Handheld low voltage machining tool

摘要

A handheld low voltage machining tool with which any one or more of drilling, milling, and abrading operations can be safely performed even on densely populated, multilayer, circuit boards. Provisions are made for preventing electrical overstress by isolating the tip of the machining tool from the drive motor as well as for preventing abrupt starting of the tool which can cause jerking, jumping or skipping of the tool off of the target. Still further, dynamic braking of the tool bit is achieved, both upon release of an operator actuated control switch and due to a selected conductive layer being reached. For the latter effect, a probe is provided by which a low voltage can be delivered to a component or conductor on the board, and circuitry detects grounding of this voltage by contact with the grounded bit of the machining tool.