At my school, one of the teachers had fixed a spring to each chuck key, to make it impossible to leave in by mistake - you had to press the key in to open&#x2F;close the chuck, and as soon as you stopped pressing it in the spring would make the key pop out. I&#x27;d have thought such a simple way of improving safety would be pretty standard by now, but I&#x27;ve not seen it since, at least on any of the home tools I&#x27;ve used.