On Monday, April 5, 2021 at 12:06:35 PM UTC-5, micky wrote:
I bought a USB charging jack designed for a car's dashboard, and
designed to fit in the same size hole as a cigarette lighter.

Many versions for sale. This one, no more expensive than the others,
came with a hole saw for 1 1/16", a size I don't have**. The hole saw
has the shank, the center drill bit, an allen wrench, the hole saw
itself, and a spring!!!

A tapered coil spring whose small diameter just fits the bit. Is that a
coincidence? What is the point of the spring? I've used a hole saw
before and didnt' feel a need for a spring. Is it to force out the hole
after it's been cut? Have you seen this before?


https://www.wonkeedonkeetools.co.uk/holesaws/what-are-the-parts-of-a-hole-saw