Feed and speed equation

[Bush Flyer]

Hi Ger21,
I started with a new carbide 4mm bit this morning and started cutting two 600mm lines with a 4mm depth cut the bit did not discolour but was still hot, so after playing with the feed rate and spindle speed, going by noise the best rate has turned out to be 5500mm/min with a spindle speed of 12000, it cuts with very little noise this is a lot faster that I have worked out with the equations but when I cut at 4800feed and 20000 spindle speed the wood starts to blacken after about 900mm cut.
I will speed it up again later but for now I will cut at a feed of 5500mm spindle speed 12000 RPM but I will have to learn a lot more about chip load.