TM 9-243 USING ELECTRIC BENCH GRINDERS – CONTINUED · Ensure   that   wheel   guards,   tool   rests,   and   shields   are properly positioned before applying power. · Stand  to  the  side  of  the  grinder when   turning   it   on.      Allow   the machine   to'   run   for   one   minute before   engaging   the   wheel   with the  work.    The  turn-on  period  is the most likely time for a wheel to break. · Keep  the  tool  rest  as  close  to  the grinding wheel as possible (approximately 1/16 inch) when using   the   grinder,   take   small   cuts with moderate pressure. · Never use a glazed, worn, or uneven wheel: replace it. · Never  operate  the  grinder  or  attempt  any  repairs  without having a thorough knowledge of the grinder's operation. PORTABLE ROTARY POLISHERS AND GRINDERS Portable  rotary  polishers  and/or grinders   are   either   electric   or pneumatic     powered     types     of various  speed  ranges.    Wheels used   on   these   tools   vary   from coarse   grit   for   metal   removal, fine grit for paint or rust removal, to soft fabric material for polishing surfaces. When    mounting    wheels    on    spindles,    the    following    procedures should be used: Inspect the grinding wheels for flaws and make the "ring" test. Clean  the  bearing  surfaces  of  wheel,  flanges  and  spindle  so that clamping pressure will be evenly distributed. Make   sure   that   the   hole   in   the   wheel busing   is   the   right   size   for   the   spindle (neither too small nor too large.) Use  flanges  that  are  recessed  and  large enough  to  clamp  the  wheel  well  toward its circumference. Tighten  spindle  end  nuts  just  enough  to keep    the    wheel    from    moving    out    of position between the flanges. WARNING Eye protection must always be used when operating  these  tools.    A  grinding  wheel that  has  a  glazed  surface  or  an  uneven wheel should never be used. CAUTION · A  hand  held  polisher  or  grin der  must always be equipped with an operating switch  that  is  either  spring  loaded  or air    pressure    loaded    to    the    cut    off position   to   cut   off   power   when   the hand  grip  is  released.    Tools  without this equipment should be discarded. · Grinding wheels used must  always be rated  at  a  speed  equal  to  or  greater than the tool it will be used on. · These  tools  should  only  be  used  on objects that are either massive enough or restrained to prevent grinding  or  polishing  from  moving  or throwing   the   object.      This   tool   shall never  be  used  to  grind  or  polish  an item that is held by hand. · These   tools   will   never   be   equipped with  a  tool  rest,  but  must  always  be equipped  with  a  guard  that  will  cover not less than one half the periphery of the wheel being used. Change 3  52-14.1/ (52-14.2 blank)