Bumpkey Proofing Locks.

[mh]

i was just looking at another thread
and followed a link to deviating.net

has anyone heard of shallow drilling

http://deviating.net/lockpicking/08.24-shallow04.html

Although many people say so, I would not agree to that this makes a lock 'bump proof'.

IMHO, bumping means opening a lock with a correct blank that's cut with the maximum cuts for that cylinder.

Well, for a cylinder that's drilled "shallow", some positions have smaller maximum cuts, that's all.
One could easily detect that with a hook pick, and then cut another bump key.
Cylinders with "shallow" pins in different positions are just like variations in profile; they require more different bumpkeys (that's inherent in the bump key opening concept anyway, you need lots of different bump keys), but that's it.

To me, claiming that such locks are bump-proof means to limit the bump key opening concept arbitrarily to "All-9-cut-keys".

[maxxed]

I considered another alternative, two top pins. The lower of the top pins would be sized to match the bottom pin so that the combined height would be just .030 - .040 higher than the shear line, the second top pin would sit on top of this stack. If the "pool ball effect" works by transfering the kinetic energy to to final pin, then only the upper top pin would move and the lower top pin will block the shear line. I will try this tomorrow and post the results.

[maxxed]

After testing my above mention theory I must admit it did not perform as expected. The lock did take a few more strikes to open but that was all.

[Raccoon]

Shallow drilling a lock is not a valid solution. At least not if the pins are ever going to be changed.

By shallow drilling a column, you are limiting the biting depths allowed for that pin stack. So now you're left with a cylinder capable of 1-1-1-1-1 through 6-6-6-4-6. What happens when you want the 4th pin stack to be 5 or 6 deep?

You can't just sell one kind of cylinder now-- you have to make 5 different cylinders, each with a different column drilled at a different depth in order to make it somewhat difficult for bumpkey prediction (oh, lets just leave the 4th biting at 4 deep). The manufacturing and maintaining of these additional cylinders adds extreme overhead.

Now you have 5 or more cylinders floating around on the market. Lets say I'm doing a master-keying job for a campus with 5000 locks. Do I really want 5000 locks with a possibility of 1 of 5 different cylinders being in these locks? What when I have to change keys for a particular lock, and suddenly nothing fits in with my mastering system? I'll just have to pull every core and figure it out again from scratch. Ok, worse case and very improbable scenario, but still another hassle to deal with.

Really, the best solution is something that can retrofit an existing lock (at least keeping all the main/expensive components). If someone could come up with a pin solution to thwarting bumps, it would be embrassed by all.