IBM Selectric Reference Manual

7.
d. Hand-cycle the machine until the print cam follower
i'~ at the low point of the cam. This may not be at
the resf position. The low point of the cam can be
determined by observing the movement of the head
toward the front of the machine. With the type head
at its most forward point, adju5,t the velocity control
plate pin forward or back in the cam follower slot
until a clearance of .260" to .270" exists between
the center of a zero rotate, zero til t character and
the platen (Fig. 140).
Since this .260" to .270" is measured between the
type head and the platen it is not a measurement of
the powered trave I of the typehead. The .020" to
.030" free flight is included in this .260" to .270"
and must be subtracted in order to determine the
amount of powered travel. The powered travel must
never exceed .265" as this wi II cause typehead
breakage.
The base of the Hooverometer handle can be used
as a measuri ng
devi ce as illustrated in Fig. 140. The
handle base is about. 250
11
thick; however they do
not
all measure the same. Each handle should be
measured
with a dial indicator or micrometer to
determine its exact size. When the size of the
handle base is determined, a thickness of tab cards
should be placed around the platen that will total
.260" to .270" when added to the thickness of the
handle base.
e. Both adjustments must be rechecked and refined unti I
these conditions are obtained. Be sure to tighten
both screws firmly when the adjustments are com-
pleted.
NOTE: The adjustments should be checked with
the ri bbon removed.
These adjustments are designed to produce optimum
print
quality for most applications; however, a cer-
tain amount of variation in velocity is permissible in
orderto satisfy a customer1s appl i cation. Be cautious
of creating an excessive increase or reduction in
velocityas this will adversely affect the uniformity
of impression between characters and the general
appearance of the printed copy.
Anvi I .. The eccentric at each end of the anvi I is ad-
justed so that the anvil properly restricts the free flight
of the typchead. The adjustment can be checked by
typing a period with the copy control lever set all the
way back. The period should fai I to print or print very
faintly. With the copy control lever pulled forward one
notch (fourth position), the period should print lightly.
The ribbon and one sheet of paper should be used when
making the check • The check should be made at each
end ofthe platen only, because flexing of the parts wi II
allow a slightly different condition in the middle of the
platen. The high part of each eccentric should be kept
to the rear.
NOTE: The restoring cam follower eccentric shoul.d be
adjusted all the way up while the anvil is being set. On
15 inch machines the carrier buffers must also be moved
up out of the way of the anvil (Fig., 141).
8.
9.
2-45
FI GURE 141. Carrier Buffers (15 Inch Machines)
The free fl i ght must be restri cted to insure that the char-
acters will all emboss the paper to the same depth. If
no restriction were appl ied, the smaller characters such
as punctuation marks would be allowed to emboss too
deepl y. The surface area somewhat restri cts the amount
of embossing for the larger characters; thus if the free
fl ight of the rocker is stopped at the right point I even
impression between all characters will result.
CAUTION: Raising or lowering either end of the anvil
will slightly affect the adjustment at the other end. Be
sure to recheck each adjustment. A clearance of .010"
to .045
11
must be maintained between the left anvil
bracket and the sideframe for noise reduction purposes.
Adjust
the bracket left or right on the anvil to obtain
the clearance (11 inch onl y).
Carrier Buffers (15 Inch Machines) - A buffer plate at-
tached to the right side of the carrier and an adjusting
screw under the left side strike the top of the anvil to
prevent the print shaft from flexing downward. Each
should
have .002
11
to .004" clearance with the top of
the anvil (Fig. 14l).
Print Cam Follower
a. Pri nt Cam Follower Stud - Adjustthe pivot stud left
or right so that the rubber roller on the follower is
centered on the surface of the restoring cam. The
stud is held in place in the carrier b.y a set screw
that is accessible from the bottom of the machine_
b. Restoring Cam Follower Eccentric - With the print

IBM Selectric Specifications

General

Type	Electric typewriter
Introduced	1961
Keyboard Layout	QWERTY
Carriage Return	Electric
Manufacturer	IBM
Printing Technology	Typeball (golf ball)
Power Source	AC Power
Power Supply	120V AC