A spider fitting is the node that connects several point-fixed glass panels to the supporting structure. It is one of the shortest tolerance chains in a facade: the glass hole positions, the spider arm geometry, the ferrule and the structural bracket all have to agree.
A spider cannot be selected from a picture of its arm count. The layout drawing must define the glass grid, the hole pattern, the joint width, the articulation and the interface to the structure.
What is a spider fitting?
A spider fitting, also called a spider bracket, is a cast or fabricated stainless steel component with two, three, four or more arms. Each arm connects to a glass panel through a point fixing, often a countersunk bolt, ferrule and washer. The central body connects to a structural support.
The system may be:
- fixed or articulated at the arms;
- rigid or sliding at the central support;
- surface-mounted or recessed;
- supplied with different arm lengths and angles.
Each variant changes the installation and the glass hole geometry.
What must the layout drawing define?
| Drawing item | Why it matters |
|---|---|
| Glass grid and panel sizes | Sets the arm length and joint positions |
| Glass hole positions | Must match the spider arm centres |
| Hole diameter and countersink | Must match the point fixing |
| Joint width | Determines movement and sealing |
| Spider arm count and angle | Must suit the node, not just the panel count |
| Articulation or fixed connection | Controls how movement is accommodated |
| Support bracket interface | Connects the spider to the structure |
| Material and finish | Defines corrosion resistance and appearance |
| Setting tolerance | Allows the glass to be installed without forcing |
The drawing should locate each hole from the glass edge and from the other holes. A nominally symmetrical panel can still have a hole pattern that only fits one orientation.
Why is the glass hole so important?
Point-fixed glass is not a generic panel with a hole added. The hole is part of the engineered fixing. Its diameter, countersink angle, edge distance and surface condition must match the point fixing and the glass specification. The glass supplier and the facade engineer define the hole; the metal fabricator should not change it to suit a standard spider.
If the spider is articulated, the arm may need to align with the hole through a ferrule or spherical seat. If the glass is laminated, the hole detail must also respect the interlayer and the glass build-up.
What should an RFQ include?
Send:
- Facade layout and glass panel schedule.
- Spider mark and arm configuration.
- Glass hole layout, diameter and countersink detail.
- Point-fixing component detail.
- Required articulation and adjustment.
- Support bracket and structural interface.
- Stainless grade and surface finish.
- Joint and sealant details that affect the node.
- Quantity by mark and packing.
- Sample, inspection and document requirements.
Common mistakes
- Choosing the spider before the glass hole pattern. The hole detail is part of the system.
- Assuming arm count equals panel count. A four-arm spider may not suit every four-panel node.
- Ignoring articulation. A rigid fitting may not accommodate the movement the facade requires.
- Forgetting the support bracket. The spider is only one link in the load path.
- Mixing left and right arm orientations. Similar fittings can be handed.
- Using a generic finish description. The exposure and project specification decide the grade and finish.
Tangtie's spider fitting scope
Tangtie supplies spider fittings for point-fixed glass facade packages. We can produce to the approved arm, hole and interface drawing. Structural design, glass engineering and project approval remain with the facade engineer.
Next step: send the glass layout, spider mark and support bracket drawing together. The quotation can then be based on the actual node geometry rather than an arm count alone.
This note is general technical guidance prepared for the product library. It is not a project-specific approval and does not replace the specification issued by the project engineer. Values requiring test evidence are not published.
