Here you can see what I was talking about on the last page. Once both pieces of the hinge are parallel with each other, there is a gap. I placed the cardboard between the sides of the hinge to show you what I'm talking about. But I'm also going to use this cardboard to help me machine them as well.
 

What I plan on doing is rounding the corners of each one to make it easier to fit into the pocket that I'll be cutting for them. Now I realize that I could have used a hammer and chisel to make square corners in the pocket without doing any of this. However, this process goes fast because the radius is small which means I can take just one cut here.
 

Here I'm doing some testing before I cut the pockets in the real pieces. After a few different tries, I found out that the way these hinges work isn't what I thought. That meant I had to use slightly different depths to have the two pieces close properly. That's the good news, the bad news is that I wiped out a few of the screw heads in the process because of how many times I installed and removed them, along with how soft they were.
 

What you see on the left is the #2 screw that came with the hinges. However, I messed up about half of them as I was doing the testing. The one on the right is a #3, that I bought from the hardware store and I would've bought the #2's but they didn't have that size.

I'll need to fix a couple of things to be able to use the new screws. First you'll notice the full threads on the smaller screws, compared to the other one that has a small shoulder, which is typical of wood screws. However, this will not screw into my work piece like this so I'll have to modify the pilot holes slightly to accommodate the difference.
 

I used one of the pockets in my test piece to trap the hinge so it didn't spin. I held one side with my hand while I enlarged the countersink. This worked out but I kept a keen eye on things while I was doing this.