Building things with metal isn’t as hard as you’d think: V-slot and T-slot aluminum extrusions make it simple to build structural frames. Join me as I talk you through what it is and how you can get started with the stuff to build something amazing.
What Is Aluminum Extrusion?
Aluminum extrusion is aluminum that has been extruded through a funny shaped hole called a die. Similar to how many plastics and food are manufactured, hot metal is squeezed through a shaped hole that produces a useful product. This is a somewhat simplified view, so if you would like to know the finer points of the manufacturing process, have a look here.
This may sound like a lot of effort, however it has many advantages. Extruded aluminum is actually stronger, lighter, and uses less material (meaning it’s cheaper) than its solid counterparts. Extrusions come in a wide variety of shapes, so a variation suitable for your specific use case can often be found. Finally, aluminum is very easy to work with using only basic tools. It’s often not suitable for heavy-duty applications (such as fighting battlebots), however you may be surprised at what can be made with it.
V-Slot vs. T-Slot
There are many different shapes of extrusion available. The shape of the cross section is called the profile. There are two main profiles that are useful to you: T-Slot and V-Slot.
T-Slot has a T-shaped groove on each side:
V-Slot is similar, but it has a slight bevelled edge:
While this may seem like only a minor difference, it has a big impact in their use. V-Slot allows bearings and wheels to sit inside the profile, meaning it can also double as linear rail, greatly reducing the cost of parts for motion control.
The two are somewhat interchangeable, but it’s usually best to stick with one type per project. Basic parts like brackets and T-Nuts work fine on either, however slightly more specialist parts — such as bearings or unusual joints — may only work on one or the other. Also, if you are mixing and matching parts, you may need to change or adapt your design, and have to purchase more lengths of one or the other extrusion.
V-Slot was created by Mark Carew of OpenBuilds and is open source. While there are a few other variations available, this article will focus on V-Slot. OpenBuilds explain their system in this video:
V-Slot comes in a variety of different sizes, and the range is expanding. It comes in various lengths, and some distributors will even cut to length. The most popular sizes are:
- 20mm x 20mm
- 20mm x 40mm
- 20mm x 60mm
- 20mm x 80mm
Even the smallest diameter pieces (20mm x 20mm) are very strong, and the largest pieces are more than capable for heavy-duty purposes.
Cutting and Working
You can cut V-slot in a variety of ways. The manufacturers state that it can be cut just like timber on a chop saw, however I don’t recommend this — it’s quick way to dull your blade, and unless you have a special blade for cutting metal, it may not produce a nice finish either.
The easiest way to cut it (even the larger 20 x 80) is by using a hacksaw (UK). Use an Engineer’s Square (UK) to mark an accurate line, then slowly cut it (once secured to an appropriate work bench). Don’t bother with a junior hacksaw (even for small stuff) as they are often rubbish.
You can purchase V-Slot in two finishes: untreated and black. Untreated is simply the aluminum as is, whereas black has been anodized — a chemical process that reacts with the surface of the metal.
Black looks far cooler, but is much easier to mark or damage. Plain allows you to anodize in a variety of colors at a later date. Paint is not suitable, nor is powder coating, as these both involve a layer of paint outside the part, which reduces the effectiveness of the bearings.
Connecting pieces together is very easy. The most common method is through T Nuts. These slot into the grooves in the aluminum, and allow a bolt to tighten up against them, like this:
They are fairly cheap ($12.99/100), although they can sometimes be fiddly to align multiple ones correctly. Open builds sell various joining brackets for different purposes.
If you want to save a bit of money, you could 3D print your own connectors:
Alternatively, metal brackets from a hardware store can often be purchased very cheaply:
As these come in a variety of sizes, you may wish to write down some measurements to purchase brackets of an acceptable size. Using these brackets is very easy, slide two (or more) T Nuts into the channel in the extrusion:
Next, line up your bracket:
Then bolt it on using the appropriate size bolts:
Use the same method to connect a different piece of extrusion:
Bearings are simply bolted on (providing the spacing is correct):
Although you may want to countersink the bolts:
Where to Buy
The easiest place to purchase from is the OpenBuilds store. It costs $10 for 1M of 20 x 20 up to $20 for 20 x 80. Various connectors, plates, and wheels can be purchased in differing sizes and specifications, as can be seen in this video:
Amazon.com sell parts, as do Aliexpress. While parts may seem cheaper on Aliexpress, the postage can often negate the price, as well as any import duties.
What Can You Make?
It’s entirely possible to produce something using only off the shelf parts. If you want to save a bit of money, you can easily manufacturer your own parts using timber or plastic. Make sure to brush up on your DIY tech skills first.
I designed and 3D printed this camera slider in a weekend:
I designed these parts using Google Sketchup — it’s very easy to use. Make sure you check out the basics. If you still need some inspiration, take a look at these computer workspace upgrades, enhance these IKEA office hacks, or maybe you could build a smart home like in Mr. Robot.
Have you built anything using aluminum extrusion? Let me know in the comments below, I’d love to see!
Image Credits: Peter Sobolev/Shutterstock