Ok: my bit brace is on the way, so it's time to find auger bits.
I think I understand that the critical work is done at the tip of the bit and that the rest of the tool simply conveys the chips out of the hole. It's also clear that one should do as little as possible with the file to avoid spoiling the bit geometry.
I have ordered an auger bit file and located a full set of Russell Jennings bits that are priced cheap but significantly spotted with rust. Are these likely to be salvageable, or should I hold out for some rust-free augers?
You guys are great - thanks.