If you're starting a build with aluminium extrusion — a machine frame, a guard, a CNC or 3D-printer gantry, a workbench — one of the first questions is whether you need T-slot or V-slot profile. They look similar, they're often confused, and plenty of online sellers stock only one. Here's the plain-English difference, when each matters, and why our profiles give you both.
The quick answer
- T-slot is about fastening. The slot is shaped like a "T" so you can drop or roll in nuts and bolts anywhere along the length and bolt components together. It's the standard for framing, brackets and structure.
- V-slot is about motion. The slot edges are chamfered to a "V" so a wheel can run along them, turning the extrusion into a linear rail. It's used where something needs to slide — a carriage, a gantry, a moving axis.
The catch most people hit: a pure T-slot profile won't take V-wheels, and a pure V-slot profile is fiddly to fasten into. So you end up choosing — unless your profile does both.
T-slot in detail
A T-slot profile has a slot opening that's narrower at the face and wider inside, forming a T-shaped channel. That geometry lets you:
- Roll in T-nuts and T-bolts anywhere along the slot — no drilling, no fixed hole positions.
- Bolt on brackets, gussets, gates, panels and feet wherever you need them.
- Reconfigure later — undo the fasteners and move them, because nothing is permanent.
This is the workhorse mode. Machine frames, safety guarding, workstations, conveyor framing and benches are almost always T-slot builds. If your project is structural — things bolt together and stay put — T-slot is what you want.
V-slot in detail
A V-slot profile has the same family of slots, but the edges are chamfered at an angle so the slot doubles as a track. Special wheels with a matching V-groove run along those edges, so the extrusion becomes a linear rail for very little cost.
That makes V-slot the go-to for:
- 3D printers — the print head and bed ride on V-slot rails.
- Small CNC machines, plotters and laser cutters — moving gantries and carriages.
- Sliding doors, drawers and adjustable jigs — anywhere you want smooth, low-cost linear movement.
V-slot is brilliant when something needs to move. On its own, though, it's less convenient for general fastening.
Do you need one, the other, or both?
Most real builds need both behaviours: a structure that bolts together (T-slot) and one or two axes that slide (V-slot). Traditionally that meant buying two different profiles, learning two part systems, and keeping two sets of hardware.
This is where our profile is different.
Our profiles are T-slot and V-slot in one
Every extrusion in our 40 Series and 20 Series systems is built with an 8 mm T-slot on every face, with the slot edges chamfered to suit V-slot (Openbuilds-style) wheels. One profile takes standard T-slot nuts and bolts for framing and V-wheels for motion.
In practice that means:
- You build your frame with the same profile you build your moving axis from.
- You stock one profile and one hardware system instead of two.
- You can change your mind mid-build — add a sliding axis to a frame, or bolt a bracket onto a rail — without buying different material.
It's the flexibility of both systems without the "which one do I order?" headache.
Which size? 20 Series vs 40 Series
Once you've sorted T-slot vs V-slot, the other choice is profile size:
- 20 Series (20 × 20 mm) — light and compact. Ideal for 3D printers, small CNC machines, enclosures, displays and light framing.
- 40 Series (40 × 40 mm and up) — the structural workhorse. Machine frames, safety guarding, gantries, workstations and automation. Larger sections (40 × 80, 80 × 80) handle longer spans and higher loads.
A common pattern is a 40 Series frame with 20 Series used for lighter sub-assemblies or moving parts.
Compatibility and finishes
Our profiles work with standard 8 mm T-slot hardware and Openbuilds-style V-wheels, so they slot into the wider ecosystem rather than locking you into a proprietary system. They're available mill finish, silver anodised, or powder-coated (including high-visibility safety-yellow), and we cut every length to your exact size — no minimum order on stocked lines.
The bottom line
- Choose T-slot behaviour when you're fastening and framing.
- Choose V-slot behaviour when something needs to move.
- Most builds need both — and our profiles give you both in a single extrusion, made in New Zealand and cut to length.
Not sure which profile or size suits your project? Get in touch — we extrude these ourselves and we're happy to help you spec the right one.