A fastening nut device for fastening one substrate to another includes a cylinder, which is circumferentially larger proximate to a first end thereof, thus defining a first section and a second section of the cylinder. External threading, which is reversed, is positioned on the second section and extends from a second end of the cylinder. The cylinder can be inserted into a first hole positioned in a first substrate by counterclockwise rotation. The first section of the cylinder abuts a first face of the first substrate and the second end of the cylinder is accessible from a second face of the first substrate. A channel, which is internally threaded, extends into the cylinder from the second end. A threaded fastener, which is engaged to a second substrate, can be inserted by clockwise rotation into the channel to engage the second substrate to the second face of the first substrate.