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Locksmithing 101 | Re-keying locks? Don't make this mistake!

I want to discuss a standard locksmithing error that occurs when rekeying apartment complexes, office buildings, or anything that has various doors and a variety of different people who use them. But let's have some fun with it, and I'm going to rekey a Sargent lock.


This is a Sargent rim cylinder that we're pretending we removed from an office building and were hired by the customer to rekey, so I'm going to insert the key, the existing key, and then pull it out. Now, we're going to pretend that we've changed the bitting on this and then reassemble it. We're finished.


Did you make my mistake? Did you notice what I missed? It appears to be a standard internet rekeying job for the most part. However, I omitted one critical step, which was to check for existing master pins. When you're out rekeying or master keying existing locks that have even the slightest possibility of being master keyed in the past, it's critical that you check for existing master pins to avoid future security issues like cross keying and keys that work but shouldn't.

Let me rekey this cylinder again, doing it the right way, the proper way to rekey this cylinder. Once again, I'm going to take my existing keys, I'm going to put it in I'm going to put the follower in here, and then you know this is the point where you'd rekey the cylinder, but now we have to make sure that we're checking for the existing master pins. Start by taking an ordinary follower and a pair of pinning tweezers. Put your finger on it just to spread them out like this, and then you must go one by one here, go three on one side, two on the other and check for these. So take it back one, I'm putting my tweezer top right over the top of it, so everything doesn't go flying in.

There we go. Therefore, there is a master pin, and I will gently slide it back up. As you can see, I extracted the single master pin. Now, you must proceed through each chamber individually, which is a little tricky if you've never done it before, and it's a little more time-consuming. It's easy to make a mistake and then find yourself rebuilding the entire guts of this thing.

Therefore, there is an easier way to do it; allow me to demonstrate. Allow me to proceed, and I'll reassemble this in a moment. To begin, I'm going to take this PRO-LOK master pin follower, part number LT370. As you can see, the front here is like a standard plug follower, but the back here features this unique milled-out section. Acceptable. What this does is allow you to drop them, to move this cylinder down over the cutout, and it's designed in such a way that all of the master pins will rock back and forth, and all of the master pins will fall out, but all of the top pins will remain intact. It's a tremendous time-saver.


Allow me to demonstrate how this works in this case. Therefore, we're going to use it just like an essential follower upfront; we're going to align it and push it in just like this. To begin, we're going to remove our plug and set it aside. Now, as you can see, it's just like a regular follower up to this point right here, but we're going to slide it down over the cutout portion. Now, as I do that, keep an eye out over here on this side because you're going to see master pins emerge. Now, let us begin. That is correct.

As you can see, they have all started to emerge. Allow me to enter, and I'll dump those for a moment here. Once you've secured it in place and the master pins have been removed, you want to rock this back and forth. When you do that, it ensures that any of them trapped inside will come out.

If you look at this ankle here, you can see all the top pins are right there. They're all still intact; everything is just fine. It just allows the master pins to come out. When you're done rocking it, and you have them all out, all you have to do is twist this follower just like that, and you can move it back over to where you started, and when you're done rekeying it, you can take this and put it back together. And at that point, you know with certainty that all the master pins---existing master pins that were in here are now gone. So that is the proper way to do it.

Let's make sure that we're avoiding this major mistake, and we're checking for existing master pins. I'd love to know in the comments below. Tell me, do you guys like using just tweezers to check for those master pins, or do you like using a tool like that PRO LOK LT370 master pin follower? Let me know in the comments below. Thanks, and we'll see you next time!

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