Master #3UP (universal pin)

[vinnie]

I just took apart a Master #3 universal pin lock, and here's what's inside for those interested! This one has already been set.


how these work:

when you buy a UP lock, there's only 1 pin per hole. The pin is quite long (so when you buy it the lock will not open) and serrated in the mid section. One would insert a desired pre-cut key into the lock. The pins will be pushed to the desired level then the cylinder will be hit with a hammer and the pins will all break at the desired level (that's why they're serrated, so easy to snap).

So before it is set, the pins will look similar to this (still attached as one pin each):




then when the cylinder is hammered with the key inserted, the pins will snap and the bottom pins will all be moved 1 place over so it will result in this:




this means there are now 4 effective pins, and the broken half of the first and last will be inaccessible. Obviously this can only be done once, but it's a neat and easy method to sell locks that one can set to whatever particular key they want. Very useful for commercial purposes.

Fairly straight forward, but figured someone who hasn't experienced one of these locks might find it useful or interesting!

[GWiens2001]

Doesn't that leave a kind of obvious weakness to destructive entry? And not even that destructive, as the origional key would still work, just that it would then be similar to master keying. No, please don't mention what it is on this forum, just if you think it is a vulnerability.

At least the pins would be serrated.

Gordon

Gordon

[Pickmequick]

Doesn't that leave a kind of obvious weakness to destructive entry? And not even that destructive, as the origional key would still work, just that it would then be similar to master keying. No, please don't mention what it is on this forum, just if you think it is a vulnerability.

At least the pins would be serrated.

Gordon

Gordon

Good point!

I was just thinking what a simple idea.

I suppose it would take a great amount of force though as they say you have to whack it quite hard to set it initially?

[lockr]

Doesn't that leave a kind of obvious weakness to destructive entry? And not even that destructive, as the origional key would still work, just that it would then be similar to master keying. No, please don't mention what it is on this forum, just if you think it is a vulnerability.

I'm guessing from the description that once the pins have been broken to create a shearline, it wouldn't be possible to repeat that action to create additional shearlines.

[Pickmequick]

Doesn't that leave a kind of obvious weakness to destructive entry? And not even that destructive, as the origional key would still work, just that it would then be similar to master keying. No, please don't mention what it is on this forum, just if you think it is a vulnerability.

I'm guessing from the description that once the pins have been broken to create a shearline, it wouldn't be possible to repeat that action to create additional shearlines.

Looking at the pins it would be possible but probably far easier to open the lock some other way than to try that way.

[lockr]

Looking at the pins it would be possible but probably far easier to open the lock some other way than to try that way.

Right, sorry, to clarify I meant via the original mechanism (striking the cylinder) that was used to create the shearlines in the first place. Not doubt that with enough torsion on the plug you'd shear the pins again; naturally, this is a pretty obvious design flaw with this lock.

[Daggers]

a short pin would be significantly harder to break than a longer pin though due to physics so it would take a lot more force the second time around i think. Maybe too much to be practical

[lockr]

Agreed... I can understand it's purpose: when convenience is more important than security. But my concern would be if the manufacturer isn't forthright about the security and reliability of such a mechanism.

Also, it seems that in the pictures that the fractures aren't entirely clean. I imagine that a sloped fracture could potentially increase the tolerances, and/or at the very least interfere with the proper operation of the mechanism.

vinnie, before you took it apart, how was the operation of the lock?

[vinnie]

the security flaw of whacking it again to create another shear line is not possible.

When it is first bought before it has been set the plug sits out a little bit so when it is hit it moves inwards so it's flush and there is no more possible room to be hit further in. And the plug cannot be pulled out since the first pin that shears then gets pushed by its spring into a groove around the plug.

here's a picture of it. Notice the groove around it at the right where the first sheared pin gets lodged




and it works like any other normal lock once set. You would never know the difference from normal use.

[LockDocWa]

I have noticed that once these locks are "Keyed"
there is a small "TIT" still left on the pin.
Turning it back and fourth several times rapidly will smooth
this out and allow the lock to open easily.

Of all the master padlocks I have sold thoughout the years
The UP series is the MOST returned and problem prone of all.

I'd be willing to bet, if you had a Master blank made out of
super hard steel, and you put enough torsion on the key
you could create another shear line.

But who has that kind of cash to waste on a super blank for a Master padlock?

[ARF-GEF]

It's not possible to whack it again because you can push the cylinder any more in.
But maybe even if it's harder it's still possible to break the pins with a strong key (cut to any cut) and turning it strongly, isn't it? Also 4 pins, even though serrated is not really secure by any means.
So I don't really think it is a lock for sensitive areas just for a quick change of lock where old keys should be still working. (like when there are 24 cleaners who all have keys and need access to the room where the cleaning stuff is stored. Or when many people who travel in from different places already have the key but the lock has to be changed/new lock installed for the same key and so on.
I really don't think this cylinder is about security it's just very convenient. (and pretty cool from the the technical point.)

Thank you for sharing this lock with us!:)

[vinnie]

I found some literature on this from Master

#10 on page 16 describes it better than I could

http://www.masterlock.com/pdfs/7000-003 ... _13_17.pdf

[cledry]

These are available just to make getting locks keyed to a specific bitting without need to do a factory order.

Master generally has certain limited codes for their KAA locks, anything outside of this is a factory order and they are slow!