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In this paper, it is reported that tapping resistances in the mechanical tapping using a tapping attachment were measured by a mechanical tool dynamometer constructed newly and connected to an oscillograph through an electric resistance strain gauge. The materials used were low carbon steel, cast iron, brass and aluminium. The diameters of the hand tapps were 3/16'', 1/4'', 5/16'', and 3/8'' Whitworth. As the result, the tapping resistance is not merely affected by the tapping speed but depends on the diameter of the tap drill and the form of the chamfer and the flute of the tap.

The causative factors of full porcelain veneer crown failures have been pointed out. For many years, the primary thought has been to construct full porcelain veneer crowns with as much bulk of porcelain as possible but with little thought to the requirements for the individual case. By making an accurate analysis of mandibular function, a guide is established for the amount of tooth reduction necessary for full porcelain coverage. By adequate tooth support to the porcelain, the need for bulk of porcelain decreases, and tooth reduction can be kept to a minimum. By utilizing a chamfer preparation at the labial gingival margin of anterior teeth, excessive tooth reduction can be eliminated, and the porcelain can be laid on the dentine just as the enamel covering has been on the teeth. Soft tissue irritation is eliminated by the protective contour of glazed porcelain, and instead of gingival recession, the gingivae will hug the porcelain crown and remain firm and healthy. Full porcelain veneer crowns can be ground accurately to balanced occlusion by painting the opposing teeth with an oil base pigment, such as Prussian blue thinned with eugenol or a thin sweet oil. Colored paper or cloth interposes bulk between teeth, thus creating a tendency to grind the completed crown out of occlusion.

This paper deals with the variation in discharge of small submerged orifices used in aero-control systems. It is shown that the effects of cavitation can be high and can cause changes of discharge coefficient greater than those associated with Reynolds number when the flow is turbulent. The orifice length was altered and it was found that the most unstable conditions occurred when the length was half the diameter. Further tests were carried out with inlet chamfer in order to determine the optimum angle and depth of chamfer for cavitation suppression.

In externally pressurized gas-lubricated circurlar thrust bearings, the occurrence of depression in the pressure profile is observed under some working conditions. Following the previous paper on the theoretical investigation of pressure depression, this paper investigates theoretically the pressure distribution in externally pressurized circular thrust gas bearings with a circular recess by assuming the generation of a normal shock wave in the bearing recess. Good quantitative agreement is found between the analytical results and available experimental data except the case of small bearing clearance height or deep recess. In order to prevent the pressure depression just after the gas supply hole, it is effective to provide a round or tapered chamfer at the entrance edge of the hole to the bearing clearance or to make the recess tapered doubly. Through these alternations, the shape of pressure distribution becomes flatter so that the load capacity can increase remarkably.

A simplified method was developed by which three-dimensional composite photoelastic models were constructed. The optimum marginal configuration for the stress distribution was determined and was found to be of the chamfer type.

The relationship between preparation finish line configurations and marginal stability of porcelain-fused-to-metal restorations during the firing cycle was studied. Four labial finish lines presently in use were examined. The shoulder finish lines, with and without a bevel, were found to produce significantly less distortion in labial margins of porcelain-fused-to-metal restorations than do chamfer finish lines with and without a bevel.

REFERENCE has frequently been made to the increase in the discharge coefficient of chamfered orifices and nozzles, yet few investigations have been made to study these variations in detail. The experiments described in the following were carried out in an attempt to clear some of these points.

The accurate measurement of small discontinuities in microstrip by conventional means is limited by the imperfections of the microstrip to coaxial transition. By using a resonant technique where such imperfections cause only 2nd-order errors, the equivalent circuit of microstrip discontinuities can be measured. To demonstrate the method, a 90° corner, with and without a chamfer, has been measured.