A router with a trammel base and using a 1/4 inch bit will cut perfect holes of any size quickly in aluminum. You can buy a trammel base or make an acrylic base for the router and drill a 1/8 inch pivot hole in the base at the proper radius. A trim router is a perfect size to use and you can buy one for about $25 bucks at Harbor Fright (intentional mis-spelling.) If you want to spend a few more bucks, get one with a plunge base. Secure a sacrificial piece of ply or particle board under the aluminum panel sheet and make sure the hole for the pivot pin goes through the aluminum and well into the sacrificial piece. I use a couple of pieces of double side tape to stick the portion that will be cut out to the underlying particle board. This keeps the cutout from rotating wildly as the bit finishes the cut. This will give you holes that are the equal of CNC holes. Always cut a test hole in scrap to make sure your technique and measurements are correct. For .125 I would make several slow shallow passes. If you are cutting instrument holes in 1/4 inch ply--a Dremel tool with 1/8 inch router bit has enough power to rout them. I use this setup for cutting sound holes in ukuleles. Be careful, move slowly and use eye protection whenever using a router.... and.... clamp the assembly to your table to make sure nothing can move. . Rich Hartwig Waunakee WI
