A combination of skill saws and chisels are used to cut the desired notches and grooves into the logs. Cypress boards are grooved in the 4th picture before building them into a window or door frame. The 5th picture shows the groove in the outside board on the door frame and how it matches up to the groove cut into the log. That groove is being cut in the 3rd picture. The last picture shows the tongues being removed from a set log to make way for a window frame.