Today I got to finish the majority of the steel plate I've been working on the past couple days.
Unfortunately, I'm not able to show very much of the project since it's under an NDA. I was able to finish cleaning the top face of the part and came in with a 1/16" square endmill to do an adaptive clearing and contour the small pins on top. Due to how they were located, there a tiny amount of material that couldn't get cut with the 1/2" endmill.
Two features on this part are critical, one hole, and a pocket, which needs to be in tight tolerance to one another. For this, my boss had me boar them out vs. drilling it, which would allow tolerances of plus or minus five-tenths (0.0005"). I didn't think it through properly and started to do this with a six flute square endmill, but stopped the machine quick when I heard a low rumble then crunch. It turns out that with that many flutes, there isn't enough room at the bottom to clear the chips properly, and so isn't ideal for cutting down. Thankfully I was leaving a few thou on the walls, so no real harm was done. I came in again with a four flute endmill and got the holes to within three tenths (0.0003").
From there, I used a quarter-inch four flute endmill to cut the part out of the stock using 0.03" step-downs at 30in/min. I did get a bit of chatter when it was cutting the backside of the piece, but I think that maybe because the flood coolant couldn't reach the end of the tool, and so was dry cutting. I then took a 1/8" ball endmill to clear a bunch of the material away to get a chamfer along the edges. I had to use a ball endmill because there were some smaller features that only a ball endmill could reach, and so would have to do the entire contour of the part with a 1/16" ball. There are some tricky areas to this part, which I may recreate to show some of the difficulties I had to deal with.
Overall the part is coming out looking beautiful, and everything is within 0.0005" (well above acceptable tolerance!), and the finishes are immaculate!