Compression Bits
“The bottom of the material is pulled upwards while the top of the material is pushed downwards thus eliminating the risk of damaging the laminating surfaces.”
What is a Compression Bit?
A Compression bit is the combination of both up-cut and down-cut spirals. Typically, a compression spiral has an up-cut single, double, or triple flute at the tip of the cutter, approximately one-third of the cutting length. The remaining two-thirds is ground to give a downcutting shear. By combining both geometries, you achieve a win/win situation. The bottom of the material is pulled upwards while the top of the material is pushed downwards thus eliminating the risk of damaging the laminating surfaces. When run at full depth, the bit leaves a sharp, clean edge on both sides of your workpiece.
Why use a compression bit instead of a conventional up-cut or down-cut?
Compression bits are used extensively for cutting double side laminates such as melamine or plywood. These tools can also be used on natural woods where edge finishing is a problem with standard spiral tools. A dedicated up or downwards spiral may only give a good finish on one side of the material if the material is laminated. Where both sides of the material require the best possible finish, a compression bit is your best solution.
How do I use a Compression Bit correctly?
While compression bits are the tool of choice for cutting double-sided laminates, it is essential you use the tool correctly. There are cutting edges on the bottom of most tools, therefore a direct plunge into the material will be fine. But let’s consider the spiral itself for a moment. The spiral of an up-cut tool will clear the waste material from the hole which will prevent heat build up and tool dulling.
The spiral of a down-cut or compression bit will force the waste material down into the hole, causing excessive heat and will soon damage the cutting edges. The solution is to ramp these cutters into the material away from the final edge that you will be cutting. A plunge is direct vertical movement into the material, a ramp is a plunge incorporating a forward movement. By ramping the trailing side of the tool is not enclosed and allows the waste material to come out behind the tool.
