IMPRINTING PRESSURE by Charles Cassagnal March 25, 2003 First,   imprinting   force   or   pressure   is   not   an   exact science,   just   a   rough   approximation.   Even   then we    are    only    considering    static    not    dynamic pressure.   Just   as   the   pressure   in   your   car   tires   is   static   to   be   measured   when   cold and   your   blood   pressures   are   static   to   be   measured   at   rest. At   the   current   state   of the   art,   the   specifications   call   for   an   imprinting   static   force   or   weight   ranging   from 500   to   1000   lbs   per   foot   of   imprinting   roller   length   for   soils   ranging   from   soft   to hard.   This   weight   range   corresponds   roughly   to   an   imprinting   pressure   range   of   15 to 30 psi. Here is the way I convert from pounds per foot to pounds per square inch. Assumptions: • That   only   3/4   of   one   imprinting   tooth   is   fully   in   contact   with   the   soil   per   foot of roller length. • That the tooth is made from a 10-inch length of 6" x 6" angle iron. • That the tooth width in soil contact is 4.24 inches. • That   the   tooth/soil   contact   area   is   given   by   the   product:   ¾   x   10   x   4.24   = 31.8 in. 2 • That   the   unloaded   (without   ballast)   weight   of   the   seeding   imprinter   is   500 pounds   per   foot   of   roller   length   and   that   the   weight   of   ballast   is   500   pounds per foot. Then the imprinting pressure without ballast is: Pressure (no ballast) = 500 lb 31.8 in 2 = 15.7 psi And: Pressure with ballast = 1000 lbs 31.8 in 2 = 31.4 psi Finally: Pressure without ballast = 15.7 or about 15 psi Pressure with ballast = 31.4 or about 30 psi So,   in   conclusion   the   current   specs.   call   for   a   range   in   static   imprinting   force   of   500 to   1000   lbs   per   foot   of   imprinting   roller   length   corresponding   to   an   imprinting pressure range of about 15 to 30 psi.