Flush trim router bits are available in various types, each designed for specific woodworking tasks. Below, I'll describe several common types of flush trim router bits:
1. Straight Flush Trim Bits: These are the most basic and widely used flush trim router bits. They feature a straight cutting edge and a bearing that runs flush with the cutting edge. Straight flush trim bits are excellent for trimming the edges of laminates, veneers, or any material that needs to be flush with an adjacent surface.
2. Pattern Flush Trim Bits: Pattern flush trim bits are similar to straight flush trim bits but feature a top-mounted bearing. The bearing is slightly larger in diameter than the cutting edge, allowing the bit to follow a template or pattern placed on top of the workpiece. This type of flush trim bit is commonly used when multiple identical shapes need to be routed, such as when creating multiples of a curved or irregular shape.
3. Shear Flush Trim Bits: Shear flush trim bits have a cutting edge that is angled or sheared rather than straight. This angled design reduces the chances of tear-out or splintering while providing a smoother cut. Shear flush trim bits are ideal for trimming delicate materials, such as plywood, where a clean and tear-free cut is desired.
4. Spiral Flush Trim Bits : Spiral flush trim bits feature a spiral or helical cutting edge, similar to spiral router bits. The spiral design allows for more efficient chip removal and reduced heat buildup during operation. Spiral flush trim bits are generally used for trimming or shaping edges and can provide a cleaner cut compared to straight-cut flush trim bits.
5. Compression Flush Trim Bits: Compression flush trim bits are designed with a combination of up-cut and down-cut flutes, allowing for both upward and downward chip ejection. This configuration helps prevent tear-out on both the top and bottom surfaces of the workpiece. Compression flush trim bits are commonly used for trimming laminates or veneers to achieve clean and smooth edges.
6. Mortising Flush Trim Bits: Mortising flush trim bits are specifically designed for creating mortises or square holes. They usually have a squared-off cutting edge, allowing for precise and clean corners when routing mortises. Mortising flush trim bits are commonly used in joinery work, such as creating mortise and tenon joints.
7. Bearing-Guided Rabbeting Bits: Although not strictly flush trim bits, bearing-guided rabbeting bits can also be used for flush trimming. These bits have a bearing mounted above the cutting edge and are primarily designed for creating rabbets or rebates. However, by adjusting the cutting depth, they can be used to trim and flush the edges of a workpiece.
These are just a few examples of the different types of flush trim router bits available. It's important to choose the right type of bit based on your specific woodworking needs and the desired outcome. Always remember to follow safety guidelines when using any router bit, including wearing appropriate safety gear and ensuring the workpiece is securely held in place.