The theory is like so:
- for a given RPM, feedrate and number of flutes, you end up cutting chips of a given thickness. The math is chipload = feedrate / (RPM x nb of flutes). And chipload basically represents how aggressive you are in taking bites from the material. If you have a set of feeds and speeds that works for you, and you want to “just” move faster, then you can increase the feedrate AND increase the RPM in the same proportion, and you will end up with the same chipload, so the cut will pretty much be guaranteed to still go fine (actually, higher RPM will decrease cutting forces so if anything it should be an even easier cut)
- DOC is a different, unrelated parameter. The deeper you cut, the largest the forces on the endmill (because for a given chip thickness, the deeper you cut the longer the chip, and cutting “longer” chips takes more effort). If you double DOC, all other things being equal, you pretty much double the efforts on the endmill/machine. How deep a DOC you can achieve depends on the material, endmill diameter, machine rigidity, and stepper motor torque.
In your case, you initial post mentions using 10.000RPM, 50ipm and a 2 flute endmill. That’s a 0.0025" chipload. That works fine because you are taking such a shallow cut (0.003").
If you double the feedrate, and SINCE your RPM is already maxed out at the Nomad’s 10.000RPM limit and you won’t be able to increase it, you will effectively double the load. Would it still work ? Hard to tell without experimenting, the easiest would be for you to test incrementally higher feedrate values, using the feedrate override during a cut. If you push the feedrate and it stills sounds and looks fine, then you know. And it feels much more comfortable to start from a know good value, and dynamically bump the feedrate by e.g. 10%, see if it still works, rinse and repeat.
If you double the DOC, you will double the load. Again, would it work ? Maybe, maybe not, at some point the machine will give up (in the case of a Nomad, it’s likely to show up as the spindle stalling, or getting excessive chatter)
This is my super-long-winded way to say…just try incrementally higher feedrate and DOC values, and when you find the limits, dial that down by 10% and you will have found the maximum usable setting for that particular material and endmill combination. Sometimes it’s possible to theoretically predict the highest feedrate and deepest DOC that should be achievable, but vbits are just weird (e.g. their tip has a rotation speed of zero…) so experimentation is key.