Drill bit

Drill bits are the cutters of drill tools. Bits are interchangeable, meaning that they can be removed from the end of the drill, either to replace a worn part or to change the size of the part.

PCB through-hole drill

Printed circuit boards are usually made of fiberglass, which due to being highly abrasive, would quickly ruin a normal drill bit, especially given the many hundreds or thousands of holes on most circuit boards. To solve this problem, solid tungsten carbide twist bits are almost always used, which drill quickly through the board while providing a moderately long life. Carbide PCB bits are estimated to outlast high speed steel bits by a factor of ten or more.

Related Topics:
Printed circuit board - Fiberglass - Tungsten carbide

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In industry, virtually all drilling is done by automated machines, and the bits are often automatically replaced by the equipment as they wear, as even with their solid carbide construction, they still have a short lifespan. PCB bits typically mount in a collet rather than a chuck, and come with standard size shanks, often with pre-installed stops to set them at an exact depth every time when being automatically chucked by the equipment.

Related Topics:
Automated machines - Collet - Chuck

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Due to the high RPM these bits are used at (30,000-100,000 or higher is common), their small size, and the brittleness of the material (even the slight wobble of an operator's hand will shatter one, as will accidental contact with most any object), they must only be used with extensive safety precautions, as a shattered drill bit can easily penetrate skin (and be an expensive mistake!). Due to their delicate nature, these bits should absolutely never be used in a hand drill, and even most moderately expensive drill presses will have too low of an RPM and too high of a chuck wobble to use these bits without breaking them.

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Image:Two pcb bits.jpg|Two PCB drill bits.

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Image:Box of 02in pcb bits.jpg|A box of #76 (0.02in) PCB drill bits.

Related Topics:
#76 - In - PCB

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