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=== Hinge sinker bit === | === Hinge sinker bit === | ||
[[Image:drill tip 30mm hinge.jpg|right|thumb|200px|30 mm hinge sinker bit]] | [[Image:drill tip 30mm hinge.jpg|right|thumb|200px|30 mm hinge sinker bit]] | ||
The hinge sinker bit is an example of a custom drill design for a specific application. Many European kitchen cabinets are made from [[particle board]] or | The hinge sinker bit is an example of a custom drill design for a specific application. Many European kitchen cabinets are made from [[particle board]] or medium-density fibreboard (MDF) with a laminated plastic veneer. Those types of [[pressed wood]] boards are not very strong, and the screws of butt [[hinge]]s tend to pull out. A specialist hinge has been developed which uses the walls of a 30 mm diameter hole, bored in the particle board, for support. This is a very common and relatively successful construction method. | ||
A Forstner bit could bore the mounting hole for the hinge, but particle board and MDF are very abrasive materials. Softer steel cutting edges soon wear. A [[tungsten carbide]] cutter is needed, and making that in the form of a Forstner bit is impractical. So, this special drill is commonly used. It has cutting edges of tungsten carbide brazed to a steel body. A centre spur keeps the bit from wandering. | A Forstner bit could bore the mounting hole for the hinge, but particle board and MDF are very abrasive materials. Softer steel cutting edges soon wear. A [[tungsten carbide]] cutter is needed, and making that in the form of a Forstner bit is impractical. So, this special drill is commonly used. It has cutting edges of tungsten carbide brazed to a steel body. A centre spur keeps the bit from wandering. |