Corner brackets
Cast or folded L-brackets with M5 bolts and T-nuts; the most common joint for 2020 frames.
Metric T-slot framing, 20 mm module
2020 & 2040 Aluminium Extrusion
2020 and 2040 are the smallest common metric T-slot profiles: 20 × 20 mm and 20 × 40 mm sections with a 5 mm or 6 mm slot on each face, sized for M4 and M5 fasteners. They are the standard frame material for 3D printers, laser engravers, small CNC routers and benchtop rigs. Metline supplies both in 6063 alloy, cut to length, tapped and anodised clear or black, worldwide.
- Sections
- 20 × 20, 20 × 40, 10 × 20 mm
- Slot
- 5 mm or 6 mm
- Alloy
- 6063-T5 / T6, 6105-T5
- Finish
- Clear or black anodised
What are 2020 and 2040 extrusions?
The numbers are simply the section size in millimetres. A 2020 is a 20 mm square with one slot centred on each face; a 2040 is two 2020 sections side by side, with two slots on each long face and one on each short face. Both are hollow at the core, with a centre bore that can be tapped for an end bolt.
These profiles became the default for desktop machines because they are light, cheap, accurate enough for small linear motion and easy to work with hand tools. Many open-source 3D printer designs use 2020 for the frame and 2040 for the gantry or Z axis, where the deeper section resists bending and twisting from moving print heads.
The most important detail when buying is the slot type. "B-type" 2020 profiles usually have a 6 mm slot and take M5 hardware; "I-type" or 5-series profiles have a narrower 5 mm slot shaped for M4 or M5 nuts. The two look similar, but nuts and brackets for one do not always fit the other. Send a photo or drawing of your current profile, or state the slot width, and we will match it.
Profile types and sizes
| Profile | Section | Slots | Typical use |
|---|---|---|---|
| 2020 | 20 × 20 mm | 4 (one per face) | Frames, enclosures, light supports |
| 2040 | 20 × 40 mm | 6 | Gantries, Z-axis rails, longer beams |
| 2060 / 2080 | 20 × 60 / 20 × 80 mm | 8 / 10 | Wider beams and bed supports |
| 1020 | 10 × 20 mm | Usually 1 – 2 | Panel frames, trim, light guards |
| 2020 variants | 20 × 20 mm | 1 – 3 open slots, closed faces, 90° and 45° corner shapes | Neat edges and corners where slots are not needed |
Linear-rail builds often use 2040 or 2080 as the rail base. For V-wheel carriages, choose a profile with a V-slot form, which is a different shape from a standard T-slot.
Section properties and deflection
2020 and 2040 are produced by many extruders, and wall thickness and slot shape vary, so section data differs from one design to another. The ranges below cover common profiles; ask for the data sheet of the exact profile before final design.
| Property | 2020 (6 mm slot) | 2040 (6 mm slot) |
|---|---|---|
| Weight | About 0.40 – 0.57 kg/m | About 0.75 – 0.95 kg/m |
| Moment of inertia Ix | About 0.7 – 0.9 cm⁴ | About 1.2 cm⁴ (flat) |
| Moment of inertia Iy | Same as Ix | About 4.5 cm⁴ (on edge) |
| Centre bore | Typically 4.2 – 5 mm, tappable to M5 or M6 | Two bores |
Using δ = PL³ / 48EI with E = 69 GPa, a 500 mm 2020 beam with a 100 N load at mid-span deflects about 0.5 mm. The same load on a 2040 standing on edge deflects only about 0.08 mm. That is the main reason printer and router designs use 2040 for moving axes: deflection directly affects print and cut accuracy.
Metric 20 mm profiles are mostly extruded in 6063-T5 or T6, which extrudes cleanly in thin walls and gives a smooth, even anodised surface. 6105-T5 can be quoted where higher strength is needed.
| Alloy and temper | Min. tensile strength | Min. yield strength | Character |
|---|---|---|---|
| 6105-T5 | 262 MPa / 38 ksi | 241 MPa / 35 ksi | Usual North American T-slot alloy: strong, extrudes well, good anodising |
| 6063-T5 | 152 MPa / 22 ksi | 110 MPa / 16 ksi | Lowest cost, best surface; adequate for light frames |
| 6063-T6 | 207 MPa / 30 ksi | 172 MPa / 25 ksi | Common for metric profiles; the 25 ksi yield figure often quoted in catalogues |
| 6061-T6 | 262 MPa / 38 ksi | 241 MPa / 35 ksi | Highest strength of the group; harder to extrude in thin, complex sections |
Minimum values from ASTM B221 for sections up to about 12.7 mm wall; EN 755-2 gives similar figures for EN AW-6063 and EN AW-6005A. Stiffness (E ≈ 69 GPa) is the same for all four alloys, so alloy choice changes strength but not deflection.
Fittings for 20 mm profiles
Joining plates
Flat plates in L, T and cross shapes for flush corner joints, especially on printer frames.
Hidden corner connectors
Internal connectors for clean edges; require a drilled access hole.
T-nuts
Hammer-head and roll-in nuts that can be fitted from the front, plus slide-in nuts for maximum strength.
