Attaching the other T-nut here does the trick.

Turn the carriage bolt into the T-nut.

Drive the T-nut into the hole.

The eight-sided T-nut base has become the standard configuration for T-nuts inserted by machine.

No special T-bolt or T-nut required.

Be sure to countersink the T-nut from the top, so the tripod pulls the T-nut down onto the bottom board.

A T-nut, T nut, or tee nut (also known as a blind nut, which can however also refer to a rivet nut or an insert nut) is a type of nut used to fasten a wood, particle or composite materials workpiece, leaving a flush surface.