FLW400 Underwater Light Cold Shoe Mount

Compact cold shoe adapter for the FLW400 underwater dive light.

Designed for a secure and low-profile fit with a dedicated 18×18 mm cold shoe foot. The adapter consists of two main parts: the cold shoe mount and a knurled locking ring. An optional thumb screw is also included.

This is a replacement part modeled after the original FLW400 mount. The original cold shoe interface is non-standard and specific to the FLW400 light. I designed this adapter after breaking my original mount and being unable to find a replacement.

While redesigning the mount, I also added a securing screw to help prevent the cold shoe from accidentally sliding out of the rig’s socket during use. This makes the setup more reliable, especially for underwater camera rigs where losing a light can quickly end a dive. The securing screw can be tightened by hand or with a small coin. To use the anti-slip securing screw, a 6.5 mm hole must be added to the original rig socket, if it doesn't have one.

Assemble tip: For improved grip and to protect the surface, place a thin rubber or silicone washer between the clamp ring and the device as you can see on the pic.

To improve overall rig safety, I developed an additional tether mount for backup retention. Available in my other project: “Cold Shoe Safety Leash Adapter”.

Dimensions

Cold Shoe

• Overall height: 19.1 mm
• Foot: 18 x 18 x 2 mm (standard camera cold show)
• Top foot: 11.4 x 7.8 x 3.0 mm (non standard FLW400 mount)
• Thread: M18 (Ø 18), pitch 2mm (thread part length: 10mm )
• Bottom hole thread: 1/4"-20 UNC (standard tripod mount, depth 6 mm)

Clamp Ring

• Overall height: 8 mm
• Ring Ø:  27 mm
• Knurled ring part height: 6 mm

Securing screw

• Overall height: 11 mm
• Knurled head part height: 3 mm
• Coin-slot width: 2mm
• Thread: 1/4"-20 UNC (standard tripod mount)

Project / Filament

• use PETG (originally printed with “eSUN PETG+HS”, black)
• reduce speed and increase infill for quality PEG print
• do not use supports