If you look back a post, there's a 3D rendering of the design. The base will be milled from 1/2" aluminum plate. For all three pieces I'm using a basic "profile" cut: the drawings are simple 2D shapes and the cutter runs around the shape with an allowance for the width of the cutting bit. Depending on the material and thickness, multiple passes at increasing depth may be used.
You have to account for the cylindrical shape of the cutter when designing your parts. The "sun" is just a circle, there are no inside corners. For something like an L-shaped piece, there's one inside corner. You can't make a perfect square corner (if you are cutting from the top), it's going to be curved like the cutting bit. So the smaller the radius of the cut, the closer you can conform to the actual shape.
In designing the base, I planned for a 1/8" diameter cutter, so the inside corners already have a 1/16" radius. I have a 1/8" cutting bit with a 3/8" depth of cut. This worked well for the sun and the bird, but the base is the full 1/2" of aluminum. I looked around a for bit with 5/8" DOC, but couldn't find one. I bought a Dremel bit at Lowe's that has pretty long cutting flutes. It doesn't really look like a milling bit, it's got like 8 flutes or something. Suitable for very high-speed work perhaps, finishing but not so good for roughing. It should do the trick but I will have to be careful and make multiple shallow cuts.
For the sun and bird, I worked with a large rectangular piece of stock held down to my tooling plate with some simple 90 degree clamps (designed to hold my vice) with a piece of sacrificial stock underneath. The NC program just cuts the part out as you might do for balsa wood sheet parts for an airplane. Since the base piece is 1/2" aluminum and the Dremel bit won't plunge cut, I'd have to rough cut with a much larger bit. I don't even have a suitable 1/4" bit that will do 1/2"+ DOC. I decided I didn't want to waste that much material. Better to start with a piece just a little larger than needed and trim off what you don't need.
With profile cutting, you eventually remove all the material between the piece you want to keep and the part you don't. The clamps are holding down the part you don't want leaving the good material to fly free just as you are trying to finish the cut. I used two techniques to hold down the good part. First I glued the aluminum sun to the sacrificial backing with Gorilla glue. This worked really well, but required power sanding to remove the glue. For larger pieces this is probably a good approach. With the bird (plastic) I used the "tabs" setting in the CAM program to leave material in a few spots to hold the good to the waste. This also works well, but requires extra manual work to remove the tabs. I need to get better files for this technique to provide a good finish.
For the base, I need to hold the part down from one side, cut the shape on the other side, move the clamps from one side to the other (without ever leaving the piece free to move) and then cut the second side. I don't really have good clamps for this. I considered buying a clamping set but decided my shop philosophy would be to make whatever I can and buy what I can't. I need the experience making things. I thought I'd make this clamp. It's a similar part to my base piece, meaning I don't have clamps to make the clamps. So I came up with this design for a simple strap clamp suitable for the size of my mill:
This is a bottom view, the shoulder in the upper right is designed to provide some lateral resistance. There could be some slippage between the clamp and bolts, we'll see. Here's the first one I made:
The bolt on the left runs through a threaded hole and pushes the clamp up, the bolt on the right runs in the slot and pulls the clamp down (via the threaded hole in the plate). I'm using the Popsicle stick to keep it from scratching the plate. I gave it a moderate tightening and it's quite strong, just the one! Four should be plenty strong unless I get super aggressive hogging material off with the 3/8" cutter.
I cut the stock for this clamp with a hand hacksaw in my bench vice. It was quite a bit of effort. I haven't done a ton of aluminum work over the years. I expect this to change now with CNC power. Manual stock rough cutting is going to get old pretty quick. A floor-based horizontal bandsaw is the common tool for rough-cutting stock, but I don't really have the space for one. Also I've gone many years without a reciprocating saw ("Sawsall"). So I bought one. A reciprocating saw is great for cutting 2x4's and such, things you can press the front plate against. Small parts in a small vise are not so easy.
I interrupted my clamp making to make a couple jaw inserts for my vice:
This provides a nice "fence" to run the saw against, cutting horizontally. Now I can get back to cutting the stock for the other clamps. Then I can get back to making the base of the KFM logo.
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