
If you want to cut grooves in wood for making joints such as tongue-and-groove, dado and rabbet, you need a dado blade. This is because it is designed to cut at different depths and widths.
The blade is ideal for cutting patterns in wood, but it comes in two different types that operate very differently. All this information is provided below so that you can make an informed decision when selecting one. Let’s get started!
In this post:
What is a Dado Blade?
A dado blade is primarily a set of blades that consists of circular saw blades and chipping blades. The blade is designed to have an extra dimension (width), which makes it possible to cut channels for joints or decorative purposes.
These grooves are required when making dividers, bookshelves, cabinets and many other pieces of furniture. You can use miter saws, router tables or clamp guides to carve out similar grooves, but these are a bit difficult to use.
Read More: The Best Dado Blade Set
How Do Dado Blades Work?
To understand how the blade works, you need to know how it is built. The unit comprises two outer carbide-tipped blades that are very similar to regular saw blades. These create the outline of the groove.
Between these two is a chipper blade and as the name suggests, it chips up pieces of wood to create a channel with a flat bottom. However, there is a different type that is called a wobble dado blade, which works in a slightly different way. The two types can be defined as follows:
Types of Dado Blades
1. Stacked
Stacked dado blades consist of two outer blades that are the regular circular saw blades, and between them is a set of chipper blades.
These chipper blades can range from 1 to 6. Their number can be increased and the more they are, the wider the width of the cut.
You can add spacers between the blades, which will allow you to customize the length of the width for fine-tuning and precision cutting.
That said, the two outer blades should have 18 – 40 carbide-tipped teeth each and the more they are, the better because it will result in a smoother groove edge.
On the other hand, the inner chipping blades have few teeth (usually 2 – 4) and this is because their main task is to chop out material. They are not built for smooth cutting.
Since the blades are stacked, the teeth of the inner blades should be offset so that they hit the wood surface at different times when spinning.
This type has the main advantage of delivering precise cuts and is commonly used by professionals. However, stacked dado blades are quite expensive.
Pros:
- Gives smooth, high precision cuts
Cons:
- Expensive
2. Wobble
A wobble dado blade is very different as compared to the stacked type because it is a single blade.
How does it create a dado cut? Well, this blade is positioned in such a way that it can wobble at a certain angle so that it cuts in a zigzag manner. When positioned at one spot, this zigzag movement creates some width, resulting in a dado cut.
To cut at different widths, the angle of the wobble blade can be adjusted, but this presents the greatest problem; inaccuracy.
By using a single adjustable blade, it is very difficult to create a flat-bottomed square groove. This wobbling also makes the unit very dangerous because the design causes vibrations that might loosen vital components.
On the bright side, this blade is very affordable and easy to use when doing width adjustment.
Pros:
- Affordable
- Easy width adjustment
Cons:
- Not very accurate
- Might cause dangerous vibrations
Buying Guide: We highly recommend the stacked type because it produces very precise cuts. In fact, most manufacturers do not produce wobble dado blades anymore because they are not highly sought after.
Common Joints with a Dado Blade
Photo: acmetools.com
With either one of these two types of blades, there are several types of joints that you can create. These are:
1. Dado
Dado joints are 3 sided channels that cut across the wood grain. They create strong, shear-resistant connections because they enable you to slot in fitting pieces of wood before nailing, screwing or gluing them together.
As such, these joints are commonly used when making bookcases, cabinets and the like, where the shelves must be firmly attached to the structure’s frame.
2. Rabbet
A rabbet joint is a cut made at the end of a workpiece. This adds some mechanical strength to the structure you are building because it prevents side to side movement and gives better resistance to downward pressure, just like with dado joints.
Aesthetically, rabbet joints also help to hide the appearance of multiple pieces in the intersection by creating the illusion of a single-piece design. This results in a more professional finish.
Because they are ideal for end pieces, the joints are mainly used when creating cabinet tops and the back edge of cases.
3. Finger
A finger joint consists of multiple channels on a single block of wood that actually look like fingers. Also called a comb joint, the rectangular cuts interlock to create a very strong intersection, which can be glued for additional strength.
You can use this joint for decorative purposes. However, it is most commonly used when joining long boards together such as floorboards, or when building a door.
4. Tenon and Mortise
A tenon and mortise joint resembles the plugging in of a USB device to a USB port. It consists of a square or rectangular plug (tenon), which is inserted into a corresponding square or rectangular hole (mortise) to create a perfect fit.
The two can be glued together for additional strength and are mostly used for frame reinforcement such as when making tables or chairs.
5. Tongue and Groove
Tongue and groove joints are edge-to-edge joints that provide a very sturdy fitting between similar objects such as wooden floorboards and panels. This helps to create a firm, continuous piece.
That said, the joint still allows the wood to expand and contract while maintaining the structural integrity of the flat plane.
6. Half-Lap
A half-lap joint can either be from channels at the edge or middle of a wooden block. The joint ensures that no extra thickness is added to the intersection and is commonly used when making picture frames and dust dividers in cabinets.
FAQs
1. Are Dado Blades Dangerous?
Just like circular saw blades, dado blades are very dangerous because the spinning cutting tips can cause very serious cuts. Always wear protective clothing such as gloves and goggles to prevent sawdust from getting into your eyes, and avoid any distractions.
2. Can I Use a Dado Blade on Any Table Saw?
No. Not all tables have a long arbor that can accommodate the width of a dado blade. Additionally, you need to ensure that the table saw insert has a wide groove that can fit the width of the blade.
Conclusion
In summary, dado blades are very handy woodworking tools because they help you to create neat, firm, professional-looking joints for different kinds of furniture and woodworking projects.