I have a key I want to duplicate. It is not common so with your help I have found out what the blank is and have some on order. I was advised not to take it to my local hardware store for duplication. That makes sense, Locksmiths know things and have experience. (Years ago I was that kid working at the hardware store making keys, I didn't know much.

BUT I like to learn things, I had to buy more links then I need so I want to try duplicating one myself without a machine. I am not trying to save money, I am trying to learn and have fun.

Here is my plan. Clamp the good key and the blank in a machinist vice lined up correctly on top of one another.
Carefully scribe the cuts of the good key on the blank.

Remove the good key and set it aside. Clamp the blank in the vice and mill away excess metal that I can with a small end mill.

I have measured the cuts in the key and they are .062 R so using a 1/r dia round file, file to the scribe lines.

Use a small flat file to get the tip and the approach from the shoulder.

Debur the key.

Try it.

Drive to a locksmith and get a key made.

What am I missing? what do I have wrong?

Thanks