Homemade desktop CNC - cutting 0.8mm mild steel out the question?

[irving2008]

nothings impossible with the right cutter, power and rigidity... you'll need to use a small, e.g. 3mm, cutter to bring the revs required into a possible range...

rough calcs...
cutting speed Vc for steel = 30m/min, so for a 3mm cutter revs required at spindle, N = 1000 * Vc/(pi * d) = 1000 * 30/(3.14 * 3) = 3000rpm
Assume feed per tooth Vz = 0.1mm/rev so feed rate Vf = Vz * flutes * N = .1 * 2 * 3000 = 600mm/min
Removal rate Q = width of cut * depth of cut * Vf/1000 = 3 * .8 * 600/1000 cc/min = 1.44cc/min
Power P = KQ where K = 70W/cc/min for steel so power = 70 * 1.44 = 100W (at output = 200W input)
Torque T = P * 60/(2pi N) = 100 * 60/(6.28 * 3000) = 0.3Nm

So relatively little turning force required at 3000rpm on spindle and a typical router should be up to the job and feed rates are not so high... use plenty of cutting fluid and dont go too deep into the sacrificial and it should be possible... but you'll need a decent carbide endmill with no more than 2 flutes. Dont go too low on feed rate or you'll end up rubbing and burning out the cutter.... if you can go a little faster than 600mm/min and you have the spindle power at those revs then worth trying a tad faster.