Paper-Cutting Machines Part 8

87. What precaution is necessary in cutting printed sheets?

88. What is a mill edge and what does it require?

89. How can exact register and accurate tr.i.m.m.i.n.g be secured?

90. How may a pile be tested for squareness?

91. What device is used in cutting lithographed work and the like?

92. How can you cut stock in certain fixed portions?

93. What peculiarity have hand-made papers?

94. What precautions are needed with gummed and varnished stock?

95. What precaution is desirable in the cutting of freshly printed stock?

96. Give several methods of cutting a pile into strips of equal width.

97. How can you cut a pile rectangular?

98. What are the processes for squaring a pile?

99. How can you test a pile for squareness?

100. What care has to be used in cutting tissue paper?

101. How can waxed and oiled manifold stock be managed?

102. What additional margins should be left on book pages for tr.i.m.m.i.n.g after they are bound?

103. Describe the operation of tr.i.m.m.i.n.g books on a cutting machine.

104. How are quarter bound cut-flush pads or tablets trimmed?

105. How are blank books trimmed?

106. How are spring-back account books trimmed?

107. How are brochures with extended covers trimmed?

108. What should be done with cuttings and waste?

109. By what can you measure the worth of a paper-cutter operator?

110. How would you apply the test?

111. How can waste be prevented, or waste paper utilized?

112. Where does a paper-cutting machine naturally show special wear?

113. What other consideration affects the value of a machine?

114. How does the invention of improved machines affect the value of old-style machines?

115. How long should a good paper cutter last?

GLOSSARY OF TERMS USED

AUTOMATIC CLAMPING--Means that the clamp descends upon any height pile and produces approximately the same clamping pressure for all heights and all kinds of material. Among the methods for producing this pressure for automatic clamping are devices which employ friction discs turned only one way by ratchets which produce the maximum pressure with the least expenditure of power; friction discs or friction plungers worked forward and reverse; surfaces sometimes combined with wedge-shaped ways for producing a resultant pressure from the knife; weights, oil and hydraulic and air plungers; springs, climbing gears and weights, etc.

BACK GAGE--A movable device against which the paper is placed for measuring the size of the sheet to be cut.

BRAKE, AUTOMATIC FRICTION--Generally a band with a lining which grips automatically the outside of a wheel fastened to the driving gear and stops it promptly after every cut when the knife rises to the top.

CHUG--The action of the knife that results from lost motion in the parts connecting the knife-bar to the parts that operate it. "Chug" is caused, first, by the looseness of fitting necessary to permit the parts to operate without heating, and second, by wear of these parts.

"Chug" dulls knives and spoils stock and makes expense for grinding, sharpening, and knife replacement.

CLAMP--The part that presses the work firmly on the table to hold it while being cut.

CLAMP, ONE PIECE--Means a single casting used both for marking (or gaging) the stock where the knife is going to cut and also for pressing the pile to hold it.

CLAMP DWELL, LONG--Means that the clamp is held down a little longer upon the pile after the knife has cut, so as to allow the knife to rise to a safe height before the clamp is released. This prevents the knife rippling up the sheets on the return motion and disturbing the pile.

CLAMP FACE--A removable flat steel plate fastened underneath across the clamp fingers to prevent the indenting of soft stock.

CLAMPING, AUTOMATIC PRESSURE ADJUSTMENT--A device for varying the holding pressure easily and instantly for different kinds of work.

CLUTCH, FRICTION DRIVING--An improvement over the jaw clutch, because instead of starting the machine with a jar, it permits gradual engagement of the power.

COUNTERBALANCE WEIGHT FOR KNIFE-BAR--A safety device which, through constant and dependable action of gravity, always tends to keep the knife from dropping.

CUTTING STICKS--A wood or soft metal piece inserted in the table, on which the knife edge strikes; in shape usually square, but sometimes round and rotatable by hand or power to present fresh surfaces after a number of cuts.

DOUBLE-SHEAR STROKE--Means there are three motions taking place at the same time; first, the downward motion through the pile; second, the single "shear" motion across the face of the pile; and third, the double-shear motion which means that the cutting edge starts to cut higher at one side than the other and by rocking approximates parallel when it reaches the bottom of the cut at the table. The double-shear cuts more like a pair of scissors, the knife edge entering each sheet at its side and gradually cutting across it. Its advantages are less power required to cut, less strain on the machine and the knife, a more perfectly cut edge and a smoother face to the pile. See Fig. 10, Page 18.

DUPLICATING DEVICES, AUTOMATIC--See "s.p.a.cing Devices."

GAGE MOVEMENT, CABLE--A steel wire cable wound around a drum which when revolved pulls the back gage forward or backward.

GAGE MOVEMENT, CHAIN--A connection for operating the back gage to and fro; princ.i.p.ally used with automatic s.p.a.cing devices.

GAGE MOVEMENT, POWER--A friction drive variable speed connection from the main driving shaft to move the back gage forward and backward.

GAGE MOVEMENT, SCREW AND HAND WHEEL--This is used on the simpler, cheaper styles of cutting machine devices. It is slower than the cable device, but more reliable.