It's important for me to get my custom car "right". Right means it fits my vision of what a beautiful car should look like... Beautiful being a qualitative term of course.
For me, simple grill work like those found on ferarris defines what looks best. Unfortunately, locating the perfect material to shape one proved to be overwhelming.
Sheets of punched aluminum are available and easy to come by, but I was looking for aluminum sheet with closely spaced punched aluminum holes and what was available had spacing neither good looking nor efficient for air flow.
The formula used to make commercially available sheets dictates the distance between holes is no smaller than the hole's radius. This is solid engineering principle, but a grill isn't exactly structural, so in this instance, engineering principles can be ignored.
The sheet metal I chose is .125 thick. By using such a heavy sheet, the reduced distance of aluminum between holes can be offset by thickness and helps the rigidity of the aluminum greatly (OK, so engineering principles do apply)... A thicker piece will also show off the machined holes much better.
The material I chose had .250" holes and the spaces between them were .125".
Increasing the hole size to .312" would reduce the theoretical gap between holes to .062". In my case, the actual finished gap ended up being closer to .070". Apparently, manufacturers stated hole and gap sizes aren't all that precise.
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Step 1: Setting the Work Up
The first thing I did was to cut the grill to shape. The opening at the rear of my car and the hood radiator egress vent use the same material, so I also cut and formed those as well.
Using one of the holes at one end of the aluminum plate, I fixed it to a block of wood with a drywall screw. I placed the screw on the centerline, at the end of the block closest to the furthest end of the grill. I'll explain why later.
My belt sander sits next to the press, and I used it to hold a support that kept the wood block flat on the drill press's bed.
And using an old can of wax dedicated to non-car shining projects. I cut a block of the stuff out and spread it over the aluminum plate in the area I was about to drill. You only need to insure a small amount of wax is shaved off and ends up inside the holes, either along the edge, or as a lump inside. Oil could also be used, but wax is easier to apply, clean up and far less messy (If you use oil to coat the table of your saw and other shop tools, you'll find that over time, it turns the steel black. Wax is better. It protects from rust, lubricates the bed and stays clean. You'll thank me for this later).
Oh, and after the wax in the can gets chewed up, a quick pass with a heat gun will smooth it out like new again.
Step 2: Tooling the Grill
When that section is done, remove the screw and move it to the block's opposite side and repeat the same process over until you reach the end of the grill. Don't forget to drill the holes the screw is removed from.
The milled, billet look is very impressive. In my case, the grill will be painted or powder coated black, so the tooling won't be noticeable. But still, it'll be impressive none the less.