Augers have long been used for boring holes through ice, but it is difficult to find an ice auger smaller than 6 inches in diameter. There are plenty of smaller augers for wood boring, but they top out at around 1.5 inches. Even so, we plan to use at least one of these.
Wood augers have a screw tip designed to pull the bit into the wood. Unfortunately this doesn't work at all in ice, so I did some experiments today to see if a wood auger could be modified to work in ice.
I started with an old 3/4 inch auger that I picked up at a thrift store. It wasn't completely useless in ice, but I'd rate its performance at only about 40%. Not having an old brace, the first thing I had to do was hack off the square taper shank. Then I ground off the screw tip and what I'll call wings on the outer edge. I'd say that at best it only performed at about 5% in this condition. It was pretty bad.
I decided to compare it to a 6 inch hand cranked ice auger (for fishing) that I picked up on ebay a few months ago. I was worried about the flat center of my modified auger; it seemed that flat section was just pushing in vain against the ice. The 6 inch ice auger has a fairly small gap between cutting blades at the center, so I decided to try to cut a gap in mine.
I cut a groove across the center and tried it again, but I didn't notice any improvement. In hindsight, I think that these first couple of modifications may have resulted in a curvature that cause the cutting edges to not be fully in contact with the ice. I didn't notice that at the time, but I decided to try a more aggressive modification to get the cutting edges closer to the center point.
I removed quite a bit of material from the end of the bit and completely reshaped the cutting edges to look similar to the 6 inch ice auger. This time the results were excellent. I'd rate the performance at 80%, and the only thing keeping me from calling it 100% was that it was a little hard to get started in a precise spot.
I think this is a worthwhile modification, but the loss of control when starting a new hole is a concern. I think the ideal shape would have a small triangular spade tip instead of a larger screw tip.