GB1312763A - Film thickness gauges - Google Patents

Abstract

1312763 Dial gauge measuring thickness of coating H TINSLEY & CO Ltd 3 March 1972 [8 March 1971] 6317/71 Heading G1M A gauge for measuring the thickness of a non- magnetic film on a ferrous body 25 comprises, a sleeve 2 slidably positioned for datum purposes at locations 3a 3b of a dial gauge casing, and a tube 6 of aluminium or its alloy slidable in the sleeve 2 and carrying a magnet 7 at one end and at its other end having a plug 8 provided with a brass pin 9 sliding in a slot 10 in the sleeve. The tube 6 has a tension spring 11 fixed to the plug 8 and at its other end the spring is tension adjusted by being fixed to a screw in the end of the sleeve 2. An indicating needle 12 counter-balanced at 14 and pivoted at 13 may be moved from the Fig.1 datum position by sliding movement of the abutting pin 9, which movement takes place when the magnet 7 is attracted to the end of the sleeve 2 by placing the gauge with its end 5 against the ferrous body 25. If the gauge is now drawn away from the body 25 the magnet 7 will be held by the attraction and withdrawn slightly from the end 5, and this movement will slide the pin 9 and move the pointer 12 over the gauge markings. Further movement of the apparatus finally breaks the magnet away from the ferrous body 25 and the magnet then retracts into the tube 6 and the pin 9 leaves the balanced pointer behind which remains in position indicating a reading on the gauge, the final pointer position depending on and indicating the thickness of the non- magnetic film on the body 25. A pointer reset mechanism 19, 20 operated by a plunger 23 is also provided.