DRILL AND TAP SIZING CHART
Table of drill and tap selections necessary to drill and tap holes for mounting holding block to strut or stern tube.

SCREW SIZE

TAP DRILL SIZE

TAP SIZE

5/16 X 18

17/64 or F or I - .257 - .272 5/16 X 18

3/8

5/16 or P - .312 - .323 3/8 X 16

STEP 1: Use regular starter tap.
STEP 2: For shallow holes, use a bottoming tap to complete threads to bottom of drill hole.

 

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