Tool
Master key plan generator. Every symbol says where its key sits.
The symbols follow the keying nomenclature of the North American door-hardware trade, reflected in BHMA A156.28. In a four-level system the top key is GGM, grand masters are A and B, masters AA and AB, and change keys AA1, AA2. Read AB2 from the left and it says change key 2, under master AB, under grand master A.
Most buildings need three levels at most. Add levels only where the organization actually delegates authority: every level costs capacity on the keyway.
13 key symbols · 10 change keys
13 key symbols · 10 change keys
| Symbol | Key | Also opened by |
|---|---|---|
| GM | Grand master | — |
| A | Master | GM |
| A1 | Change key | A · GM |
| A2 | Change key | A · GM |
| A3 | Change key | A · GM |
| A4 | Change key | A · GM |
| A5 | Change key | A · GM |
| B | Master | GM |
| B1 | Change key | B · GM |
| B2 | Change key | B · GM |
| B3 | Change key | B · GM |
| B4 | Change key | B · GM |
| B5 | Change key | B · GM |
Symbols only. Each master level and each cross-keyed door removes bittings from the pool, so confirm the plan against the platform before cutting.
Ours published as able to be master keyed
56 in our catalog
Backset 60/70mm
Lever Handle
Model 3431 SSET · Video
Zinc Alloy
Backset 60mm / 70mm adjustable
Tubular Lock
Model 575 ABET
Stainless Steel
Light Duty Cylindrical Lock
Model 578 ACET · Video
Stainless Steel
Backset 60mm / 70mm adjustable
Black Tubular Lever Lock Set
Model code to be confirmed
Zinc Alloy
Backset 60mm / 70mm adjustable
Stainless Steel Lever Handle Lock
Model code to be confirmed
Stainless Steel
Backset 60/70mm
Lever Handle
Model 6491 SNET · Video
Zinc Alloy
Before a cylinder is cut
Send the plan with the door schedule: door numbers, profile, length and split per cylinder, function, and how many copies of each master key. Whether a platform can carry the plan depends on its own mastering rules, so the hierarchy is confirmed by whoever designs the system.