The Technique of FURNITURE MAKING

ELECTRIC DRILLS

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

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 twist - drills, 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 /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 right­angled 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.

Accessories for electric drills

Numerous accessories are obtainable for sawing, rebating, jigsawing, sanding, polishing, etc., but these are, in the main, hobbyists' tools. One accessory, however, is very useful and calls for mention.

Vertical drill-stand

Vertical pillar drill-stands with spring-loaded instant-return feed and fixed table are usually available for all models of hand drills. With the gun clamped in position the stand becomes an effective vertical table-drill or drill-press for vertical drilling of wood and metal. It lacks the versatility of the orthodox drill-press but will perform most of the main functions of the heavier tool.