Well the mods didn't like the wording of my last post so it's now collecting dust in the engraving machines forum. Let me be clear that I am NOT asking for help with software or anything related to the original machine I started with. I've thrown out most of the original components of the machine already, just looking for guidance in figuring out how to make the machine capable of milling out softer metals like aluminum with reasonable precision.

I started out with an old New Hermes Vanguard V3400. Replaced the motion controller and PC with an Arduino + GRBL, and a Raspberry Pi + bCNC/f-Engrave. Now I've replaced the stepper motors with higher torque motors, and replaced the lead screws. It's made the machine quieter, and quicker, but my real goal is to make it capable of milling out pieces of aluminum, maybe other softer metals. I'd like it relatively precise, enough to make, say, brackets for my car. I'd also like to cut fine traces in PCBs for my own personal projects. I have questions on how to get my machine there, because I really don't have experience in CNC.

First, the axes I have are lead screws, and the nuts are entirely plastic. If I wanted to, say, mill out pieces of aluminum, would the lead screw bend or fail? Would it be relatively easy to upgrade to a ball screw?

Another thing. The original spindle motor is in the CNC housing, and a series of belts connect it to the spindle. The belt doesn't feel very tight and it runs at a fixed, high RPM, for engraving. The big question I have is, will I need to get rid of the belt drive and mount the spindle motor on the Z axis, or can I keep it the way it is?

Lastly, I was curious about GRBL. Is it powerful enough for a hobbyist like me? Or should I look into upgrading?

I do apologize if there's write-ups on all this that I'm not missing. I'm no CNC expert, in fact when I started this project I barely even knew what the acronym stood for. But any guidance would be greatly appreciated.