So you want to build a frame?

You've measured twice, maybe even thrice, and now it's time to get building! Frames benefit from precise dimensions. Aluminium profiles provide a great benefit here, because you only have to worry about one: cutting it to length. A 4040 profile for example, is already perfectly sized to 40x40mm! So you have all your lengths cut, let's get assembling!

Sometimes even measuring twice isn't enough. Don't worry, there are so many ways to get to the same result!

Right-angle connections: So many choices, which one suits you?

One of the first things you run into when designing with aluminium extrusion profiles is the right-angle connection. You are probably overwhelmed by the dozens of possible (and correct!) ways to create a connection. Don't worry, it basically comes down to four questions: Do you want to drill into your profiles or not? Do you ever need to reposition things? How much load will the joint carry? And how much do you want to spend?

Let's focus on the most common types for now:

Automatic Fastener

Universal Fastener

Standard Fastener

Angle Bracket

Internal Connector

The Automatic fastener - All-round Champion

This is the go-to connector when speed matters. No machining, no drilling, just screw in the bushing, and tighten the bolt. It's repositionable, meaning you can take it apart and put it back together somewhere else without any damage to the profile. Does a great job at handling loads and forces too!

The trade-off is cost. It's not the cheapest option on the shelf, but you save that cost in assembly time and flexibility. Also, it's less "bulky" than a bracket, that sometimes can also block other items. For prototypes, modular builds, or anything you expect to modify later, it's hard to beat.

The Universal fastener - Great looks will require some work

The Universal sits between automatic and standard. It's still repositionable and delivers the same excellent strength ratings, but it does require machining — a stepped bore per connection. Quite a chunky one too at 20 mm, so be sure to have a drill press or very steady hands.

The benefit over automatic is that it creates a more rigid, screw-based connection. If you're building something more permanent but still want the option to disassemble it cleanly, Universal is a solid choice.

The Standard fastener - It's alright I guess

The Standard is the budget connector. One bore or threaded bore in the profile, and you're done. It's cost-effective and delivers excellent displacement force, though torsional and bending moment performance steps down slightly compared to automatic and universal.

The classic trade-off in this case is: it's not repositionable. Once you've drilled and assembled, that's your connection. So if your design is final and you're building something you don't plan to touch again, Standard makes complete sense. If you want to reposition however, you have to drill again, and you leave quite some holes in your work. Not a great look.

The Angle Bracket - Chunky and not afraid to show it

The Angle Bracket is the most visible of the four — it sits on the outside of the corner. No machining required, can be retrofitted to existing constructions, and it delivers excellent scores across displacement force, torsion, and bending. It also works across a wide range of profile series (5, 6, 8, and 12).

Where it loses points is aesthetics and price. It's an external connector, so it adds visual bulk to the frame. But for utility builds, workbenches, machine guards, or anything where looks aren't the priority, it's fast, strong, and accessible.

The Internal Angle - Sleek but Scrawny

This one flies under the radar, but it might be the cleanest solution of the four. Instead of sitting on the outside of the corner like an angle bracket, the internal angle connector slots directly into the groove of the profile. No machining, no drilling — just insert it, and tighten the two grub screws, simple as.

The result is a completely hidden connection from the outside. Looks great, easy to install and no machining required? Does it get any better? Of course not! The trade-off here is: strength! Your entire structure holds on to those two grub screws. Great for aesthetic or low-load applications, but don't build your frame with them!

How do they actually compare?

Here's a quick overview. Repositionable is only yes if no re-machining like drilling is required.

So, which one?

There's no single correct answer, is what complicated people say. Of course there is! It's the automatic fastener! The only downside is the price, but at Verschraubt we keep that low, so that you are empowered in your projects and keep everything within budget!

The more complicated answer:

• Building a prototype or anything you'll iterate on? Automatic fastening set.
• Permanent build, strong connection, okay with drilling? Universal or Standard.
• On a budget and the design is locked in? Standard or Angle Bracket.
• Need to retrofit a connection to an existing frame? Angle Bracket.
• Need a clean look where strength isn't a requirement? Internal Angle.

The connector choice is part of the design process, but don't spend too much time on it. All of them fulfil the primary purpose of enabling quick connections for building. After 1 or 2 builds, you'll quickly understand the finer details, and what suits you best.

Now let's start building and share your creation!