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What Is a T-Slot Nut?

Paul Scott
Paul Scott

A T-slot nut is a fastener used in a series of adjustable mounting systems utilized to secure machine tool vises or to erect modular constructions. These are two-part systems that consist of a T-shaped metal nut with a threaded hole passing through its vertical axis, and a similarly-shaped slot cut into a machine vise base or construction member. The nut slides freely along the slot, which is open along the top of the leg portion allowing a bolt to be passed through the slot and threaded into the nut. This arrangement allows the nuts to be moved along the slots to match the holes in various different size vices or to allow construction members to be adjusted as required. Once the vise or structural member is in the correct position, the bolt is tightened, pulling the T-slot nut up tight, locking it securely in place.

The vises that hold work pieces securely on drill presses, band saws, and routers often need to be moved around in relation to the base in order to position the work piece correctly. Frequently, a range of different types and sizes of vices are also used requiring similar flexibility in the mounting systems. The same flexibility is required in lightweight modular structures such as sound system and lighting racks used in theaters, studios, and on stages. Many of these applications use a system of sliding T-slot nuts and bolts to achieve the required flexibility of movement.


These systems consist of a T-shaped nut that slides along a similarly-shaped slot, allowing it to be tensioned at any position along the slot length depending on user requirements. The T-slot nut system is so named due to this particular nut and slot shape. The nuts are drilled through their vertical axis, in other words through the “leg” of the T and out the top of the cross, with holes threaded to accept a series of standard locking bolts. In the case of machine vise bases, two similarly-shaped slots are machined into the upper surface of the base in a cross shape, or, in the case of a structural units, a single slot is cut into one side of each member.

These slots are open so that, when the T-slot nut slides along them, a bolt can be passed through the slot and into the nut. When the nut is in the correct position, the bolt is tensioned, locking the nut, and whatever device to which the bolt is attached, firmly in place. This sliding movement allows the vice to be moved around the base as required or different sizes and designs of vises to be mounted. Structural cross members can also be moved up and down slotted uprights and locked into the appropriate position using the T-slot nut in the same way.

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