Nielsen Latch locking nut

This locking nut is designed for the common Nielsen latch 83314-LALB. It is commonly used in battery tanks for technical diving which you carry on your harness. While the latches already have a locking mechanism they are still prone to accidental opening when they are free to move around and hit other objects.

Simply put two of these nuts on a tight bungee loop and put them on the battery tank like shown in the photo.

There are two sizes available which only differ in the thickness of the straight section that goes into the Nielsen latch. You can easily tell them apart by the holes on the back side.

Source models for FreeCAD are also available for download if you need to modify them (V1 only).

ChangeLog

v2 - 2024-11-23

Added an improved version that does not come loose so easily. Each lock is mounted individually. Put a 150 mm loop of 2 mm bungee cord through the holes and pull it over the Nielsen latch when closing the tank. The number on the back indicates the size.