Replacing an Entrance Door Knob with a Yale YDM 3109A Digital Lock

In this job, we replaced an old entrance door knob with a Yale YDM 3109A digital door lock 70mm backset mortise.

The original door knob was a standard tubular latch lock, installed with a 70mm backset and a 54mm bore hole.

To make the upgrade work neatly, we used the 70mm-backset version of the Yale 3109A, which helped cover the existing bore hole and gave the door a clean finished look.

This was not a straight swap. The Yale 3109A is a mortise-style digital lock, so extra work was needed. We cut a new mortise pocket into the door, drilled the required holes for the new lock body and fittings, and also prepared the door frame to suit the new strike plate.

The result is a cleaner and more modern entrance setup. More importantly, the door is now more secure and much more convenient to use, with PIN code and RFID tag access instead of relying on a standard key and knob.

If your current entrance door has an old knob or tubular latch, there may be options to upgrade it to a digital mortise lock like the Yale YDM 3109A. Compatibility depends on the door material, backset, existing holes, and frame setup, so it’s always best to check carefully before choosing a replacement lock.