In order to construct an inside gauge, gauge blocks and jaws are wrung together and mounted on a holder. This inside gauge is inserted into a hole to measure its internal diameter.
The process of measurement consists in varying the sizes of the gauge blocks by steps of 1μ until a nice fit is obtained. By this method it takes long time to measure internal diameter precisely. On the other method, an inside gauge is constructed slightly smaller than the diameter of hole. And one jaw is kept to be contact to the wall of the hole, while other can he swung in the hole. The displacement of the movable jaw is measured by a dial gauge to obtain the internal diameter. Through the latter method, the measurement is very simple and carried out rapidly. In this report it is described how rapidly and.accurately the measurement can be carried out by the latter method.

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This paper presents the results of an investigation of the frictional effect on cutting forces in metal cutting. What is called the coefficient of friction especially in the case of metal cutting is actually the apparent coefficient of friction.
The real coefficient of friction is nearly constant, or independent of the rake angle of a tool at least. And it depends on the properties of the material, the condition of the tool surface, and the temperature of the contact surface, etc.
The theory of these phenomena is discussed in term of basic variables in chip formation. The fundamentals of chip formation are largely affected by the accuracy in measurement of cutting force under normal cutting conditions.
The primary requirement for the dynamometer is sufficient stiffness, and the second is high sensibility.
For this purpose, the authors made a three-dimentional tool dynamometer with a tubular tool holder. For measurement of interface temperature, a compensating circuit Is used to minimize the effect of parasitic electro motive force, induced by use of a lead dissimilar in composition to the carbide tip.
These results are shown graphically in Fig.5-10, then the considerations or discussions on the friction in metal cutting.
From these analyses, it can be concluded that the apparent coefficient of friction (μ) is defined by the real coefficient of friction (μ₀) and a function of the rake angle (α), as shown Eq. (5), (6).

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In previous reports, the authors showed that to assume metal cutting process as a plastic compressing process was reasonable, and that so called coefficient of friction μ in the case of metal cutting is expressed by μ=tan α+μ₀ where α is rake angle and μ₀is real coefficient of friction in metal cutting.
In this paper, a new model of chip formation is introduced by applying the Prager's theory of plasticity, and the variation of the normal stress upon the tool surface due to the difference of the rake angle of the tool is found. And the authors introduced a formula of cutting forces.
In order to estimate the rate of material softening at the elevated cutting temperatures, the impulsive hardness of the materials was measured at high temperatures.
The machining variables computed by the author's theory were compared with the experimental data.

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Recently, the discharge machining has become very popular in the field of precision machining and with the development of its practical use in this field, various studies on mechanism of discharge machining have been carried out with the publication of several interesting opinions.
It is recognized by the most that the important factors in discharge machining mechanism are energy of heat and physical force at the discharge.
Since discharge machining is a series of repetition of a capacity discharge in the small gap length in liquid insulator, physical quantities at a single discharge must be clarified.
The author measured the discharge shock force quantatively.
In this measurment, BaTiO₃ ceramic was used as a piezoelectric element and the faithful measurement was performed by liberating the shock force to the piezo-pick up from both sides at the same time.
In this paper, the principle, the apparatus used and the results obtained are described.

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In order to make clear the mechanism by which material is removed in ultrasonic machining, the following observations and discussions are described.
(1) Appearance of a chip removed is like that of a plate, the diameter of which is larger than ten times of its depth. Chips, the diameters of which are larger than that of an abrasive particle are often found.
(2) The size of a trace left on the work surface is almost similar to that of a chip removed in view of form, diameter and depth.
(3) Surface roughness which is expected from thickness of chip removed and depth of trace left is obtained.
(4) Residual strain under the trace left is very small in depth.
(5) Machining depth per one cycle is far smaller compared with thickness of chip removed, depth of trace left and surface roughness.
By comparing mean machining volume per one cycle with calculated volume from the above observation and effective number of active abrasive particles, the following conclusion is obtained. If we observe one paticular chip, it is considered that the chip is not removed until the strain originates and grows enough up to a crack by repeated impacts between the horn tip and the work surface through one particle in a chance and another one in after chance, while cavitations which permeate easily into the micro crack may help the growing up of the strain and the tearing-off of the chip.

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Thermal stress resistance test apparatus, in which heating and cooling is repeatedly alternated, was newly devised. And by use of this apparatus, ceramic and carbide tool tips are given thermal stress cycle in order to obtain cracks on them. Measurements were performed on the frequencies of thermal stress cycle to yield cracks on the surface of the tips.
As the result, cracks were found to appear in a certain probability which is related to thermal stress as well as to volume of test piece. Thus it was proved that cracks recognized at the cutting edge of carbide face milling cutter are attributed to the repeated thermal stress thereupon.

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