Sizing Cylinders for Hollow Metal Steel Doors: Internal Stiffener and Mortise Offsets
Engineering Overview: Technical guide on sizing commercial 1-3/4" (44.5mm) hollow metal steel door cylinders, evaluating internal channel stiffeners and lockcase offsets.
Technical & Engineering Specifications
| Application | Commercial High-Rise Stairwells, Exit Doors, Plant Rooms |
|---|---|
| Door Standard | ANSI / SDI 100 Commercial Hollow Metal Doors |
| Door Thickness | 1-3/4 inch (44.5 mm) Standard |
| Cylinder Specifications | 35/35 mm Euro Profile or 1-1/8 in Threaded Mortise |
Commercial Hollow Metal Door Standards
Standard commercial steel doors are manufactured to 1-3/4" (44.5 mm) thickness per ANSI/SDI standards.
Mortise Lock Alignment
- Centered Mortise Cases: Standard ANSI mortise lockcases are centered, specifying 35/35 mm (70 mm total) Euro profile or 1-1/8" (28.5 mm) US threaded mortise cylinders.
- Reinforced Escutcheons: Heavy commercial 12 mm armored security roses require expanding the external segment to 30/40 mm or 35/45 mm.
Frequently Asked Engineering & Selection Questions
Q1: What size Euro cylinder fits a standard 1-3/4 inch commercial steel door?
A 35/35 mm (70 mm overall) cylinder fits centered mortise cases with standard escutcheon plates.