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Metric and imperial hand drills and braces

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Braces are often measured in imperial measurements of their sweep size. The imperial and metric measurement systems apply to the sizes of hand drills and braces. Since braces were in use before the metric system was devised, they were sized with the imperial system.

Braces are sized according to the sweep of the handle, measured in inches and range from 6″-14″ in size. As the imperial system had already become the standard way of sizing a brace, it has continued to be used for this.

The length of a hand drill will often be stated in both metric and imperial measurements. Hand drills were first developed at around the same time as the metric system became used, so their sizes or lengths from the chuck to main handle or breast plate are often given in both metric (millimetres) and imperial (inches).
Chucks of hand drills and braces can be sized in both imperial and metric measurements The chuck size is most frequently given in millimetres, although on hand drills and braces sold or manufactured in the U.S. it is more likely to be given in fractions of an inch.