The issue I'm having is that the values I get are either very high or contradict the rest of the internet. For cutting aluminium wikipedia recommends 75 m/min (246 SFM), which with an 8mm tool yields a spindle speed of 2980 RPM. That seems very low to me considering the spindle I'm looking at buying is 0 - 24,000 ! (Do the chinese spindles drop power at lower RPM?). Looking at the SECO tool brochure they suggest a cutting speed of 400 - 650 m/min (>1312 SFM) which is massively high and yields a spindle speed of 15920 RPM! Is this the difference having carbide tooling gives? How sensitive is cutting speed - is this something I should obey or a very loose suggestion?

Should I go for carbide with the higher surface speed to avoid low RPMs? Can the Chinese spindles handle low RPM or do they loose torque? Can hobby CNC machines handle the high feedrate? Can I follow the toolmakers recommendations on these types of machines?

To explain how I'm calculating each value, I start by finding spindle speed from the surface speed and tool diameter. Then I find feedrate from the spindle speed, chip load and no. flutes.

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When using the higher cutting speed I then end up with a high feedrate of 1336 mm/min. Can hobby CNC machines handle this kind of feedrate into aluminium? Can I reduce tool load by taking thinner cuts to obey the feed and speed requirements? How do you work out a suitable depth / width of cut? Ive been told that I want to make cuts with a width of about 1/4 of the width of the tool and depth of the width of the tool (so for an 8mm bit I'd cut 8mm down and 2mm wide.)

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Very new to hobby CNC so still getting sorted with the whole speeds and feeds thing! The trouble I'm having is finding consistent or reasonable numbers for things from the internet! I have a little experience with larger machining centres but I'm not sure what hobby machines can do!