Profile Joints – Part 3
This is the third in our series of posts on aluminium profile joints. In this one we focus on the linear joint.
A few months ago, we had a customer who was building a display stand to use at various trade shows around the country. The interesting things about this stand were a) the finished height needed to be changeable, b) it needed to be quickly and easily assembled and dismantled, and, c) it needed to be readily packed up for transport to and from venues.
Complying with c) was easy. Extruded aluminium profiles are readily amenable to being stacked and tied down to a pallet for easy handling and transport.
To make the thing quickly and easily assembled and dismantled (requirement b), we decided to use clamping plates for most of the joints. See this blog entry for more information about using clamping plates.
The reason for the changeable height was that some of the venues for these trade shows don’t have the ceiling clearance for their particular rather tall display stand. So we decided to make the top section in two parts. One of which could be left out of the assembly when ceiling height decreed.
Now, there are a number of methods to join aluminium profiles end to end. On this occasion though, the customer wanted to maintain the clean neat lines of the aluminium extrusion. As a result, we elected to use linear joints in this case.
The linear joint is ideal when the joint is under a compressive axial load, as was the case here. This joint type is not recommended for high bending load applications such as the middle of a long span beam.
As you can see in the diagram above, the joint piece(s) fit neatly inside the t-slot in the extrusion and there are no parts extending beyond the perimeter of the profile. This diagram shows a 90mm version in the slot 8 series 40 x 40 profile. The number of linear joint pieces used in any given joint is limited by the number of t-slots in the extrusions being joined. The number actually used depends more on the strength and rigidity of the joint required. In many cases, only one or two linear joint pieces are used even though there may be four or even six t-slots in the extrusions.
The linear joint is completed by pushing the ends of the extrusions to be joined firmly together, then tightening the grub screws so that their flat ends bare down on the bottom of the t-slot. This holds the joint piece(s) firmly in place and the two extrusions cleanly together.
Linear joints are available in a number of different sizes for the slot 6, slot 8, and slot 10 series of Alusic extruded aluminium profiles. Also, they are available in anodised aluminium, zinc plated steel, and stainless steel.