METRIC SCREW THREADS, PRESENT STATUS.

The change-over to metric screw threads is developing in line with adoption of the metric system in the United States. Certain metrix thread standards have been finalized and others are being prepared. Already the picture is becoming clearer to guide American industry in the choice of diameter/pitch combinations and classes of tolerance that are or will be standard, or at least in common usage. From the very wide and complex choices of metric sizes and tolerance classes, common sense dictates the selection of a minimum variety to suit individual product requirements.