End caps and slot covers
Finish cut ends and cover unused slots to stop dust and debris collecting.
Panels
Acrylic or composite panels 3 – 4 mm thick fit directly into the slot for small enclosures.
Finishes for 2020 and 2040
Clear anodising
The standard finish: a hard, transparent oxide layer (typically 10 – 15 µm) that resists corrosion and scuffing and keeps a clean satin look.
Black and colour anodising
Black is popular for optical, laser and display equipment because it cuts reflections. Other dyed colours can be quoted for safety or brand colour coding.
Powder coating
A thicker, coloured coating for washdown areas or where a specific RAL colour is required. Slots may need masking so T-nuts still slide freely.
Cut ends and machined faces
Any cut, drilled or tapped surface made after anodising shows bare aluminium. It is cosmetic only, as aluminium forms its own thin oxide film, but specify machining before finishing if appearance matters.
Matching 2020 and 2040 fittings (brackets, gussets, joining plates and T-nuts) can be supplied in the same finish so the assembled frame looks uniform.
Lengths, machining, tolerances and packing
Supply and quality
- Lengths
- Stock lengths up to about 6 m, or cut to length to your list
- Machining
- End tapping (M5 or M6), access holes, drilling and mitring
- Tolerances
- Section and straightness to EN 12020-2 for 6060/6063 precision profiles, or ANSI H35.2
- Squareness of cuts
- Important for printer frames; state any requirement on the order
- Packing
- Each length film- or foam-wrapped; bundles sealed with desiccant for sea freight; ISPM 15 crates
- Labelling
- Size, quantity and batch number on each bundle, or kit labels per part
Small profiles bend and scratch easily in transit. Ask for cartons or crates rather than loose bundles for export orders.
Where 2020 and 2040 are used
- 3D printers: frames, gantries and Z axes for desktop and large-format printers
- Laser engravers and small CNC routers: frames and rails
- Automation fixtures: jigs, sensor mounts, test rigs and small pick-and-place frames
- Electronics enclosures: frames for control boards, wiring and small panels
- Workshop and home use: shelves, tool stands, carts and hobby builds
- Camera and lighting rigs: light, adjustable supports
When to move up from 2020 to 3030 or 4040
| Feature | 2020 | 3030 | 4040 |
|---|---|---|---|
| Slot | 5 – 6 mm | 8 mm (6 mm on some) | 8 – 10 mm |
| Typical bolt | M4 / M5 | M6 | M8 |
| Approx. weight | 0.4 – 0.57 kg/m | 0.8 – 1.1 kg/m | 1.4 – 1.8 kg/m |
| Approx. I (base profile) | 0.7 – 0.9 cm⁴ | 2.5 – 3.5 cm⁴ | 7 – 10 cm⁴ |
| Best for | Desktop machines, light frames | Workbenches, guards, medium frames | Machine frames and heavier structures |
Move up a size when spans exceed about 600 – 800 mm under load, when the frame carries motors or people, or when vibration loosens small M5 joints. See 3030 / 3060 and 4040 / 4080 profiles.
How to order 2020 and 2040 extrusion
- List the profilesProfile size and variant (standard, light, grooved, closed face), finish and colour.
- Give cut lengthsA cut list with quantities, or a drawing of the frame. Note any end taps, counterbores or access holes for connectors.
- Add fittingsBrackets, gussets, T-nuts, feet and covers, with quantities, or ask us to prepare the list from your drawing.
- QuoteWe confirm the 2020 / 2040 profiles, machining, packing and delivery terms (EXW, FOB, CIF or DAP).
- Pack and shipEach length is film-wrapped and packed in cartons, bundles or ISPM 15 compliant crates, labelled by part number for easy assembly.
References and standards
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- EN 12020-2 – Extruded precision profiles in alloys EN AW-6060 and EN AW-6063: tolerances
- ANSI H35.2 – Dimensional Tolerances for Aluminum Mill Products (The Aluminum Association)
- EN 573-3 – Chemical composition and form of wrought products
2020 and 2040 aluminium (aluminum) extrusion: FAQs
What is the slot size of 2020 aluminium extrusion?
Most 2020 profiles have a 6 mm slot (B-type, M5 hardware); 5-series or I-type profiles have a 5 mm slot. Confirm the slot type before buying fittings.
How much does 2020 extrusion weigh?
Typically 0.40 – 0.57 kg per metre, depending on wall thickness and profile design. 2040 weighs about 0.75 – 0.95 kg/m.
Is 2040 the same as two 2020 profiles bolted together?
Not quite. A 2040 extruded as one piece is stiffer and straighter than two 2020s bolted side by side, and it has a continuous centre web.
Which alloy is used for 2020 extrusion?
Usually 6063-T5 or T6. 6105-T5 can be supplied where higher strength is required.
Can 2020 be tapped at the ends?
Yes. The centre bore is usually tapped M5 or M6 for end-bolt joints. We supply profiles cut and tapped to order.
Do 2020 profiles fit 10 series inch fittings?
No. 10 series is a 1-inch system with different slot geometry and inch bolts.
Need 2020 or 2040 profiles?
Send the slot type, cut list, finish and fittings, and we will reply with a complete quotation.
