In a study by Grandjean et al. (1952) the physiological efficiency of various types of timber saws was investigated. oxygen consumption was measured before and during the use of five different types of saw and the number of work joules calculated. This energy consumption, related to cutting slices or discs 1 m2 in area is shown in Figure 6.4 The results show that the best saws were the two ripsaws with a broad blade and either two or four cutting teeth in each group and these saws were preferred. A more extensive study showed that the best results were obtained from a sawing rate of 42 double strokes per minute and a vertical force of about 100 N