In order to cut safely and cleanly, it is critical to calculate the correct feeds and speeds. The wrong settings can damage your workpiece, the machine, and endanger you and those around you. The settings for each job or toolpath depend on each of these four variables:
- Chipload: The measurement of the material removed by each cutting edge during a cut. Can be used to make adjustments to feed and speed parameters for cleaner, safer, and more efficient cutting.
- Drill (# of cutting edges): A rotary end cutting tool has one or more cutting lips and one or more flutes to pass chips and emit cutting fluid. Generally the number of flutes = the number of cutting edges.
- Feed rate (IPM/IPS): The speed of the tool (bit) traveling through the material. It is measured in either inches per second (IPS) or inches per minute (IPM).
Most calculations are in IPM, to get IPS - divide by 60. Start with a slow feed rate (around 2 inches per second) and increase as needed.
- Revolutions per second (RPS): The speed at which the spindle is rotating.
The ShopBot CNC Router calculates speed in rotations per minute (RPM) so convert accordingly.
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The Laguna CNC Router calculates speed in rotations per second (RPS) so convert accordingly.
¶ Utilize the recommended settings and the known variables to solve for the missing variable.
Chipload=RPS×CEFeedrate(IPM)
IPM/IPS=RPS×CE×Chipload
RPS=CE×ChiploadFeedrate(IPM)
CE = number of cutting edges