Gary inquires about the rationale for solid center augers.

My (possibly incorrect/incomplete) understanding is that solid center augers are
supposed to be less likely to flex when drilling very long/deep holes.
Therefore, I infer that they may also be able to handle more torque than a twist
auger bit might (as when driven by a power drill). As far as how they are made I
have no knowledge, but they look like they could be either milled from solid bar
or forged/swaged.

On a related note, another galoot asked me off-list whether the company that had
the auger factory in the video I mentioned the other day was still in business.
Apparently it is not. The company was Clico, of Sheffield, and it looks like it
went out of business almost exactly three years ago.   :-(

John