Profile Joints – Part 4
In this post we focus on the angular joint; what it is and how to put one together. This is the fourth in our series of posts on aluminium profile joints.
Essentially, the angular joint is a variation of the linear joint. See our earlier blog post on linear joints. While the linear joint could be said to have an angle of 0°, angular joints are available in 30°, 45°, 60°, and 90° fixed versions. The Alusic catalogue has technical details of those angular joints on pages 2.48 through to 2.64 inclusive.
If those fixed angles aren’t enough for you, Alusic also has variable angle joint solutions in the catalogue. They can be found on pages 2.71 and 2.72.
Cutting the extrusion
One of the obvious issues with joints that are not linear or square, is that without both profile pieces mitre cut to the correct angle, the joint will look a bit ugly.
Fortunately these days, reasonable quality mitre saws are relatively inexpensive and easy to get. The only trick is getting a good quality blade and cutting lubricant.
To get a good tight joint you need really good clean cuts. A hacksaw just isn’t going to be good enough, no matter how good your skills. Even a powered hacksaw or band saw isn’t going to give you a great finish.
We use a 400mm diameter tungsten carbide tipped blade in a drop saw designed for cutting aluminium. It can be used to cut extrusions off at almost any angle and produces very nice clean cuts. We offer a modestly priced cutting service for any customer needing their extrusions cut to length.
Preparing a joint
As mentioned above, the key to getting a good tight joint is cutting the extrusion cleanly and at the correct angle. The correct angle usually being half the nominal angle of the joint. In this example, the nominal angle of the joint is 45° so we have mitre cut the pieces to be joined at 22.5°. This joint type usually requires two angular joints to ensure sufficient joint strength and balanced load carrying ability.
Putting it together
As you can see in the first diagram above, the angular joints fit neatly inside the t-slot in the extrusion. One of the advantages of this joint type is that there are no parts extending beyond the perimeter of the profile.
The first step is to slide the angular joints into the t-slots of one of the profile pieces and screw down the grub screws to take up all the play in the slot. Do not properly tighten the grub screws just yet. Simply nipping up only one of the grub screws at this stage is enough.
The joint is completed by pushing the ends of the profile pieces firmly together then tightening the grub screws so that the grub screw flat ends bear down on the bottom of the t-slot. This effectively clamps the angular joint into the t-slot of the extruded profile. Before properly tightening the grub screws make sure the ends of the profile pieces are nicely aligned.
Once the grub screws are properly tightened, you should have a rather tidy nice rigid joint.
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