Twist and spade bits work OK but auger bit works the best.
One winter when I lived in Minneapolis I made large ice votives. It took a little experimenting but I got it down.
Round five gallon bucket
Round 2 gallon bucket filled with rocks hanging from an adjustable length cord from the ceiling
Fill 5 with water then set the 2 gallon inside. Top off the fiver. Adjust the length of the cord so that the rim of the 2 is even with the top of the five. Leave the water to freeze. Keep a note of time and temperature so you can get a rhythm.
When the ice has frozen to a desired thickness pull out the 2 gallon. To make the nicest globes you'll find that the ice will freeze thickest on the bottom then a bit thicker on the sides. The top will freeze too but not 'freeze in' the rock filled bucket. With good timing you'll have a chamber inside that is sorta round with some water in it. Pour the chilled water in your next 5 as a starter. Set the ice votive aside to freeze solid. Most of the time the votive will slide out of the bucket/mold. If not, dipping it in a bigger bucket will thaw the surface a little. I found that having the side shell about 1/3 frozen worked best.
Once you get your system you can start a factory in the garage.
The 5ers last a LONG time! They are deep enough so that the wind doesn't blow out the candle. Kind of like a hurricane chimney.
A friend took this idea and got really creative. He put die in the water. On some of the molds the die separated as it froze leaving a darker ring at the bottom and lighter colors towards the top. Then he started freezing in layers with the 5er sitting flat. That lead to tipping the bucket to make angled layers...wild stuff but way too involved for me. Artsy cooks do the same with Jello sometimes!
I would love to do the same but Austin is way too warm