For this lock, used a blank found at a yard sale.
As for why impression? I like the challenge. Just wish I had your talent!
Since you are here, Lauren, that reminded me that I took some pictures of another one of these locks after seeing your writeup on how to disassemble them. Credit for teaching me how to take these locks apart goes to Lauren, folks! It may have been a while, but I don't forget those who teach me!
Adding a few more pictures since there is once more a little more interest in these Yale Push Key Pin Tumbler locks. Had the pictures around a while, may as well post them. Hey, nobody tell Oldfast that there are a few gut shots. Shhh!
The lock is picked open, and the brass fitting is partly unscrewed on the side without the shackle. This is the first step in disassembly.
With that fitting removed, look into the hole. You will see this spring. Have pulled it away from the shackle side of the lock. Then the shackle can be removed from the lock. A plug follower is not a bad idea when removing the shackle.
This is the plug part of the shackle. Pay particular attention to the fourth hole. The fourth hole has a larger diameter key pin which
can not be lifted above the shear line. This works as a kind of adjustable warding. The tip of the key will need to be filed down to this level in order to fit the key fully into the lock.
Pins from the lock. The driver pins are serrated mushroom pins, and the key pins are serrated. There is a bit of wear on these pins, which is to be expected considering the age. The pictures are from my old phone, so you can not see the serrations very well, but all the pins are serrated.
Gordon
Just when you think you've learned it all, that is when you find you haven't learned anything yet.