I am thinking of building a cnc router. I need it to cut the shape and holes in .063 to .090 aluminum sheets. My project will be a tube amp chassis. The largest folded chassis will be 20Lx8Wx3H with a .75 to 1 inch mounting flange folded to the inside on the 8 inch side. The unfolded sheet would be 28x14. Some times I will need to cut out the shape and cut the holes on a flat sheet and then have it folded. Some times I will need to cut the holes on the top, front, rear and bottom on a pre folded chassis. Can I extend the reach past the end of Y axis by 1 to 3 inches to machine the 20" face or will I need 8 inches of clearance on the Z axis or can I slot the base board large enough to insert the folded chassis from below? I will also be using it to drill garolite. These holes can be drilled rather than machined. I would also like to use this machine to cut box joints or dovetails on up to 3/4" plywood or pine. How much motor do I need? Should I use a router motor as a spindle? Is this a good use for a laser? If a laser is good, how much power will I need to cut both plywood and aluminum? See the attached pdf files for a sample of the chassis.
Any of the C-beam based Ox derivatives will do what you seek. You can either recess the end rail back several inches to where you can clamp the folded boxes to the end or you can frame an opening down the center that you can drop jigs into that will grip the box and hold the cutting surface at table level. The recessed end rail would probably be the simplest to use but will require a wider gantry system to get the full length of the box plus 1/2 spindle gantry width at each end. Above all, resist the temptation to build a tall up-and-over type system that tries to create a large volume by building a high gantry system. This just reduces the overall rigidity of the system and rigidity is your friend when it comes to cutting aluminum. Any flex in the system and the bit tends to bounce off the edge of the aluminum rather than biting into it. Yes, a common trim router will do what you seek. You'll find the Dewalt 611 and the Bosch Colt are the most common ones used here. Getting collets in alternate sizes for them is also fairly easy. As for the laser idea,... not for aluminum.
Let me add that the machine you are thinking about will not be able to use a laser powerful enough to cut Aluminum, and I have serious doubts about laser cutting 3/4" plywood. The lasers that you might mount on this sort of frame would be less than 5 watt, which can cut very thin wood, it would take a lot more passes to cut such thick stock. Even laser cutters which sell for thousands cannot cut metals. Your ability to cut on a pre-folded chassis will be limited by how well you can clamp the chassis onto the cut board. I really wonder how well this will work unless you have some blocks inside the chassis to support it.
