Outside and inside corners
Specify both corner radii if a part fits around or inside the section. A nominal width is not enough to check clearance at the corners.
FACTORY-DIRECT / CUSTOM MANUFACTURING
Carbon fibre square & rectangular tubes.
Built around your assembly.
Specify the section, wall and length. Discuss corner details, reinforcement and machining for frames, brackets and equipment.
Custom dimensions · Cutting & drilling · Quoted to your drawing
HOW TO SPECIFY40 × 20 mm outside × 2 mm wall × 1000 mm long
Width A × height B × wall t × length.
Nominal internal flats: 36 × 16 mm; radii specified separately.
Drawing example, not a stock item.
MAKE YOUR REQUIREMENTS CLEAR
Define the section.
Then the connection.
Enter outside width, height and nominal flat-wall thickness. For a square, use equal width and height. The calculated internal dimensions assume uniform walls and exclude corner radii.
These values start a custom enquiry. Dimensions, tolerances, material and production feasibility are confirmed in the quotation.
Ask for material, tooling where needed, machining, samples and delivery costs to be identified separately. Add the delivery country and target quantity for a useful comparison.
WORKSHOP / DIMENSIONS
Square tube sizes: outside, inside & wall.
Reference dimensions for a custom enquiry, not a stock list or a limit on manufacturing capability. Small pultruded profiles and larger multi-directional laminates need different construction specifications. Confirm tooling, radii, tolerances and finished length in your quotation.
Dimensions in millimetres unless shown otherwise. Scroll sideways on a small screen.
| Outside A × B (mm) | Nominal inside (mm) | Flat wall t (mm) | Your enquiry |
|---|---|---|---|
| 4 × 4 | 2.5 × 2.5 | 0.75 | |
| 6 × 6 | 4 × 4 | 1 | |
| 8 × 8 | 7 × 7 | 0.5 | |
| 10 × 10 | 8 × 8 | 1 | |
| 20 × 20 | 17 × 17 | 1.5 | |
| 22 × 22 | 20 × 20 | 1 | |
| 32 × 32 | 30 × 30 | 1 | |
| 42 × 42 | 40 × 40 | 1 |
WORKSHOP / SECTION BASICS
A square is more than four flat sides.
Flat walls and corner build-up
A wall dimension across a flat does not fully describe the corner construction. Ask for the section drawing rather than assuming a perfectly sharp hollow square.
Straightness and twist
Long profiles may need explicit straightness and twist limits. Define a measurement length, datum and method that matches your assembly.
WORKSHOP / CONNECTIONS
Protect the connection, not just the surface.
Pultruded versus moulded
A predominantly axial pultrusion is different from a moulded laminate with multiple reinforcement directions. Do not transfer a strength rating between constructions.
Bolted joints
Discuss how the bolt load enters the wall and whether a sleeve, insert or load-spreading part is needed. A generic tightening torque cannot be assigned from tube size alone.
Machined features
Define hole position from a datum and show edge distances. Check both sides after machining and agree how visible damage or splitting will be assessed.
DRAWING CHECKLIST
Specify the faces that locate your part.
Cut ends & length
Define finished length, cut squareness and any end treatment. State the datum face if the end locates a bracket or insert.
Holes through two walls
Show the hole axis, both wall locations and alignment requirement. A through-bolt may need a sleeve or load-spreading detail to prevent local crushing.
Fits at the corners
Include inside and outside corner radii and the mating part drawing. Flat-to-flat clearance alone does not establish a telescoping fit.
WORKSHOP / QUESTIONS
Before the section becomes a frame.
Can I order larger or rectangular sections?
Send the outside dimensions, wall requirement, length and corner details. We can review the custom process and tooling rather than forcing the design into the small reference profiles shown above.
Will one square tube telescope inside another?
Nominal flat clearance is only one part of the check. Internal corner radii, external corners, twist, straightness and any guide system also control whether the sections move freely.
Is carbon fibre always better than metal here?
The comparison depends on stiffness, mass, joints, environment and cost. Share the current assembly and the improvement you need, rather than assuming a material swap alone will solve the problem.
Take the next step.
Custom parts for specialist equipment.
LET’S MAKE IT CLEAR.
What are
you building?
You don’t need a complete specification to start a conversation. Tell us the application and what you know so far.
sales@fibreparts.com ↗