CNC newbie looking to build a machine

Hello,

So the title says it. My background is that I'm an industrial automation mechanic with a hobby machine shop in my garage. Have an old Bridgeport and a decent-ish 9x20 lathe with upgrades. I've been thinking about building a CNC machine for a while, but got caught up in other projects like designing and building a miniGP race bike.

Anyway, I started with an X2 mini mill from Harbor Freight, which I still have. I've been thinking about using the head/spindle from that. I'd like to be able to cut aluminum and steel with it. Aside from trying to recreate a Bridgeport and or mini-mill design, my research includes watching ThisOldTony on youtube build his fixed gantry style router. I've been thinking of going this route, as it seems like it would be pretty easy to get the rigidity needed. Maybe upsize the bearings from what he used, and increase the rigidity of the gantry. Admittedly, at this point, I don't yet know what I don't know, design wise anyway.

On the plus side, I already have machine tools to use to build this. At work, I will very soon have access to a 24"x60" surface grinder, so making very flat and precise mounts for linear rails will be easy. I see this machine as mostly working with aluminum, some steel, but I'd rather it be more robust so I can be the limiting factor in what it does, rather than it's own weaknesses. If I do it with the X2 spindle, I'd likely assume I'll use a 3/4" collet and setup an air cylinder and potentially make a tool changer after making enough end mill holders with a 3/4" shank. I would consider using BT30 if I could find a spindle for that easy enough.

Assuming this machine will be built, if it works as well as I'd hope, I'd start looking into what it would take to build a lathe spindle with an encoder so use as a 4th axis so I could potentially make things like shaft splines and such.

I look forward to learning more about this, but if you have any critiques or design considerations, go ahead and chime in.

It sounds like what you really want is a Vertical Machining Center. Most of us here are building routers for cutting wood and similar materials,but they won't cut steel very effectively, if at all. While it seems like you're well set up for building a router, and probably could build one that would do an acceptable job with aluminum, if you're really shooting for steel, you need a much heavier and stiffer machine than you're going to be able to build yourself, unless you've also got an iron foundry in your garage. Your best bet would be to keep an eye out for a used VMC with a broken or obsolete controller. Often machine shops will sell them for scrap value, just to get the space back that they were occupying.

You can buy BT30 ATC spindles fairly cheap from China (AliExpress). I haven't bought one (yet) so can't recommend a specific model.

Don't limit yourself by using the X2 spindle.

I guess especially if I sell the X2 as complete, it might pay for the BT30 ATC spindle.