A dermatome assembly is operable to harvest a skin graft and includes an ultrasonic dermatome and a power supply. The ultrasonic dermatome includes a body and an ultrasonic blade assembly mounted in the body. The blade assembly includes a frequency generator and a cutting horn powered by the frequency generator. The cutting horn is spaced apart from the body so that the body is restricted from damping vibrational movement of the cutting horn. The dermatome assembly is operable to precisely control the thickness of the cut skin graft and also restrict the cutting horn from overheating.