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T-Slot extruded aluminium profile joints – pawl clamp

Profile Joints – Part 5

Pawl clamp

In this post the focus is on the pawl clamping connector fastener, or ‘pawl clamp’ for short.  This is the fifth in our series of posts on aluminium profile joints.

pawl clamp

Pawl clamping connecting fastener

A joint constructed using a pawl clamp can have the relocatable advantage of a fixing plate, but via a single fixing screw rather than two. This means less stuffing about on those occasions when a joint needs to be moved.

Information about different styles of pawl clamp can be found on pages 2.53 to 2.56 of the Alusic catalogue.

Adaptable

The Alusic catalogue shows a pawl clamp for almost any joint type your application might require. The basic pawl clamp can be used in place of the standard connection to make a simple square joint, whether T or corner.

There are also pawl clamps that can be used to join profile pieces end-to-end, at an angle or straight, as shown in the diagram below.  This type of joint is stronger than the simpler linear joint or angular joint.  As a result, it can be used to construct a joint that can carry a bigger load, in tension, than a linear joint.

pawl clamp

Preparing the joint

Preparing the joint simply involves machining a hole of the correct diameter and depth in the first of the profiles to be joined. Exact dimensions for the holes to suit each pawl clamp are shown in the Alusic catalogue. The number of holes is determined by the number of pawl clamps the joint needs (2 in this example).

pawl clamp

Ready for assembly

pawl clamp

Joint partly assembled

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Assembling the joint

We can use two pawl clamps to join an 18.5×90 (084.101.006) to almost any profile with an 8mm t-slot. In this example we show it joined to an 18.5×32 (084.101.003), a 1 slot 40×40 (084.102.006), and a 6 slot 45×90 (084.101.019).

Start by putting the pawl(s) into the hole(s) machined in the first of the profiles to be joined.

The joint is completed simply by sliding the pawl clamp square nuts into the t-slot of the second of the profiles to be joined. When the required joint location is reached, simply use a hex key to tighten the fixing screws in place.

pawl clamp

18.5×90 joined to 18.5×32

pawl clamp

18.5×90 joined to 40×40

pawl clamp

18.5×90 joined to 45×90

 

 

 

 

 

 

 

 

 

So there you have it.  The pawl clamp; used to construct strong joints in extruded aluminium profiles, can be adapted to a variety of different joining requirements. The pawl clamp is so adaptable that it could readily be used in applications outside the realm of aluminium extrusions.  Use your imagination, almost any joint requirement can be fulfilled using pawl clamps.

If you want a copy of the Alusic catalogue to peruse on your PC, go to our site main page.  There is a place where you can enter your email address and click the Send button. We will then send you an email with a download link for the PDF file.

 

T-Slot extruded aluminium profile joints – angular joint

Profile Joints – Part 4

Angular joint

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.

angular joint

Angular joint – 45°

 

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.

variable angle joint

Central swivel joint – variable angle

 

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.

angular joint

Angular joint without mitre cuts

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.

angular joint

Angular joint ready for assembly

 

 

 

 

 

 

 

 

 

 

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.

angular joint

Angular joint partly assembled

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.

angular joint

Angular joint completed

 

 

 

 

 

 

 

 

Once the grub screws are properly tightened, you should have a rather tidy nice rigid joint.

 

 

 

If you want a copy of the Alusic catalogue to view on your PC, go to our site main page, fill in your name and email address and click the Send button. We will then send you an email with a download link for the PDF file.

 

T-Slot extruded aluminium profile joints – Linear joints

Profile Joints – Part 3

Linear joint.

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.

T-Slot extruded aluminium profile joints – Linear joints - aluminium extrusion

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.

 

 

Joint construction.

T-Slot extruded aluminium profile joints – Linear joints - aluminium extrusion

Linear joint ready for assembly

T-Slot extruded aluminium profile joints – Linear joints - aluminium extrusion

Linear joint partly assembled

T-Slot extruded aluminium profile joints – Linear joints - aluminium extrusion

Linear joint completed

 

 

 

 

 

 

 

 

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.

 

T-Slot extruded aluminium profile joints – Linear joints - aluminium extrusion

Linear joint – 90mm & 180mm

 

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.

 

If you want your own copy of the Alusic catalogue, go to our site main page, fill in your name and email address and click the Send button.  We will then send you an email with a download link for the PDF file.

