Drill crank
A Bohrkurbel (also: brace , crank drill , breast lyre ) is a hand drill , with which it manually by crank technique holes (usually in drilling wood ). Its cranked axis is driven by hand via a loosely mounted grip roller (mostly made of beech wood) that is located on it and rotates outside the drilling axis. In the case of upscale versions, it is also ball-bearing.
functionality
The ball-bearing chest button (also mostly made of beech wood), located opposite the drill chuck (depending on the version max. Span 16 mm, 2–4 clamping jaws), is used to guide the drill and to feed it. The so-called breast button, which lies in the drilling axis and in which the cranked axis rotates, should, under certain circumstances, also enable pressure to be applied with the breast and, where necessary, thereby free the hand that is not cranking (e.g. to hold / counter-hold the workpiece , Self-protection in difficult working conditions). There are two switchable pawls on the drill chuck, which have the effect of a ratchet and thus help to work under spatially restricted conditions. Due to the leverage effect and depending on human strength, the projecting bracket produces a greater torque than other non-electric hand drills; you can therefore drill much deeper and wider holes than with these. Compared to some electric hand drills, a drill crank achieves a higher torque, but it also drills considerably more slowly. An electric motor-driven hand drill can easily reach 2000 or more rotations per minute. A drill crank therefore needs significantly longer for the same borehole. It is also difficult to keep a drill jack completely at the desired drilling angle when preparing a hole, which makes it unsuitable for precision drilling. In addition to drills, this simple machine can also accommodate bit holders or long bits and thus serve for screwing. The main advantages of the drill crank compared to electric drills are the relatively low purchase price and the independence from electricity. Their robust simplicity makes them reliable and largely maintenance-free - only seldom oiling of the ball bearings and the drill chuck is required. With the appropriate material quality and processing as well as storage in the dry, the drill crank lasts almost indefinitely. It is less complicated and more environmentally friendly than its electrical competitor, both in terms of production and disposal. Their low image and market value also make their theft comparatively unlikely.