Electric Drills

Possibly no single tool is more abused than the standard electric drill, and it is always surprising

97 3/8 in (10mm) variable speed electric drill

that it can accommodate such rough treatment. A multiplicity of types is available, from the 1/4 in (6 mm) chuck capacity home model, with a chuck no-load speed of 2600 rpm, to the 11/4 in (32 mm) capacity heavy duty drill running at 275 rpm. Drills over 3/8 in (9.5 mm) chuck capacity are usually two-handed as they have low speed and maximum torque for penetrating the toughest materials, but the usual pattern for woodworking is the pistol-grip drill with a capacity of 1/4 in (6 mm), 5/16 in (8 mm) or % in (9.5 mm), the 3/8 in preferably with two speeds as the normal no-load speed of about 1000 rpm is on the slow side for wood. Capacities up to 3/8 in (9.5 mm) are obtainable in home, general and heavy duty drills, and for use with accessories either the general or heavy duty type should be chosen although the lightweight models will perform an amazing number of operations provided they are not sustained and the feed-rate is gentle. The heavier drills are, of course, more sturdy,,usually double insulated, and some have automatic cut-outs to protect against overload. Drilling capacities are usually stated to be up to 1/4 in (6 mm) in steel and 1/2 in (12.5 mm) in hardwood for the 1/4 in (6 mm) lightweight drill, and up to 3/8 in (9.5 mm) and 1 in (25 mm) respectively for the 3/8 in (9.5 mm) model, but much depends on the type of drill and the nature of the hardwood. Stub twistdrills, jobbers' twist-drills and woodworking twist-drills up to 1/2 in (12.5 mm), flatbit-drills up to 11/4 in (32 mm), and Jenning's pattern dowel- and auger-bits up to 3/4 in (19 mm) are all available with shanks turned down to 1/4 in (6 mm) diameter for drill-guns. Great care should be taken when using auger-bits with screw-points as the snatch at high speed is very considerable, and can be positively dangerous unless the wood is securely anchored down. Speed reduction units are available, also right-angled speed-changers which will either double or halve the stated speed of the drill.

A useful development of recent years has been the cordless drill which has simply to be charged up from time to time from an outlet of the mains supply. It has transformed the noisy, fast electric drill into a lightweight, quiet, refined cabinetmaker's tool. It runs at low speeds and can be used with absolute safety for many delicate drilling operations and even as a mechanical screwdriver.

Wood Working for Amateur Craftsman

Wood Working for Amateur Craftsman

THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.

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