After making a bunch of vertical cuts in the sill log, pieces were knocked out with a hammer. Then, the rest was shaved down with the chainsaw to the height we wanted for this window.

Looks good from here!

The rough opening is finished.

One of the rough-cut buck (or casing) boards that will get lag-bolted to each of the exposed logs.

This one is bolted in place.

Note how the sill log sticks out the farthest. This actually works to our benefit for setting the window. A header board will have to go in as well, to bring the top of the casing out to match the sill.