Surface motor on a deadbolt turn-piece
An adhesive or screw-fixed motor sits on the door face and rotates the existing deadbolt turn-piece. Nothing is drilled. This is the standard approach for North American single-cylinder deadbolts and for many Asian rim deadbolts.
Applies to these lock types
Single-cylinder deadbolt (ANSI/BHMA A156.36) · Rim nightlatch (surface-mounted) · Japanese mortise case and cylinder (MIWA / GOAL style)
Measurements this architecture needs
- Interior thumb-turn / turn-piece size and profile
- Door thickness
- Clearance between door handle and gate handle
Adapter interfaces to design
- Turn-piece adapters: round knob, T-bar, thumb latch, coin-slot
- Adhesive that survives 40–60 °C door surface temperature and 90% humidity
- Alignment tolerance for a knob that is not centred on the bore
Design targets
Targets marked "from standard" come from the cited document. Targets marked "practice" are our engineering guidance and must be verified for your design.
| Target | Value | Basis |
|---|---|---|
| Output torque | ≥ 1.2 N·m |
from standard A156.36 maximum key/turn torque for auxiliary locks. |
| Adhesive peel strength | Design for a 60 N door-slam reaction without creep |
practice |
Known blockers
- Painted or textured doors defeat adhesive — offer a screw mount.
- Turn-piece geometry varies more than any other interface; this is where adapter SKUs multiply.
- Tropical humidity is the main cause of adhesive failure in Southeast Asia.
Design checklist
- Ship a physical turn-piece gauge, not a printed ruler.
- Age-test the adhesive at 60 °C / 90% RH for the target market.
- Make sure the motor body clears the frame stop when the door closes.