Absence Of Vibration Research Articles

Improved cord machine for planing.

The driving unit for the cutting tool in dermabrasion consists of a motor and a means of coupling to the handpiece. The commonest type is the motor and flexible shaft which was used by Kurtin. A short compact motor and chuck without the flexible shaft, such as the grinding tool used by mechanics, where the entire unit is held in the hand, has also been used. A third method is that of hinged arms and cord and pulleys to drive the chuck holding the cutting tool. This is the type used in the usual dental unit. High-speed motors and transmissions are available which make this type equal to the others as far as speed of revolution is concerned. There is one advantage to the cord and pulley machine not present in the others—the relative absence of vibration in the handpiece. This is very quickly appreciated by anyone

259. A note on a simple and accurate viscosimetric form of rennet test

Since publication (1) the apparatus previously described by the authors has been altered and improved. The alterations have been concerned mainly with excluding draughts and securing a better form of support. In using the apparatus we have found that the absence of vibration is important for the agreement of duplicates. It would seem that vibration tends to break the cohesion between the curd and the surface of cylinder A. For this reason a part of the laboratory as free as possible from vibrational disturbances was chosen and the support fixed to the wall.

A method of measuring mechanical impedance

The device the mechanical impedance of which at a given frequency is to be measured is driven by one prong of an electrically-driven tuning fork, and the other prong is loaded to restore balance, the load required being the mechanical impedance to be determined. The balance condition is indicated by the absence of vibration of the fork support.An improvement depends upon the experimentally determined fact that mechanical resistance out-of-balance does not appreciably affect the support vibration. If the prongs are balanced for mass, the total resistance can be found from a decay-factor determination or by a single measurement of amplitude with a known current, and the resistance of the device estimated.A measurement is made of the mechanical impedance at 100 cycles per sec. of a certain gramophone pick-up.

Tungsten-Carbide Cutting Tools

Abstract Results are given in the fabrication of tools of tungsten carbide, and experiences are detailed of successful and unsuccessful attempts to apply them to various kinds of work. Readjustment of manufacturing practices must take place if there is to be a place in industry for tungsten carbide. The present high price may have its effect upon general adoption. The future of such alloys as factors in efficient manufacturing is asserted to be in the hands of the users of machine tools and not the makers of tool materials nor of the machine-tool builders. The rigidity and absence of vibration in the machine tool must continue, even as it grows appreciably older, to permit these materials to operate without chipping. An even stronger and tougher alloy may become necessary.

The Prerequisites of Successful Polishing

Abstract The author discusses those conditions which must be obtained in the polishing department to procure the highest quality of work with the least cost of material and wages. The most important consideration in successful polishing is the glue used in bonding the abrasive to the wheel and its treatment. The next most important consideration is the selection of the abrasive. These are discussed in detail. Other important factors are: the design of the article to be polished, relation of operations preceding polishing, absence of vibration, housing of the polishing department, polishing machines, automatic polishing, and polishing tools.

Absence of Vibration in a Turbine Steamship

RETURNING homeward to Paris the middle of September from the Tripoli eclipse, and finding passage to America difficult to obtain, I chanced to learn that the triple-screw turbine steamer R.M.S. Virginian was sailing from Liverpool for Montreal on September 30, so I was very glad to have the opportunity of a voyage in a ship full powered with this novel type of propulsion. After a week on board I have no hesitation in saying that for freedom from the nerve-annoying tremors incident to the usual reciprocating engines, the Virginian has proved far and away the quietest steamship I have ever voyaged on. Excellent evidence of this, I think, lies in the exceptionally large number of passengers who dined comfortably in the saloon at the roughest period of our entire passage. There was a fairly heavy sea on, and the ship was by no means free from wave-origined motion. So I am quite of the opinion that sea-sickness and all its train of discomforts must be greatly aggravated by the engine-borne tremors of the ordinary steamship, and that many people who are delicate sailors under ordinary conditions might take ocean journeys with comparative comfort in a turbined ship.