 

T-Slot extruded aluminium profile joints – Stronger connection

Profile Joints – Part 2

As a person who is regularly building all manner of things using T slot aluminium extrusions, I occasionally come across a situation where a simple joint using a fixing screw just isn’t going to cut it.  Today I am going to introduce you to just a few of the many different methods of joining T slot aluminium profiles using items found in the Fixing Accessories section of the Alusic catalogue.

Late last year I was putting together a batch of custom designed workbenches when the owner announced that they wanted an LED light panel mounted about 1200mm above the main work surface of each workbench.  No problem, I thought.  Just add a pair of upright sections at the back of each workbench, build a frame to hold each panel and attach to the uprights.

That was all fine until it was let slip that some of the workbenches were to be indirectly attached to pieces of equipment that would put some not insignificant vibrations into the workbenches a number of times per day.  I quickly realised that the simple jointed cantilever design I’d thought of would likely not cope with the dynamic loads generated by oscillations, caused by vibrating machinery, of the panel and frame on the uprights.  Even though that simple jointed cantilever design would be fine with the panel as a static load.

So, a quick design review later.  It was decided to use fixing angles (084.305.033) for the main joints and make braces for the uprights using some joint angles (084.305.011).

fixing angle 43 x 86  joint angle for 40 x 40 profile

 

The fixing angles made the joints very much stronger than they would have been otherwise.  Using joint angles to make braces for the uprights stiffened the structure enough to almost eliminate oscillations that would be generated by the vibrating machinery.  Thinking about it now, just the braces may have been adequate to keep oscillations, and hence joint loads, down enough for the original simple joint design to cope.  Oh well … I think there is a saying in the engineering world that has something to do with “belts and braces”.

A few months after that, the same owner said they wanted some more workbenches (different design of course) also with the LED light panels.  This time though, they wanted to be able to adjust the braces up or down a little for operator head clearance.

At first that seemed a bit complex, not to mention costly.  A stock of different length braces to be removed and replaced by maintenance people as and when required.  I could see there would be no way to guarantee that adequate length braces would not all soon be replaced by the shortest braces, or even removed completely.  Not a viable option in my view.

Then the Alusic catalogue came to the rescue.  Instead of using a joint angle at the end of each brace and making different size braces it was decided to use a screw swivel joint (084.311.010) at the end of each brace.  That would ensure every LED panel support would be adequately braced as well as have a small amount of adjustment using just a hex key.

brace using screw swivel joints

To get your own PDF of the Alusic catalogue, fill in your name and email address on our site main page https://gapengineering.com.au/ and we will send an email with the download link.

 

 

 

 

 

 

 

 

 

T-Slot extruded aluminium profile joints – Standard connection

Standard Connection

The standard connection is the simplest and most cost effective joint for Alusic aluminium T slot profiles.  It is a perpendicular (or square) joint using a single socket head screw (fixing screw) without the use of any fancy accessories.

In this simple joint the hole in the middle of the first profile piece to be joined is tapped with a thread to suit the fixing screw to be used.  The second profile piece has a hole drilled perpendicularly through at the desired location of the joint.  The hole is to allow a hex key to be used to tighten the fixing screw.

T-Slot extruded aluminium profile joints - Standard connection - aluminium extrusion

Details of how to make one of these joints are at this blog post.

Since this joint type is the simplest and most cost effective, it is by far the most commonly used in light, medium, and some heavy duty applications.  For more heavy duty and not so simple applications, other solutions are available.

The standard connection joint type is not limited to use with square profiles either.  It can be used to join rectangular profiles to square profiles as well as rectangular profiles to rectangular profiles.

Probably the only drawback of this simple joint is that it is not readily re-located along the second profile piece should the need arise.  Another hole needs to be drilled to suit the hex key at the desired new location.  Admittedly, this situation doesn’t often crop up, but it does occasionally.  For details of one of many alternative solutions, see this blog post; what are clamping plates.

Full Body Joint

One variation of the standard connection is known as a full body joint.  A full body joint can be used where slightly heavier duty demands.  The main difference in this joint variation is that the drilled perpendicular hole is to suit the fixing screw rather than the hex key.  This adds a small amount of complexity, and hence time, to preparing the joint, but it remains a very cost effective joint.

T-Slot extruded aluminium profile joints - Standard connection - aluminium extrusion                            T-Slot extruded aluminium profile joints - Standard connection - aluminium extrusion

Diagrams from the Alusic catalogue showing two forms of a full body joint.

Joining the other size aluminium profiles

This basic type of T slot connection is not only cost effective it is also incredibly versatile. All of our profiles can be connected this way without the use of any accessories and different size profiles can be joined in this way.