Feeds and Speeds
There are two main variables you need to be aware of when machining. The first is the rate at which the machine travels when cutting. This is known as 'feed rate' and is measured in mm/min. The second is the spindle speed (speed of the cutter) and is measured in RPM.
Both these variables are highly dependent on the type of cutter you are using, the material you are machining, the depth of cut you wish to make (this may change during the toolpath so think in terms of the deepest cut) and what feed rate your machine is actually capable of moving at.
Feed rates are typically entered during the CAM stage of the process (see SheetCAM Tutorial 1 and VCarve Pro 6.5 Tutorial 1)
There are many online guides as to the feed and spindle speeds and your cutter manufacturer may supply guidance about this. Due to the wide range of cutters and materials available there is an element of trial and error to determine which feeds and speeds are most suitable for your particular project.
Example feeds and speeds
Example feed and speed settings to get you started are:
Using our A3 Ballscrew CNC machine and a 90 degree V point cutter machining a 5mm groove in wood
Feed: between 1200mm/min and 2000mm/min Speed: between 20,000RPM and 29,000RPM
Using our 8' x 4' Rack and Pinion CNC machine and a 90 degree V point cutter machining a 5mm groove in wood
Feed: between 1200mm/min and 2000mm/min Speed: between 10,000RPM (167Hz) and 24,000RPM (400Hz)
When machining aluminium (using the largest tool possible for your particular operation!) the feed rate needs to be kept high to ensure large chips are removed (and the cutter does not melt your material) and a small amount of lubricant such as paraffin should be used. Spindle speed should be kept as low as possible.
This for guidance only. As stated above feeds and speeds depending heavily on various aspects specific to your project