Above- 2 1/2 minute video showing how to carve an ice sphere
Below- Step by step instruction

Square up a block with a chainsaw
For a large sphere freeze 2 pcs. together.
This cube is 15” x 15” x 15”
Starting with a perfect cube will allow you to make a nice sphere
Multiply the width of the cube by .29
(Example- 15 x .29=4.35”) Scribe lines
on all sides of the cube 4.35” from the edge
Use a Layout Jig to scribe the lines
With a chainsaw cut off the 4 corners
(Hexagon from top view)Be careful not to cut inside the lines

Rotate the Ice & cut off 4 corners, using the lines as guides

Notice the foam under the carving? This protects your saw

Rotate the ice & cut off 4 more corners, again use the lines as guides
Using a sharp chisel
Carve 3 hoops around ice
Using the chisel
Remove the 8 humps
Using a Sphere scratchy board
Remove the high spots
Scratch the whole surface
in a circular pattern
Using sand paper
sand the whole surface
Spray with a hose set on gentle.

The above sphere took 45 minutes to make using these methods (including photography).

My system is a compilation of the following 3 techniques-
1. The Old Japanese “Carve 3 Hoops” technique.
2. The “Make an 18 sided shape” technique.
3. Junichi’s “Finish with the sphere scratchy board” technique.