Up to this time there have been several papers on single head twisting drills which gene-rally relate to the drilling of flat planes. But the basic tests described here mainly aim to drill taper planes as well as to make possible one process drilling of countersink and upright hole with a double stepped twisting drill.
These experiments have been made from March 1950 to April 1953, which concern mainly such basic matters as thrust T, twisting moment M_t, and life of drills. Thus it is found that cutting resistance can be reduced considerably by the use of this special type drills and further the experimental formulae about T and M_t of this type are obtained.

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In this research the 12 × 7.2 mm and 8 × 5 mm rectangular blanking tools are used. With the former which is made from high carbon high chromium tool steel No.1, 400, 000 brass blanks of 0.6 mm thickness are cut out and with the latter made from special tool steel No.2, 40, 000 blanks of high class finished mild steel of which thickness is 0.5mm are cut out. The results obtained are as follows:
1. In the sectional shape of blanks, burrs, depth of distortion of blank surface, width of sheared surface and angle of fractured surface increase gradually in proportion to wear of cutting edge, while angle of sheared surface decreases. These phenomena can be seen in both brass and steel blanks.
2. In proportion to wear of cutting edges, the roughness on the side of die and punch edge, the upper surface of die edge and sheared surface of blanks increase gradually in both brass and steel blanks.
3. The outermost dimension of blanks, in proportion to wear of cutting edges, becoms gradually larger than the original one in both brass and steel blanks.
4. And others

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The writer investigated the effects of temperature change on comparators and obtained an apporoximate error formula as described in the paper I and II.
Further investigations are performed in a controlled temperature box provided with a thermostat to reveal the limitations of our error formula and the difference of temperature between the surface of the principal parts of comparator and the ambient air.
According to these results, the formula can be practically applied to many conventional works except very long ones (100mm, or more) having a higher expansion coefficient in rapid temperature change of ambient air, and also considerable temperature difference shows the impossibility of correcting by means of the mere ambient temperature.

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The thickness of chip before removal from the work piece was varied at various cutting speeds, and the temperatures along shear plane were calculated from the data of turning according to the theoretical analysis of heat flow in the previous reports. Especially it is noted that the temperature-rise at the tool-chip-interface which is due to the work done on shear plane decreases with higher cutting speed and/or heavier cut.

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