Rosette (node disc)
The steel disc welded to a modular standard every 0.50 m; ledgers, diagonals and brackets wedge into it, up to eight parts at one node.
Also called: perforated disc, node disc, ring, connection disc, rosette disc
Understanding a modular scaffold starts with the rosette. It is the flat steel disc welded onto every standard at 0.50 m intervals, and literally everything hangs on it: ledgers, diagonals, brackets, guard rails. Depending on the manufacturer it is called a rosette or a perforated disc – the principle is the same.
The disc makes forces from every direction enter the standard centrally. That keeps the node stiff and the scaffold predictable. Without it every connection would need a coupler, with more weight, more bolting and more room for error.
Holes, shapes and material
Most discs have eight openings around the circumference, four small and tight, four larger and elongated.
- Small holes fix the right angle. Ledgers hooked in here automatically produce a square bay without measuring.
- Large holes allow connections at other angles – mainly diagonals, and ledgers on round or irregular layouts.
- Shapes: round, octagonal or flower-shaped, depending on the system. The function is comparable, but the parts are not interchangeable.
- Material: steel, galvanised together with the standard.
Up to eight components can meet at one node: longitudinal ledger, transverse ledger, diagonal and bracket all at the same point, with no extra couplers.
Making the connection
- Slide the wedge head of the ledger or brace sideways over the disc so it grips it top and bottom.
- Push the wedge down through the matching hole – small for square bays, large for diagonals.
- Align the bay while the wedges are still loose.
- Drive the wedges home – a 500 g steel hammer is right – until the blow clearly rebounds; only then does the joint carry load properly.
- Before handover, tap each wedge once more. A wedge that still gives was never tight.
For dismantling, the wedges are knocked out from below. Make sure you are not releasing a load-bearing diagonal that is still needed.
What to check, also when buying used
- Never press wedges in by hand only; from a distance a loose wedge looks just like a tight one.
- No heavy sledgehammer – it deforms both disc and wedge head.
- A disc bent slightly downwards usually points to overload or a fall.
- Cracks in the weld between disc and tube rule the standard out.
- Holes must be clear. Concrete, paint or thick zinc drips stop the wedge seating.
- When buying, test a few standards with a matching ledger: the wedge should go in cleanly and sit without play once driven.
Rosette or perforated disc – which is better? Both work. Differences lie in hole shape, available angles and weight. What matters more is staying with one system within a scaffold and keeping the parts in good condition. Used ring systems are listed under modular scaffolding.