Keyhole retainer

Vertical keyhole mounts work great because gravity keeps the mounting bolt in the narrow portion of the keyhole so the item doesn't fall, even when the bolts are loose.

Keyholes are less safe for horizontal mounts such as on the ceiling, since there is no natural tendency for the bolt to remain in the narrow end of the slot. Worse, when tightening the bolt the rotation has a tendency to walk the hung item along the keyhole slot.

This retaining clip locks the bolts into narrow end of the keyhole slots, making horizontal mounts safer. They are designed for a specific overhead power cord reel but could easily be modified for any keyhole mount.

The dimensions of the keyhole in this case are:

• 19.5mm for the large hole.
• 10.2mm slot width
• 35mm total slot length

It was a conscious design choice to make the hole in the retainer the same size as the slot, which is much wider than the bolt that I used. This allows for some slop in the distance between centers of the mount holes when drilling.

After mounting the overhead cord reel I noticed one thing that would improve the design and which I'd change if I had to do this again. The width of the retainer was sufficient to contain the bolt hole and the key plug in their proper positions. Unfortunately the mounting plate I was attaching to the ceiling is wider than the retainer. Since the retainer holds the mounting plate 3mm away from the ceiling, this allows the mounting plate to wobble. Were I to redesign this I would extend the width of the retainer to match the mounting plate. If I were really ambitious, I'd combine two retainers into a single piece whose outline matched the mounting plate. That way I could use the holes as a drilling template.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/afCU1Ehg1gW

Category: DIY