A particularly interesting small hand tool with a multiplicity of uses is the electric hammer which has recently been placed on the market by the Rawlplug Co., of Cromwell Road, London, S.W.7. This hammer will bore holes in hard material such as concrete, brick and stone, and can also be used for hacking, pointing, and chase cutting.
The compact design of the electric hammer makes it extremely portable, while the fact that it is suitable for use on either A.C. or D.C. power supplies ensures that it can be used anywhere where there is an electric point. The consumption is approximately 170 watts, which works out at about one-sixth of a penny per hour, assuming that the power charge is Id. per unit.
The motor speed is approximately 1,500 r.p.m., and this is geared to a striker so that 3,000 blows per minute are struck. The striker mechanism consists of a pair of steel balls carried inside a cylindrical rotor under the control of a special type of cam which practically eliminates vibration. There is no danger of the tool-holder being shot out, as it is locked in position and held clear of the hammer until the tool is presented to the surface. A rubber shield prevents dust and debris entering the tool-holder guide.
The drive is taken from the electric motor by means of vee-belts. and the flexibility of this drive prevents any undue shocks on the motor shaft.
As supplied, the hammer is complete with 9ft. of three-core tough rubber flexible cable, special Rawldrills (sizes 6-14), ejector, and tommy bar.
In the speeding-up of assembling operations in mass-production work, the M.A.S. " self-grip " stud driver and extractor illustrated herewith will be found of particular advantage. The makers—M. Semet and Co., Ltd., of 14, Palmers Street, London, S.W.I— claim that it cuts down the time required for inserting or removing studs by 50 to 70 per cent., while in many instances it has proved even faster than power tools.
The ingenious design of the tool will be observed from the illustration. It consists of a self-gripping chuck carried in a lower box socket of the tool. There arc three hardened steel rollers AA mounted in a squirrel cage which is free to move within grooves milled within the lower socket. There is ample clearance between the effective “bore," constituted by the three rollers, and the stud diameter to allow the tool to be freely slipped over the stud and lifted off without damaging the threads.
The profile of the grooves is such that when rotating the tool by hand in either direction the rollers are shifted towards the axis of the stud and locked firmly against the unthreaded portion. Less than a quarter-turn of the hand suffices to obtain this wedging action. To ensure that a grip is secured upon the plain portion of the stud a milled screw and a milled nut provide an adjustable stop.
The M.A.S. tool is complete in itself, and requires no other movement than that of simply turning the handle, as with an ordinary T box wrench. It is already widely used in engineering workshops engaged in the production of such items as aero engines, motor-cars, naval craft, boilers, steam and oil engines, electric motors, tanks, tractors, machine tools, etc. A full list of stock sizes together with a list of prices can be obtained on application to the company at the address given above.
The "TeanTee" blue-printing machine shown in the accompanying illustration has been introduced by the T. and T. Works, Ltd., Billesdon, Leicester, to meet the need of the smaller works and offices for a low-priced, simple and efficient apparatus for this purpose. The price of the "TeanTee" is within the reach of the smallest engineering concerns. There are no installation difficulties (all that is required is an ordinary power plug), operation is easy, and the machine is very simple and reliable.
The tracing and sensitised papers are held in position by a canvas with suitable elastic fastenings, round a semi-cylindrical plate-glass bend. The source of light is two tubular mercury-discharge lamps arranged along the axis of the cylinder, providing a uniform and intense illumination of good actinic quality, so that a fine print may be obtained in as little as twenty seconds. A special feature is the automatic shield covering the lamps as soon as the canvas is released. This not only protects the eyes, but prevents blurring whilst the print is being adjusted.
The chokes for the lamps arc arranged in a neat bos, and the whole apparatus is remarkably neat and light. The standard model takes drawings up to 22in. x 18in., and a smaller one is available, suitable for many requirements, taking up to 15in. x llin.