Choosing the correct router bit is a process.  There are many router bits designed for specific materials.  Proper tool selection is imperative. We will go over materials below so you can better understand which router bits pair best with certain woods, plastics, foams, aluminums, etc.

1. The first thing to consider when choosing a CNC router bit is the material you are cutting. What material, or materials, do you plan on using for your project?  Each material requires a router bit with specific geometry so that it provides the best cut quality and performance.
2. The second thing to consider is the size of your router bit.  Typically, you want to try and use the largest tool possible because the larger the tool, the greater the rigidity of the tool, thus resulting in higher cut speeds.  You also don’t want to use a tool that has too long of a length of cut.  For example, if you want to cut ¼” thick material its best to use a cutter with 3/8” length of cut versus a 1” length of cut.  The longer the tool, the weaker the tool.  This will limit your speed and cut quality.
3. The third thing to consider is the size of the part you plan on machining.

The larger the part the faster you can route, because the vacuum hold-down will better secure the raw material to the vacuum bed surface.  For example: If you are routing a 2ft x 2ft board, you can use a large tool and route very fast because your vacuum hold-down on the machine will be able to secure this workpiece very effectively.  With that being said, if you are routing a 4in x 4in piece, this is much harder to hold down because you have minimal surface area under the part to secure it to the vacuum table. For this scenario, you may want to use a smaller cutter because the cutting forces will be less, therefore applying less force to the workpiece.