T-nut

T-nuts. The left one has been inserted in the wood and a bolt has been screwed in from the other side.

A T-nut, T nut, or tee nut (also known as a blind nut,^[1] 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.

It has a long, thin body and a flange at one end, resembling a T in profile. The flanges of T-nuts often have hooks or serrations on the prongs that dig into a wooden work piece as the bolt is tightened from the opposite side of the piece, providing better retention.

In 1969, the first four-prong T-nut with the eight-sided base was patented. Unlike the standard round base T-nuts, the eight-sided T-nuts can be fed efficiently and reliably via machine. The eight-sided T-nut base has become the standard configuration for T-nuts inserted by machine.^[2][3][4]

T-slot nuts are used in work-holding in machine tools. T-slot nuts fit in T-section slots in the machine work-table and are used in conjunction with studs and clamps to provide flexible means of holding workpieces in place.

Weld nuts are similar in appearance to t-nuts. They lack the prongs which penetrate into wood. Weld nuts are usually spot-welded into place on metal.

References

1. Airfield Models - Threaded Fasteners used in Model Airplanes
2. US 3480061, Leistner, Walter Hermann, "Fastener member", issued 1969-11-25. 
3. Our history, retrieved 2009-10-21.
4. About Sigma, retrieved 2009-10-21.