The wife has been skeptical of the mill purchase (Sieg X3) since it arrived last year. Too big, you don't have time for hobbies, looks like the drill press you already own, etc. However yesterday she said, with no prompting from me, "Thank goodness for the mill." And for this humble project, started and completed in a few hours.
Problem was an unusual double-sided lock on a heavy-duty screen door...no key to it when we purchased the house. When I took it to the locksmith he said, "There's no way to get those open to re-key them. You have to buy a new one. $100, and I'll order it." (The one he wanted to order had slightly different dimensions.) Problem is, you can't pick and rekey it with a follower because of the opposing cylinders. Standard follower method would work for one side but not the both simultaneously.
$100 seemed like too much expense with no guarantee of success. After contemplating it awhile, I decided to mill off the top of my existing lock, to expose the holes. Then dump the pins out from the top. That unlocked the plug from the hull. I knew I'd have to put a top back on the pin holes somehow, and decided it was easiest to sacrifice a pin hole. I chose the last pin hole because it had the most metal around it, even though choosing the middle pin hole would have been more elegant. Potentially, with a shallow-enough thread, and clever combination of pins, and a shortened spring, it's possible no holes needed sacrifice. I didn't go for elegance here, I was bent on speed, and was willing to sacrifice one pin's worth of security on a screen door.
Next came (for me) the difficult part. Making a thin top for the pin holes. I had some .030 shim stock on hand and made mine of that, cutting it out with a jigsaw and then using my belt grinder to get the final shape. Didn't seem like the best solution, what would you guys have done? I didn't machine a top because I didn't think I could put a full-width (.090) top back on it...was afraid that would put the screw heads too high.
With the plug out I chose a pin configuration that was pick-resistant (a configuration that's roughly the opposite of most lock picks) and cut my key (with a hand file...figuring out how to do it on the mill seemed too cumbersome, and I didn't have the right sized ball end mill anyway...but there's no reason a mill couldn't make a dandy key cutter). Then I filled the plug's pin holes to the top with graphite powder and slipped it into the hull. Top pins and springs went into the top, then the hole cover got screwed on. Last operation was to shave off the heads of the screws so the profile would fit into the door.
Back in action (minus one pin; it's now a 4-pin lock) and the wife approves!
