Steel still ranks as the commonest and most used metal. With increased competition between manufacturers to produce the bit with the sharpest cut and the smoothest edge bits, a number of materials have been incorporated in Forstner bit metals to improve qualities such as durability and resistance to rust. Ensure that the borehole is cleaned out every fifteen to twenty seconds to prevent clogging which will also cause blunting. The larger the bit, the more easily it will be damaged by high speed. To maintain the strength and sharpness of the bit, use lower speeds. In use, Forstner drill bits tend to heat up, which leads to blunting. They are best stored in a case where they cannot roll around, preventing damage to the cutting edges.Įach time you use the bits, clean them with a wire brush and some three in one dry lube to maintain their sharpness. Good drill bits are expensive, but when treated with care they can last for years.
Forstner bits do not have flutes that can pass chips up and out to the surface of the piece being drilled, so it's necessary to lift the bit out of the bore, or almost out of the bore, every 15 to 30 seconds. The list below shows the safe running speeds of different sized Forstner bits, with the smaller sizes able to run at pretty much the same speeds as twist drills, while the larger sizes-at the top of the lists-must move more slowly.Īn important step in the interest of keeping your Forstner bits sharp and in good shape is cleaning the hole bore often. Hand drills can't be as tightly speed regulated as can drill presses, so constant attention to their speed is essential: in fact, though, it's really best not to run Forstner bits in handheld drills, because of the lack of speed control (and accuracy-Forstner bits are made for clean, neat, accurate holes, which is seldom what a handheld drill produces, regardless of bit type). If you're using a trigger controlled hand drill, set it on the lowest possible speed range, and then pay strong attention to the actual speed of the drill chuck. The first job, then, is to limit the speed of the drill you're using, whether a hand drill or a drill press. Both, though, work far more efficiently within clean holes, so the clean-out requirement remains. That said, high speed steel (HSS) Forstner bits don't lose temper easily, and carbide tipped Forstner bits are even sturdier. If the bit body heats up enough, the heat draws the temper from the bit. What happens is simple: because of the bulk of the bit's body, it heats up rapidly, so that you must keep speeds down (compared to possible speeds with HSS standard drill bits and even those allowable with brad point bits). The larger the Forstner bit, the faster it can be ruined by excessive speed. Excessive speed, or too much force without a break, can ruin the bits in seconds. With all their good features, we don't use them for every job because they're a little bit fragile, compared to other step drill bits. Consequently, you can use them drill partial holes without any drag caused by the wood grain. These bits can be used to drill holes that partially overlap or holes on the edge of the wood that other bits cannot manage. While spade bits and hole saws can be used for making holes in wood, the Forstner bit provides the cleanest finish. They have radial cutting edges which allow them to clean the wood off the bottom of the hole, working like a rotary plane.
They have a cutting edge or rim that makes a clean cut on the sides of the hole, and a scraping edge that ensures the bottom of the hole is smooth. All Forstner bits have a centering pin for accurate location.
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