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Improved Hole Measurements Using Tapered Mandrel Gages

IP.com Disclosure Number: IPCOM000043799D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Mannheimer, R: AUTHOR [+2]

Abstract

Disclosed is a method for measuring the diameter of the punched center holes of diskettes more accurately than previous methods. The improved method provides better precision, accuracy, and replication. Prior-art measurement methods involved lowering a diskette with a punched center hole onto a mandrel structured with increasing diameter steps. The test, essentially a "go-no go" type, was undependable because the diskette tended to hang up on the next smaller dimensional step from that it would actually fit over. Additional errors were caused by variations in descent speed of the diskette. The force at which the diskette was applied to the stepped mandrel was proportional to the speed of descent which was manually controlled by the operator. Because of variations in speed, nonpredictable errors were introduced.

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Improved Hole Measurements Using Tapered Mandrel Gages

Disclosed is a method for measuring the diameter of the punched center holes of diskettes more accurately than previous methods. The improved method provides better precision, accuracy, and replication. Prior-art measurement methods involved lowering a diskette with a punched center hole onto a mandrel structured with increasing diameter steps. The test, essentially a "go-no go" type, was undependable because the diskette tended to hang up on the next smaller dimensional step from that it would actually fit over. Additional errors were caused by variations in descent speed of the diskette. The force at which the diskette was applied to the stepped mandrel was proportional to the speed of descent which was manually controlled by the operator. Because of variations in speed, nonpredictable errors were introduced. A preferable measurement technique involves use of a tapered mandrel, placing the diskette onto the mandrel so that it is positioned at a point where the diameter of the diskette hole is the same as the diameter of the mandrel. The mandrel is graduated by markings that indicate the diameters at the marked points. The accuracy of the measurements depends on how close the marked diameters are to the actual diameters at the marked points. The precision of the measurement depends on the amount of taper that can be tolerated. A wide taper will have less precision than a narrow one. Therefore, for precise measurements, the taper should be small. For accurate measurements, the taper should be large. The decisive factor for the taper is the tolerance range that must be maintained in the measurements. Placing the diskette on the mandrel with predictable force r...