Special joints
Not every joint is a corner. Where two members cross at the same level, where a butt joint has to be hidden, or where a member ends inside another, the standard bracket range runs out. This is the family that covers those cases: cubic connectors, linear and bar connectors, end connectors and inner brackets.
23 items
Other connecting elements are the joints the standard corner-bracket range does not cover: cross joints where two members intersect at the same level, butt joints that have to be joined invisibly, and end connections where one member terminates inside another. The common parts are cubic connectors, linear or bar connectors, end connectors and inner brackets.
Below: which part suits which joint, and why the joint you cannot find hardware for is usually the joint that should be redesigned.
| Joint | Problem | Usual part |
|---|---|---|
| Cross at the same level | Two members intersect; neither can pass through the other | Cubic connector, or a corner bracket pair on a cube |
| Hidden butt joint | Two members in line, with nothing visible on the outside faces | Linear bar connector or an internal butt connector |
| End into a through member | A member ends against the side of another, at any angle | End connector or an anchor connector variant |
| Screw connection | A joint that must be made without any external bracket at all | Screw connector, using a tapped hole in the profile |
| Inner brace | A corner that needs to be braced from inside with nothing on the outer faces | Inner bracket |
A cubic connector is a cube-shaped fitting that sits in the slot of two crossing members and joins them at the same level. It is the standard answer where a cross joint is genuinely required and one member cannot be continuous.
Two practical points. First, a cubic connector is a compact fitting carrying a cross joint, so it is not a high-load part; where a cross joint carries load, one member should be continuous and the other should be terminated against it with a plate. Second, because the cube sits in the slot, it consumes slot length at the intersection, which affects where the neighbouring hardware can go.
A linear or bar connector joins two members end to end with the fixing hidden inside the slot. It is the concealed equivalent of a joining plate, and it exists for the same reason as an anchor connector: a butt joint on a visible face should not show hardware.
| Type | How it fixes | Notes |
|---|---|---|
| Internal bar connector | A bar spans the joint inside the slot, bolted from each side | The usual choice; needs access to the slot on one face |
| Threaded bar connector | A threaded bar with a top thread is screwed into tapped ends | Fully concealed; needs both ends tapped |
| End connector | Fixes into an end face and into the slot of the abutting member | Used where one member terminates inside another |
| Screw connector | Uses a tapped hole drilled directly into the profile core | No bracket at all; the load goes into the extrusion itself |
There is a useful rule in profile framing: if no standard part fits a joint, the joint is usually the problem. Three cases come up repeatedly, and all three have a cheaper standard answer.
Practical point: redesigning a layout to use only corner and tee joints usually removes the need for special connectors entirely, reduces the part count, and produces a stiffer frame. Special connectors are a solution, but they are rarely the best one.
Concealed butt and end connectors share one requirement with concealed corner joints: the fixing has to be reachable. An internal bar connector needs access to the slot on one face; a threaded bar connector needs both ends tapped before assembly. That means the frame has to be planned and the machining done before anything is cut, and it means a concealed joint cannot be added later.
Where access is uncertain, a visible plate or bracket is the safer choice. It is better to accept a visible fixing than to design a frame that cannot be assembled.
Special connectors are generally compact, and compact means the load is concentrated. Three points are worth remembering.
These connectors use the standard fastener family for their series: M6 for the 30 series with an 8 mm slot, M8 for the 40 and 45 series with a 10 mm slot. Bolt length is critical on concealed parts because there is no room for a bolt that bottoms out. Where a connector is supplied as a kit, use the fasteners supplied rather than substituting from stock.
The full hardware range is described under fastening elements, and the standard joint parts under connecting elements.
Describe the joint rather than the part: which members meet, at what angle, whether either member is continuous, whether the outside faces have to stay clean, and whether the frame is already built. From that we can identify the correct part, and tell you if a layout change would remove the need for it. If you have a drawing of the joint, send it — a section view is usually enough. Standard parts are quoted within one working day. Related ranges: connecting elements, anchor connectors, joining plates, angle profile brackets and CNC machining.
FAQ
Cross joints where two aluminium profiles intersect at the same level and neither can pass through the other. They are compact fittings rather than high-load structural joints.
Use a linear bar connector inside the slot, or a threaded bar connector with both ends tapped. Both are concealed equivalents of a joining plate.
Not usually. The joint is always the weak point, so where possible use a single longer extrusion - standard lengths go up to 6 m.
A connector that uses a tapped hole drilled directly into the profile core, so no external bracket is needed. The load goes into the extrusion rather than the slot lip.
Usually because the joint is a cross or a butt that could be redesigned as a corner or a tee, which uses standard parts and is stronger. Redesigning the layout often removes the need for a special connector.
Concealed types do. Internal bar connectors need slot access, threaded bar connectors need tapped ends, and screw connectors need a tapped hole in the profile.
The standard family for the series: M6 for the 30 series with an 8 mm slot, and M8 for the 40 and 45 series with a 10 mm slot.
Generally no, because the concealed types need machining done before assembly. Visible plates and brackets are the retrofit option.
Send the drawing, the section size or a sample and we will confirm the alloy, the tolerance, the finish and the commercial terms. Quotes for standard items normally go out within one working day.
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