TM 1-1500-204-23-9 Figure 4-90.  Measuring Heel Angle e. Care.    Observe  the  following  practices  for  the care and upkeep of drill bits: (1) Keep drill bits in proper storage to prevent sharp edges from striking each other. (2) Remove foreign material with a clean rag after use. (3) Apply a light coat of oil to prevent rust. 4-14.  Reamers.  A reamer is a cutting tool with one or more  cutting  surfaces  used  for  enlarging  to  size  and contour  a  previously  formed  hole.    A  reamer  functions by removing a small amount of stock from the walls of a hole.    To  ream  effectively,  the  diameter  of  a  reamer must be greater than the hole to be reamed. NOTE Do not use the reamer to remove more than 0.002 to 0.003 inches of metal.  If the  hole  is  too  small,  enlarge  it  with  a drill before reaming it. a. Description.      Figure   4-91   shows   the   parts   of several   types   of   reamers.      The   cutting   face   is   the leading  edge  in  the  direction  of  rotation.    Longitudinal channels (flutes)   in   the   body   of   the   reamer   are   used   for   the passage of lubricating fluid and chips. b. Types.        Reamers,    as    contained    within    the various  aviation  shop  sets,  conform  to  types,  classes and styles as specified in Federal Specification GGGR- 180.        Reamers    have    been    classified    according    to construction  and/or  method  of  holding.    Only  a  few  of the reamers listed in the Federal Specification are used in  Arm  aviation  shop  sets.    An  explanation  of  reamers found in aviation shop sets follows: (1) Adjustable,  inserted  blade,  straight  fluted (hand),  per  GGG-R-180,  type  111,  class  1,  grade  A. These reamers are fitted with removable cutting blades, which are adjustable for reaming holes of any size within the  range  for  which  the  reamer  was  designed.    These reamers  have  straight,  round  shanks  with  square  ends and  contain  slots  for  holding  the  blades.    The  reamer assembly   is   capable   of   reaming   round,   straight,   and smooth holes.  This reamer is shown in figure 4-92. (2) Jobbers (machine) reamer, perGGG- R180,  type  XII.    These  reamers  are  of  grade  A  high speed steel and have straight flutes and right hand cut, as  shown  in  figure  4-93.    The  cutting  section  of  these reamers  is  capable  of  cutting  straight,  round  holes  of specific    diameters.        These    reamers    are    normally provided as a set. (3) Brown  and  Sharpe  taper  socket  (hand), per   GGG-R-180,   type   XIV.      These   reamers   have   a fluted    type    section    and    straight    round    shank    with squared  ends.    The  cutting  section  of  these  reamers  is tapered for reaming Brown and Sharpe 1/2 inch per foot standard sockets.  The Brown and Sharpe taper is used for  tools  with  B  +  S  taper  shanks.    It  is  also  used  for threaded taper pins.  This type is shown in figure 4-94. (4) Repairman's T-handle (hand) reamer GGGR-180,   type   XIII.      These   reamers   have   straight flutes and a solid handle.  The cutting section tapers 1- 1/4 inches per foot, as shown in figure 4-95. c. Selection.      As   stated   in   paragraph   4-14,   the diameter    of    a    reamer    should    be    greater    than    the diameter of the hole to be reamed.  All reamers, except for  adjustable  reamers,  are  marked  with  their  nominal size. d. Use. The following paragraphs provide procedures   for   using   a   typical   reamer.      Proceed   as follows: 4-34