Aluminium extrusion has become the default skeleton for CNC routers, 3D printers, laser cutters and engravers — and for good reason. It's rigid, light, dimensionally accurate, and endlessly reconfigurable. If you're building or upgrading a machine, here's how to choose the right profile and what you'll need around it.
Why aluminium extrusion suits machine builds
A good machine frame needs to be stiff (so cutting forces and motion don't flex it), accurate (so your axes stay square), and adjustable (because every build evolves). Aluminium T-slot / V-slot extrusion delivers all three:
- Stiffness-to-weight — aluminium gives you a rigid frame without the mass of steel, and the profiles are designed to resist bending.
- Built-in fastening — the T-slots let you bolt parts anywhere along the length, so brackets, motors, rails and electronics mount exactly where you need them.
- Built-in motion — the same slots, chamfered for V-wheels, become linear rails for your moving axes (more on T-slot vs V-slot in our separate guide).
- Reconfigurable — undo a few bolts and move things. Prototypes become production machines without starting over.
Choosing your profile size
3D printers and small machines → 20 Series (20 × 20 mm). Light, compact and stiff enough for printer-scale loads. Most desktop 3D-printer frames and small plotters are built from 20 Series. Our 20 Series is built solid, so it's noticeably stiffer than a lot of imported 20 × 20.
CNC routers and heavier machines → 40 Series (40 × 40 mm and up). Routing forces are higher and you want minimal deflection, so step up to 40 Series for the main frame. For long spans — a gantry beam or a wide bed rail — go to 40 × 80 or even 80 × 80 to keep flex down.
A common, sensible pattern: a 40 Series frame with 20 Series for lighter sub-assemblies or where space is tight.
The machine bed
The work surface is where extrusion really earns its place. Our aluminium T-slot machine bed is a 20 × 40 mm tooling plate with T-slots for fast, repositionable work holding — clamp, locate and fixture your workpiece anywhere on the bed. It comes solid or grooved, and the mill finish means you can skim the top flat once it's mounted for a true reference surface.
Don't guess at deflection — calculate it
The one mistake worth avoiding is under-sizing a span and ending up with a frame that flexes under load. Rather than guess, use our deflection calculator (linked on the product pages): enter your span and load and it tells you how a given profile will perform, so you can size up before you cut metal.
What you'll need around the extrusion
A working machine frame is the extrusion plus the hardware that joins and finishes it:
- Corner brackets — square, heavy-duty or concealed — for rigid 90° joints.
- T-nuts, T-bolts and nut plates — for fastening parts anywhere along the slots.
- Cube and 3-way connectors — for strong multi-axis corners.
- V-wheels (Openbuilds-style) — for any axis that needs to move.
- End caps and feet — to finish and stand the frame.
All of it is in our 20 and 40 Series collections, sized to match the profile.
Cut to length, made in NZ
Every profile is extruded by us in New Zealand and cut to your exact length — so you can order frame members at finished size instead of buying full bars and cutting them down. Mill, anodised or powder-coated, no minimum order on stocked lines.
Building a machine and not sure what to spec? Get in touch — we make these profiles ourselves and we're glad to help you size the frame.