Stepped Paracentric Keyways: Deflecting Bump-Key Shock Waves
Engineering Overview: Mechanical analysis of stepped paracentric keyway broachings, analyzing vertical centerline offsets and kinetic shock wave dissipation against bump keys.
Technical & Engineering Specifications
| Standard | EN 1303:2015 Key Related Security Grade 6 |
|---|---|
| Protection | Anti-Bumping & Covert Pick Obstruction |
| Keyway Geometry | Paracentric Centerline-Crossing Broach |
| Kinetic Dampening | > 70% shock wave deflection |
The Physics of Kinetic Lock Bumping
Lock bumping relies on transferring an impact shock wave from a specially cut 999-key to bottom pins. In straight vertical keyways, this shock travels unobstructed along a straight vector, throwing driver pins across the shear line.
Paracentric Geometry & Wave Dissipation
A Stepped Paracentric Keyway features interlocking side ribs that cross the vertical centerline of the key slot:
- Centerline Offset: Bottom pins rest on an angled shoulder rather than a vertical flat plane.
- Kinetic Dissipation: When a bump key strikes, the shock wave deflects laterally into the brass plug walls at 30°–45°, dissipating over 70% of impact energy.
- Pick Obstruction: The convoluted profile prevents straight lock picks from accessing pin tips directly.
Frequently Asked Engineering & Selection Questions
Q1: How does a paracentric keyway stop lock bumping?
Its curved, centerline-crossing shape deflects the kinetic impact wave sideways into the plug walls, preventing pins from jumping across the shear line.