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SPRING 2021

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Distributor's Link Magazine Spring 2021 / Vol 44 No 2

30 THE DISTRIBUTOR’S

30 THE DISTRIBUTOR’S LINK Larry Borowski President GREENSLADE & COMPANY INC. 2234 Wenneca Avenue, Fort Worth, TX 76102 TEL 817-870-8888 FAX 817-870-9199 EMAIL sales1@greensladeandcompany.com WEB www.greensladeandcompany.com MEASUREMENT OF NON-STANDARD FASTENERS Quite often we get inquiries from customers asking how to measure a particular feature on a special fastener. The “special” part of the fastener can range from material, to machined surfaces on threads or heads, to a special design resembling a faster. It can also simply be a modification to size to accommodate a special coating. Whatever it is that makes the fastener deviate from the standards, results in a “Non-Standard” fastener. Special material can cause performance issues, but in this article we are going to focus on dimensional measurements of non-atandard fasteners, specifically screws and bolts. A screw or bolt can be broken down into two fundamental parts, which we will cover individually. These are the head, which includes the recess or drive feature, and the threads or shank. Measurement of Non-Standard Heads Many times, engineers or end users cannot find a head that meets their needs for the application at hand, and they are not willing to go through the cost of special tooling and processing to get it. The result is a modified head, in some form or another. In these cases, the heads should be checked for conformance to “standard specifications” prior to the modification. After the modification, the feature that was modified should be checked to insure that it dimensionally meets the new criteria. For example, we can start with a ½-13 Hex bolt and reduce the head height and machine two of the flats narrower for a clearance issue. It would be expected that the head be first checked for standard conformance, and afterward be checked that the new height and new across flats dimensions conformed to the new criteria. If these modifications are controlled by a different engineering drawing, that becomes your new criteria for inspection. If you are the manufacturer, care should be taken that the “standard” bolt you are starting with is capable of meeting the new drawing after modification. For example, if the modified head requires a stricter concentricity callout than the standard head, there may be problems meeting the modified print requirements. For those applications where the cost of special tooling and processing is warranted, the sky is the limit on what a fastener head can look like. In these cases, the engineering print takes precedence over any “standard.” TECHNICAL ARTICLE CONTINUED ON PAGE 112

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