Just   a   little   note   about   English   decimals.   In   the   precision   sheet metal   trade   we   work   with   dimensions   either   in   English   or   Metric   units. When   working   in   English   units   our   dimensions   are   based   on   a   piece   of measurement   called   an   inch.   There   are   still   a   lot   of   places   using fractions   of   an   inch   on   their   blueprints   such   as   1/2"   or   3/4".   When working   with   these   types   measurements   you   should   convert   them   to English   Decimals.   This   is   easier   than   it   sounds.   All   you   have   to   do   is work   the   fraction   like   a   division   problem.   For   example   take   3/4".   On your   calculator   just   do   3   divided   by   4   which   =   .750.   In   the   precision sheet   metal   trade   we   usually   work   in   thousandths   of   an   inch   (.001). Which   means   we   are   just   taking   an   inch   and   dividing   it   into   1000 pieces (1/1000). This is how we pronounce certain decimals: .003  is three thousandths .03   is three hundredths add a zero to the end and it is read as .030  thirty thousandths (it still is the same value as .03 no matter              how many zero's are added to the end) .300  is three hundred thousandths .3    is 3 tenths which is the same value as .300 or .30 .047  is forty seven thousandths .470  is four hundred seventy thousandths Get the drift? Where   that   decimal   is   located   is   very   important.   Some   major   mistakes   have been   made   by   people   who   have   put   the   decimal   in   the   wrong   place,   me included. While   on   this   subject   lets   talk   about   tolerances.   Back   about   fifteen   or twenty   years   ago   the   usual   blueprint   tolerances   for   sheet   metal   parts   might have been: .xxx (three place decimal, thousandths) ±.030  occasionally ±.015 .xx  (two place decimal, tenths)        ±.060  occasionally ±.030 As   equipment   became   computer   operated,   precision   increased   and   tolerances could   be   held   a   lot   closer.   Engineers   demanded   higher   quality   and   tighter tolerances. You may now see: .xxx ±.005 Yikes! .xx  ±.015 or ±.020 Which   means   you   have   a   lot   less   margin   of   error   in   your   flat   pattern.   You need   good   press   brake   operators   and   bend   deduction/bend   allowances   that   you know will work.
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