What are the consequences of using incorrect top pins?

[WOT]

Schlage specifies using #1 for plug total 0-3, #2 for 4-6, #3 for 7-9.

I've seen cylinders combinated with all #2s even for stacks that didn't fall within 4-6 plug total range.

[JackNco]

Well im not sure of Schlages reasoning but I have seen assa doing it even more accurately I amuse its so you cant feel spring tension. it will also be a way of preventing comb picking in many cases.

Then again it could just be a way of selling you more pins

John

[Squelchtone]

its to stop reading attacks.

imagine this..

if all of the top pins in a schlage are a #2 size, then by probing each pin stack one at a time, you can push up on the pins until they stop, and measure the distance traveled. once all 5 stacks are done you have your self a ratio from pin stack to pin stack. since there's no way to know if they used a #1 top pin or #2 top pin, etc, you can make up a key with the correct pattern, but not necessarily the correct heights. so if the real pinning is 64725 the depths you just read could be 53615 or 75836, etc.

by using top pins of various height, you match up short key pins to long top pins and when spread out on the table, all the stacks will measure the same length.

you're right about this also being applied to comb attacks, because they needed long top pins which would never allow the bottom pin to enter the bible all the way, thus still blocking the shear line at least on one stack, if not more, or all stacks.

thats my story and I'm stickin to it.

Squelchtone

[WOT]

By specs an SFIC pin stack adds up to 0.398" regardless of bitting, but this isn't so for Schlage.

Schlage stacks don't come to the same length.

#1 pin is used for #0,1,2,3
#2 pin for #4,5,6

So a chamber properly pinned for #2 will be shorter by 0.030" than a chamber pinned for 0.

#4 is +0.015 cut -0.035 top in, so it will actually actually be -0.02" SHORTER rather than +0.015" taller compared to a stack made for #3 cut.

[Squelchtone]

I doubt it's meant to be a dead on exact number across the board like it is with Medeco and their .515" balanced stacks. And as you know, SFIC locks, especially BEST have really good tolerances, even though we all consider Schlage to have good tolerances, but that's only when compared to original Kwikset or knock offs like Defiant.


I think I had similiar issues with pinning ASSA Twin, because the top pins #A, B, C, D, were meant to cover more than 1 pin height. D did 7,8,9 so you can imagine the stacks were not exactly the same height, but still better than having all C top pins which if bad guys learned of such a pattern in a production lock, would quickly exploit that fact by reading the bottom pins, knowing with full confidence that the manufacturer always uses a C top pin.
(that was of course just an example with ASSA Twin, your milage may vary)


nite,

Squelchtone

[Mutzy]

A large pin stack (#9 bottom pin + Standard top pin + spring) is sometimes too long for the chamber.

If you key up a lock with the first chamber like this, and the last cut on the key is a shallow cut, the key won't enter in the lock. (Or if you reinsert the core with the key in it, you can't remove the key. Staggering the top pins allow a degree of uniformity across the chambers.

(Stops reading attacks, but also prevents springs from being crushed.)

[WOT]

Do you really feel that it is to thwart reading attacks? That's an art on its own and with bumping and impressioning being available, I'd think that this would be the least of their concern.

[JackNco]

Not on schlage but possibly on some higher security locks.

[Squelchtone]

I remember someone saying that even on a lower end lock like Schlage balancing the pin stacks provides the user with a uniform and consistent feel during insertion and withdrawl of the key during daily use. So not all features of a lock are meant to protect from attack, some are just asthetics and end user comfort.

Someone mentioned springs, and I believe this would also provide for even spring wear during the life cycle of the lock.

Squelchtone