The Crankshaft lock design

[Yehonatan Knoll]

A combination is pickable by a (sufficiently stiff and thin) L-shaped tool, if and only if it does not have both maximal right and left wafers. If - because you then have a relict path for the tool right along the centerline.
Only if - because otherwise the long leg of the L-tool must be inserted at an angle relative to the centerline, hence its short leg, when rotated, traces a plane which is at an angle relative to the plane of any wafer.

[prevariikation]

Only if - because otherwise the long leg of the L-tool must be inserted at an angle relative to the centerline, hence its short leg, when rotated, traces a plane which is at an angle relative to the plane of any wafer.

I'm making an optimistic guess, for sure, in assuming that the plane mismatch can be compensated for by a skillful picker (with locksport time on their hands.) If there's more of the keyway to work with, as well, the tool may be able to be inserted a little deeper and the tip curved back toward the picker to allow some movement through the wafer's plane.

Some graphical explanation of the algorithm, for fun:

Can a vertical tool be used to pick a bitting of 21234?

Identify all keyway contact points (note the two extra points at the bottom, because we need to be able to reach into the wafer's rest position.)

Take the contact points furthest into the keyway (not necessarily unique.) Clearly there's no horizontal distance between these points and a vertical tool can't be used.


Rotating by 15 degrees actually allows a vertical tool, though, which is the same as a tool inserted at 15˚.

Obviously the image is misleading as it would be a *very very* thin tool subject to bendiness.

[Yehonatan Knoll]

Nice
Practically speaking, the false gates render moot the distinction between pickable and unpickable combinations.

[prevariikation]

True I mostly made it for pictures to stare at! Locksport is an expensive hobby and it's cheap and fun to theorycraft