Hanno Braun

Aluminium extrusion ("aluminum", for our North American friends), also called T-slot framing or aluminium profile, is an extremely useful component for building projects in the home shop, especially in combination with 3D-printed parts.

I haven't had a chance to use it for any projects so far, but I'm very interested. I've started to look into it, and this note is a snapshot of the current state of my research. I intend to update it, as I learn more.

Please note that I'm located in Germany, and the following is based on what is available to me locally. I don't know what the situation is like in the rest of the world. For all I know, the information presented here could be universally applicable, or not at all relevant outside of central Europe.

Why Aluminium Extrusion?

Many different types of aluminium extrusion exist, for many different purposes. I'm specifically talking about the kind of extrusion that has T-slots on all (or in some cases some) of its sides, making it a modular building material that can be connected in very flexible ways.

This type of extrusion is extremely attractive for prototyping projects. It can lend strength to your construction, with little requirement for drilling holes or other kinds of machining. You can even buy them pre-cut to specific lengths, meaning you won't need the capability to accurately machine metal at all.

Aluminium is also not the worst material from an environmental perspective, despite high energy use (among other problems) in its production process, as it is so readily recyclable.

Types of Aluminium Extrusion

I-Type and B-Type

There are many different variations of aluminium extrusion out there, but based on what I can find in online stores, two systems seem to be most common: One from Bosch/Rexroth, commonly called "B-Typ" ("Typ" is German for "type", unsurprisingly). The other from item, commonly called "I-Typ". It seems that both systems have become de-facto standards, produced and sold by many different companies.

I wasn't able to find any good comparisons between the two online, nor any guides about when to use one over the other. Based on common sense and specifications found in online shops, I was able to make out the following differences:

• I-Type is slightly more beefy compared to B-Type, meaning I-Type profiles have more mass than B-Type profiles with the same outside dimensions.
• Accessories for I-Type (like nuts that go into the slots) are smaller compared to B-Type accessories for the same size profile. The center holes at the ends of a profile are designed to take a smaller thread for I-Type than for B-Type.
• I-Type is slightly stronger than B-Type, which makes sense given its higher density. I suppose that connections between I-Type beams must be weaker though, given that smaller fasteners are used.
• I-Type seem to be slightly more expensive than B-Type, while I-Type accessories seem to be slightly cheaper than B-Type accessories. Both of which are no surprise, given the size/mass differences.

Overall, there hardly seems to be a difference, as far as I can tell. I'll probably go with I-Type, as it looks more aesthetically pleasing to me.

MakerBeam

The smallest profile size for I-Type and B-Type seems to be 20x20 (mm). If you need something smaller, MakerBeam fills that gap, offering 15x15 (mm) and 10x10 (mm) profiles.

Where to Buy

I haven't bought any aluminium extrusion yet (as of this writing), so I can't give a clear recommendation. None the less, here's where I intend to start.

Motedis looks like a good source for I-Type and B-Type profiles. They have a presence in many countries, a good selection, seem pretty cheap, and offer services like cutting profiles to length and cutting threads into the center holes. This is very useful, if you don't have the capability to do these things yourself with accuracy.

MakerBeam is available on makerbeam.com. They seem to ship from the Netherlands, but also provide a list of resellers.

Conclusion

T-slot aluminium extrusion is an affordable, flexible, and widely available material, as evidenced (not only) by its widespread use in the maker community. I can't wait to get into the fray and use it for one of my own projects.

Meanwhile, I hope these notes from my research into it are useful to you in some way.