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Double margin drill bits have an additional margin ground behind the leading margin, providing twice the number of contact points. This second margin
performs various functions to improve hole quality. The trailing margin burnishes the cavity, making a true hole and smoother finish, helping to provide a more
concentric drilled hole.
Bit Size: #13
Pilot Size: #30
A reamer finish can be achieved with double margin bits, eliminating a second operation.
When a double margin bit is used with a drill bushing, the four margins locate in the bushing, providing increased bushing support in excess of 200 percent.
When intermittent cutting is required, the double margin bit performs in two ways: enhanced margin support in the first cavity cut, and support on
breakthrough, which stops the drill from wandering when in contact with the work piece.
Drill back taper is more tightly controlled than a regular drill bit, enhancing a rounder hole location.
The 135 degree split point provides immediate self-centering on contact with the work piece.