You can cut aluminum w/ NEMA17 motors as was done back in the Shapeoko 1 days, or see this Nomad project:
As @BartK noted, the biggest consideration for a desktop CNC machine is learning the machine’s limits and how to work within them — once you’ve fully grokked that you’ll be ready to consider upgrading. Upgrades arranged in bang-for-buck order:
- belts — the 6mm to 9mm upgrade was an obvious improvement, with no drawbacks. Better quality belts will help as well (if not running Gates branded belts, get them from SDP/SI or BB Man. or some similar reputable source). Different materials have different tradeoffs and work well for some folks
- aluminum wasteboard — big improvement in rigidity, no drawbacks aside from expense and the nerve-wracking worry over dinging it (I don’t use the one on my Nomad until I’ve tested out a file with the MDF in place)
- upgraded Z-axis — the improvement on Z-axis rigidity and accuracy/precision works well, but creates the possibility of a crash doing more than skipping steps on the motors or belts
Beyond those upgrades, the tradeoffs in cost/convenience begin to argue for replacing the machine — the X-Carve folks do this sort of thing a lot, and we used to do it on this side of the house back in the SO1/2 days (Brandon Fischer rebuild his SO1 from leftover parts after finishing his last upgrade), and my own SO1 had upgrades on all 3 axes (Y: shaft drive for double belts, X: double Makerslide, Z: Acme screw), but there’s a lot of work which can be done w/in the machine’s limits before starting on that road:
The big thing to remember is you’re not going to power through cuts on a machine with aluminum rails and plastic wheels — a more nuanced approach to feeds and speeds and toolpaths is required — if you don’t have CAM which does adaptive/trochoidal milling, that’s the biggest upgrade.