T-Slot Nut for Aluminium Profile — Series 20, 30, 40

Dimensions and technical data

The dimensions match the letters in the drawing. All sizes in millimetres.

Data provided by the manufacturer. For a tight fit, confirm with a sample first.

The T-slot nut 20mm is a small fastening part made for 20mm aluminium extrusion profile, the structural bar used to build CNC machine frames, enclosures and workshop fixtures. It slides into the profile’s internal channel and locks in place once a screw is tightened, giving a movable anchor point anywhere along the slot.

It suits machine builders, CNC hobbyists and small workshops assembling frames, guards or motor mounts from T-slot profile. Because the nut can be repositioned before final tightening, brackets and fixtures can be adjusted without drilling new holes or welding. This makes it useful whenever a design changes mid-build and holes already drilled would be the wrong fix.

Features of the T-slot nut 20mm

The nut’s body matches the shape of the internal channel, so it cannot rotate once inserted and tightened. A threaded centre bore accepts a socket head screw, letting two profile sections be joined or a bracket clamped directly onto the extrusion.

Because the T-slot nut 20mm drops into the channel and rotates a quarter turn to seat, no disassembly of the profile is needed to add a fixing point later in a build.

• Sized for 20mm series aluminium profile
• Slides in without removing end caps
• Threaded bore for M5 socket screws
• Anti-rotation body prevents spinning
• Repositionable anywhere along the slot
• Zinc-plated steel for corrosion resistance

Where it’s used

The T-slot nut 20mm is one of the most common fixings in CNC gantry frames, joining cross beams, mounting rail brackets and securing motor plates to 20mm uprights. It also appears in machine guarding, camera rigs and workbenches built from aluminium T-slot profile hardware.

Outside CNC builds, the same nut fixes acrylic panels to a frame, holds cable trays along a base, or anchors brackets that need to slide to a new position later. Anywhere a 20mm profile frame needs an adjustable point, this is the usual fixing.

What to check before buying

Profile slot width varies between manufacturers even within the “20 series” naming, so measure the actual channel opening before ordering rather than assuming compatibility from the profile name alone. An oversized nut will not slide in; an undersized one will rock and fail to grip the channel walls.

Check the screw thread size needed, since the T-slot nut 20mm is commonly tapped for M5 but some assemblies use M4 or M6. Also confirm whether the build needs a drop-in nut fitted through the profile end, or a slide-in type for open-channel access, as the two are not always interchangeable.

Installation and maintenance

To install, insert the nut into the open end of the channel, or drop it through the slot opening, then slide it to position and turn it a quarter turn so the body seats against the internal walls — the same T-slot principle used on machine tool tables, as described on Wikipedia. Tighten the screw until the bracket is fully clamped.

Repeated loosening and retightening wears the threads, so replace a nut once the screw stops holding torque. Keep spares of the T-slot nut 20mm on hand for larger builds, since a single CNC frame can use several dozen, and avoid overtightening past the screw’s rated torque to prevent stripping the profile.

FAQ

Does the T-slot nut 20mm fit every 20mm profile brand? Not always — slot width differs slightly between manufacturers, so check the channel dimension before ordering rather than trusting the “20mm” label alone.

What screw size does it use? Most versions are tapped for an M5 socket head screw, though the exact thread should be confirmed against the part before assembly.

Can the nut be repositioned after installation? Yes — loosen the screw first, then slide the nut to the new point along the slot and retighten; no need to remove the profile or end caps.