straightpick wrote:Corbin-Russwin also had the ball bearings in the pin chambers. While they seem to be there to make key insertion easier, that's not the purpose for them. They are to prevent impressioning a key. The ball bearings will roll and not mark the key with marks for impressioning.
I think the insertion of the key being easier is always based on balanced pin stacks, not on ball bearings. The locksmith who services our entire campus and who is slowly replacing all of our Corbin Russwin institutional locks (which have the bearings) with the Medeco system we have, told me that the bearings are there to slow down the wear on the key pins because the locks are expected to be in place for many years and are used daily by janitors, teachers, IT guys, administrators, security guards. I do have to comment on a post above and say that the ball bearings couldnt in most cases be used to create additional shear lines, the key pins are simply too long and it would be difficult to lift the stack that high as to make the shearline be between the key pin and the bearing.
As for stopping impressioning, I don't know, maybe they do, but I'm not so sure that was their original purpose and design.
Squelchtone