This has been called a lockout key or a witch key. The purpose is to lock out a tenant when they don't pay the rent. OR something similar. by law you cannot enter the rental unit to change the lock, and this allows you to lock out the problem without entering the premises.
The pair are hand made - so look at my witch key and take notes of how it is made. You will need several key blanks to get this right, so take your time. Once you get the thing down, you can make more quickly, but it is that first one which will take sometime to craft.
Start with the lower piece. this is a actual lockout. You need to remove most of the key blank down to the #8 cut for the first four cuts, leaving that hook on the end to capture the 4th pin, and lock up the piece in the cylinder. Note that you also need a steeple or ramp on the end pointing to the front so you can slip this under the pins when removing it.
The next problem is solve is how far this goes into the lock. You need a stop on the front end so the thing won't get shoved all the way thru the lock - here is the problem. AS shown in most books there is a "tail" sticking out which some problem will try to pull out using a piers and breaking the thing off, and making a worse problem. Here you need to work carefully, and find out just how much of that bottom edge you need to keep from going into the lock, and how much you need so there is nothing sticking out. Once you find that you are half way home.
Now how, without a "tail" to grab can you get the locking piece out?
Into making the top part.
First shave off most of the bottom of a blank leaving the other half like it originally was - and fit the front into the hook so it snuggles into the lockout part. Now - before you go and totally shave off the blank we need to get an "extractor" built into the top part. Here you need to fit things carefully.
NOTE the difference in the heights of the two parts and how they fit together -- now, at the front end you are going to leave a "pin" or finger sticking down. It should be about .060 in width, and about .030 deep, and about 3/32" if an inch "in" from the end of the lockout piece. Carefully figure out where this has to go - and then shave off the top part leaving that pin sticking down.
ON the bottom lockout piece, make a pocket about .060 where the pin sticks down. Now the two should interlock when in the cylinder.
The way this works is this, and you will have to fit this carefully - insert the lockout part. Then slip in the top. Pick up on the bow as the pin goes in, then once it is all the way in (as you fitted it) push down. this should engage the pin the the pocket, and then simply pull gently and the two should slide out of the lock. It may take some time to get this right, but when it does it works so slick!
No tail sticking out, nothing to force in or out, and the removal is so slick that the tenant won't know how you did it.
Try it!
I may make up a drawing from my notes and post it later - but for now --
Sinifar
