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On a 14mm, 12 -point socket with a 17.5mm outside diameter, where is the socket wall the thinnest, and how thin is it? @CarBot

Tom wrote: On a 14mm, 12 -point socket with a 17.5mm outside diameter, where is the socket wall the thinnest, and how thin is it?

On a 14 mm 12-point socket, the thinnest wall is at the “valleys” between the outside flats, lined up with the points of the 12-point broach on the inside. That’s where you have the least metal between the inside corner of the 12-point and the outside surface.

With a 17.5 mm outside diameter, the outside radius is 8.75 mm. A 14 mm across-flats hex has an inscribed radius of 7.0 mm, so if it were a simple 6-point with no corner relief you’d have 8.75 − 7.0 = 1.75 mm radial wall thickness at the flats.

But a 12-point has deeper internal “corners” (effectively closer to the circumscribed radius of the hex), so the minimum wall is closer to 8.75 − 8.083 = about 0.67 mm radial at those internal points, assuming a sharp broach. In the real world it’ll be a bit thicker because the broach corners have a radius, but the thinnest spot is still those valley areas and it’s on the order of roughly 0.7 mm radial (about 1.3–1.4 mm if you’re thinking “total wall” straight across a diameter at that spot).

Impressive answer. This guy is smart! (Or at least that's how it appears to me! )

blueline wrote: Sun Feb 22, 2026 10:22 am Impressive answer. This guy is smart! (Or at least that's how it appears to me! )

It was actually a question to help tune the back end, but a useful one in light of the GT4 spark plug socket post I made earlier. The question/answer helped improve the tune a bit -- helping to tone down the 'confidently wrong' answers. But the grand plan for this tool should neutralize that entirely -- will just take time.