Using feed rate calculators does not really work for a hobby CNC like the X-Carve. The programs assume no flex in the machine. So we hobby folks need to do some experiments to find the best bit and parameters.
I spend some time doing experiments to find the best bit and cutting parameters for a series of materials using the X-Carve.
In the table you can see what I found as the best parameters and bit:
Feed Rate - FR in (mm/min)
Plunge Rate - PR in (mm/min)
Depth Increment - DI in (mm)
Bits tested: Two flute straight and one flute up-cut
6.5mm MDF: FR 1950, PR 375, DI 3, bit Two flute straight
4mm Ply wood: FR 2600, PR 500, DI 3, bit Two flute straight
2.8mm Polycarbonate: FR 800, PR 250, DI 0.5, bit One flute up-cut
3mm HDPE: FR 1300, PR 250, DI 3, bit One flute up-cut
8.8mm Glass fiber reinforced plastic: FR 800, PR 150, DI 2, bit One flute up-cut
2.2mm Carbon fiber : FR 800, PR 150, DI 0.5, bit One flute up-cut
Some video I took during the experiment