Drilling custom frame

[Espeefan]

Without any fancy tools, this is how I would do the holes in the top of the webs. Clamp the two new frame rails back to back, with the webs facing outwards from each other. Measure the distance of the holes on the stock frame rails. Measure and mark the hole locations on one of the new frame rails. Take a combination square and use it to scribe a light line (perpendicular) across both frame rails. Once you've got the lines marked, unclamp the rails. Set your combination square to a depth that is exactly half the width of the rail web. Go back to all the first set of lines you scribed, and using the square set to half the width of the web, scribe another line that intersects the first. Where the lines cross center punch the hole locations. All that's left to do is drill out the holes. Start with a small drill bit so you can drill pilot holes. Larger bits have a tendency to walk in aluminum. Smaller bits will keep the hole more accurate. Once the pilot holes are drilled, go back and drill them with a 3mm drill bit, or a 2.5mm bit for a tapped hole. Use a little cutting oil if you have to. It will help prevent the aluminum from sticking to the cutting edges of the bits. The only other tip I can give you is to make sure your drill bits are always held squarely to the frame rails. It doesn't really matter what you use to drill the holes. You could this with a dremel if you wanted, but of course something like a drill press will give you better results.