Bits, feeds and speeds; Everything for your Ratrig Killerbee

Before setting up any file for cutting, certain parameters must be considered in order to achieve the desired finish and accuracy. Chief among these is Chipload per Tooth (CPT), which is the size or thickness of the chip removed by each flute per revolution. To determine the optimal CPT, a variety of factors must be taken into account, including the power and rigidity of the machine, the hold-down of the part being machined, spindle horsepower, cut depth and width, tool sharpness, cutter type, and the material being cut.

The feed rate and RPM, (Feed and Speed) should be set in the CAM software used to create the toolpath to cut. On this page you find tools to aid in choosing the appropriate settings for a given material/router bit combination, but these may need to be adjusted through a process of trial and error.

Most controllers can be used to adjust both the feed and speed at while the program is running, and by listening to the sound the cutter makes, one can often optimize the given parameters. It is also important to note that chips should be created instead of dust, as this will help to remove heat from the cutting process, thus extending tool life and improving edge quality.

When determining the feed rate and machining direction for a project, it is usually suggested to start off with a feed rate that is approximately one-half the calculated amount and gradually increase it to the capacity of the machine and the finish desired.

Direction of cut for woods will usually be conventional milling or cutting forward, and the depth of cut should not be greater than twice the radius of the bit. For Aluminium, the depth should be less or equal to the radius of the cutter and climb milling could be used to achieve a good finish.