Figure 4-90. Measuring Heel Angle
Care. Observe the following practices for the
care and upkeep of drill bits:
Keep drill bits in proper storage to prevent
sharp edges from striking each other.
Remove foreign material with a clean rag
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.
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.
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
(flutes) in the body of the reamer are used for the
passage of lubricating fluid and chips.
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:
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.
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.
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.
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.
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
procedures for using a typical reamer. Proceed as