Hi Gary,

I take it you have filled in the setup page for your machine i.e. use generic gantry router and specify the weight of the gantry etc?

The two settings you don't understand are:

Cutting Width = Step over - what CAM strategy are you using to mill the cylinder? (I assume from a square block) If you are going for a slot cut then you should use 6mm and if using side milling of some sort then use 2.4mm on a 6mm cutter (although a 6040 machine may struggle with this much depending on depth of cut).

Feed Limit = the feed rate of your machine before stalling occurs or the feed rate limit you have setup in the machine control software (MACH3?) (The 2% is the % of the limit the suggested feed rate is running at e.g. GWizard may suggest 1000mm/min for a machine with a limit of 10,000mm/min, which would be 10%).

As Nick suggests I would try a single flute cutter for aluminium, unless you are going to side mill the block inwards to the cylinder using something like adaptive clearing or a similar strategy and then I would say your feeds for a 3 flute cutter are too low.