Testing Various Properties Of LEGO-Compatible Axles

If you ever wondered what’d happen if you were to use LEGO Technic parts, but they were made out of something other than plastic, the [Brick Experiment Channel] has got you covered. Pitting original Lego axles against their (all except steel commercially available) equivalents made out of carbon fiber, aluminium and steel, some of the (destructive) results are very much expected, while some are more surprising.

Lego-compatible axle test results. (Credit: Brick Experiment Channel, YouTube)

Starting off with the torque test, each type of axle is connected with others and rotated with increasing torque until something gives out. Unsurprisingly, the plastic Technic part fails first and renders itself into a twist, before the carbon fiber version gives up. Aluminium is softer than steel, so ultimately the latter wins, but not before a range of upgrades to the (LEGO-based) testing rig, as these much stronger axles require also strong gears and the like to up the torque.

When it comes to durability, all except the original LEGO version didn’t mind having plastic rubbing against them for a while. Yet for friction in general, the plastic version did better, with less friction. Whether or not this is due to material wearing away is a bit of a question. Overall, stainless steel gets you a lot of strength, but in a dense (8000 kg/m3) package, aluminium comes somewhat close, with 2700 kg/m3, and carbon fiber (1500 kg/m3) does better than the original part (1400 kg/m3), with only a bit more weight, though at roughly ten times the cost.

On that note, we’re looking forward to the first 100% stainless steel LEGO Technic kit, reminiscent of the era when Meccano came in the form of all-metal components and a bucket of bolts.

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Hackaday Prize 2023: Universal Tensile Testing Machine

Material testing is important in big industry, where manufacturers must be able to trust the properties of the raw materials they’re using. The rest of us generally take a supplier’s word for it that they’re giving us what we’ve paid for. However, you could always take on material testing yourself with the Universal Tensile Testing Machine from [Xieshi Zhang].

Unlike a six-figure industrial machine, this build is much more affordable, costing on the order of $300 to build. It uses an Arduino to read a tensile strain gauge, and is capable of applying up to a kilonewton of force. To achieve this, it uses a NEMA 17 stepper motor driving a lead screw to apply tensile strain or compression to the specimen under test.  The test fixture is assembled from 3D-printed components, and built on top of a piece of aluminium extrusion.

Fundamentally, it’s a smaller version of a machine most engineering undergraduates will see in a materials lab experiment. It could be highly useful for anyone wanting to experiment with 3D printed structures; it would be more than capable of testing various filaments and infill types for their tensile and compression performance. Video after the break.

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