Abstract: A device is provided operable by rotary power means such as a common gas powered chain saw with bar and chain removed therefrom or a rotary electric saw with blade removed, which enables easy matching of logs for construction of log houses or other log buildings, the device having means to engage the drive mechanism of the rotary power means, the drive sprocket of a chain saw, the device including an elongated rotatable cutter preferably with multiple blades and having an elongated guide which shrouds all but one side of the cutting blade and which guide provides a means for sliding the cutter along the pre-cut side of one log and enabling the cutting to match that of another log which is placed and spaced in a juxtaposition with the cut side of said log; the movements of the guide along any imperfections in the cut log will result in a matching mirror image cut of the juxtaposed log.