Drill support
Patent 5275514 Issued on January 4, 1994. Estimated Expiration Date: 
December 9, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 9, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesRe33145 InventorAssigneeApplicationNo. 988175 filed on 12/09/1992US Classes:408/76, Magnetic or suction means408/710SAFETY DEVICEExaminersPrimary: Howell, Daniel W.Attorney, Agent or FirmForeign Patent References
International ClassB23B 045/14Foreign Application Priority Data1992-01-29 GBAbstractA portable workpiece-mounted machine tool such as a drill is provided with a permanent-electromagnet attaching unit which has its reversible permanent magnets alternating with nonreversible permanent magnets so that, when electric current is applied to the reversible magnets, they are subjected to polarity reversal which causes flux closure through a workpiece of the reversible and nonreversible magnets in the "on" position and causes flux closure between a reversible and nonreversible magnet in an "off" position. | |
