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Dimensioning Internal Features
Dimensioning   internal   features   is   done   the   same   way   as   figuring developed    lengths    or    widths.    Bend    deduction    or    bend    allowance compensation   has   to   be   used   when   calculating   the   placement   of internal    fea - tures.    Holes    and    cutouts    can    be    dimensioned    on blueprints   many   different   ways.   Some   of   these   can   be:   from   outside apex   of   material   of   a   bend,   inside   apex   of   material   of   a   bend,   or from an outside edge of the part. In   the   illustrations   below   the   top   picture   is   a   representation   of a   formed   angle   as   it   would   possibly   appear   on   a   blueprint.   The   hole and   cutout   is   located   from   the   outside   apex   of   the   material.   Since this   is   a   ninety   degree   bend   it   is   also   tangent   to   the   bend.   to calculate   the   placement   of   the   hole   from   the   bottom   of   the   blank   you would   take   .620   minus   the   bend   deduction   of   .123   and   then   add   1.175 giving you 1.672.
When    you    get    to    the    acute    and obtuse   bend   sections   remember   that internal    features    are    calculated the   same   ways   that   are   used   for developing    overall    lengths    and widths.    Just    imagine    that    the dimensions   used   from   the   bends   to the    outside    edges    are    going    to internal features instead.
Use .123 Bend Deduction
FLAT PATTERN SAMPLE 2 Dimensions placed from top of flat part
FLAT PATTERN SAMPLE 1 Dimensions placed from bottom of flat part