The authors designed a new simple involute curve tester for large spur and helical gears. This tester measures the differences between the gear tooth curve and the circular arc in the section perpendicular to the gear shaft.
These differences between the true involute curve and the circular arc, and the expected errors induced by the disposition of centre of the circular arc are calculated and the range of adoption of the curve tester of this type was determined.
Some records as examples were also given with the comments on them.

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In the study of this shearing test, Amsler testing machine, three kinds of round shearing tools of 10mm, 25mm and 50mm in diameter respectively and autographic recorder are employed.The autographic recording system consists of dial gauge with thin disc having fifty slits, photocell, photo-electric-current amplifier with relay, electromagnet with ratchet attached to Amsler recording drum. By these apparatus, approximate shearing curves of round blank are recorded on the drum. The test pieces are of mild steel sheet of 0.96mm in thickness.
The results are as follows.
1) Nominal shearing stress decreases gradually in proportion to the increase of the tool clearance.
2) Nominal shearing stress is 7580% of ultimate tensile strength.
3) The Minimum values of the specific work required in each tool being about 12kg-mm/mm², appear between 8 and 16% tool clearance,
4) And others.

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Quenched carbon steel (0.63%C) test pieces were finished by such various methods as grinding, lapping, superfinishing, supergrinding, emery-paper polishing and electropolishing. The depth of the surface layers of the test pieces thus finished was measured by etching method explained in detail in the first report.
It was confirmed that these surface layers were considerably deeper than we expected, due to the existence of residual surface layers produced by previous finishing (grinding).
The depth of surface layer produced only by the final finishing process can be measured by removing those produced in the previous finishing process.
The results are as follows:
Medium and fine grinding: 7μ and 2.5μ, lapping: 2μ, superfinishing: 1μ.

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A tool dynamometer, which consists of a pair of parallel springs attached to the cutting tool or work and a pneumatic micrometer, is described here. The minute displacement of the former proportional to the cutting force is detected by the latter.
In this paper the following items are involved:
1) Static and dynamic characteristics and measuring force (force due to air jet from the nozzle) of pneumatic micrometer (water column type).
2) Static and dynamic characteristics of parallel springs.
3) Some practical applications: dynamometer for shaping, turning, milling, cutting-off, scratch tests or lapping force, etc., with photograrns.
This dynamometer is not only able to measure the mean cutting force simply and accurately in machine shops, but also to record the instant changes of force in laboratory.

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The characteristic of the surface can be explained by the statistic R/s, (max. range)/(standard deviation).
All surfaces are not of equal characteristic, even though their "peak-to-valley heights " are equal. From the statistic R/s, one can see how the surface is flat or notched.
The effect of electro-polishing to the smoothness of surface is represented by R/s, and it was shown quantitatively.
The reason that the tracer instruments for measuring surface roughness are not available in the case of soft surface is shown quantitatively, and it is proved statistically.

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[in Japanese]

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