Okay, there's probably a better way to do this but this worked for us! We used a single drill bit to create a circular pattern through the log wall and then, eventually, punched the entire hole out to fit the vent. The vent was insulated to insure there wouldn't be too much heat inside the log.
Here's my personal webpage about energy:
http://www.rogerwendell.com/energy.html
Here's my page about solar energy:
http://www.rogerwendell.com/solar.html
Here's my page about wind energy:
http://www.rogerwendell.com/wind.html
11-13-2018