Key, Lathe Chuck, 8 mm Square

The square shank on this key doesn't slip or round out, which is a huge relief when I’m really cranking down on a stubborn piece. I’d been worried that an 8mm key might feel undersized for a 4-inch chuck, but it’s actually a perfect, snug fit.

Fits both my 3 and 4 inch chucks perfectly, and the 8mm square drive engages without any slop. The knurled grip gives me enough purchase to tighten firmly without slipping. Exactly what I needed for precise jaw adjustments.

Had been worried that an 8mm key might wobble in my older chuck, but this one fits snug and turns smoothly without any play. The square shank is machined cleanly and engages the socket without jamming.