This adjustable Allen key tool is one small project for a YouTube channel, one giant leap for …

Inventing the Adjustable Allen Key | Toolroom Takeover 2025 – YouTube Watch On Ever wondered why there isn’t an Allen key (or hex key, if you prefer) equivalent to the adjustable wrench or spanner? Turns out it’s actually quite a complex engineering challenge. But this is 2025, so, the solution hasn’t come from a top university engineering lab or a big corporate, but a YouTube competition. According to YouTube channel Chronova Engineering, the adjustable wrench or spanner was patented back in the 1890s. You might have thought an adjustable tool for Allen bolts, the ones with hexagon inserts in their heads, wouldn’t be far behind. The Allen bolt itself wasn’t invented until a decade or so after the adjustable wrench. But as Chronova Engineering says, there’s surely been enough time since to come up with a solution. But apparently not. So, the channel had a go at what’s thought to be the world’s first adjustable Allen key. Chronova Engineering ran through numerous iterations to come up with a workable solution. The first design had six splines or prongs, one for each of the corners of the Allen bolt insert. That suffered from terminal torsional flex. So, a three-spline alternative was
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