Just for the heck of it, I went out to the garage, found a chunk of scrap brass, 1"w x 1/4"thick x 4" long. I took out a 5/32" 4-flute end mill and then headed in to the basement to dado out a groove in a chunk of scrap pine. Here's the results.

The pictures are :
1) the setup - metal can't lift or fly out of either end
2) milling bit and workpiece are securely clamped in a sandwich and in the spindle
3) the finished milled slot - 1/2" long - took about 30 seconds in this 1/4" thick stock

I didn't bother to research cutting speed, but the press was set at 480rpm for a circle cutter bit and it "seemed" about right. It cut very smoothly and left nice cool clean shavings.