4. Tighten the remaining bolts that hold the knife
lever placed at the center of the blade and
in place.
tighten the center bolt. Continue prying and
tighten from the center to the right bolts and
5. Lower the ram again and recheck the knife
from the center to the left bolts until the knife
clearances. Make additional adjustments if you do not
is secure.
get a reading of 0.010 inch at the first and last
holddowns and 0.008 inch in the center. As a rule of
Repeat the above step for the lower knife.
thumb, the center measurement should be 0.002 inch
less than the end measurements to allow for flexing of
Knife Clearance.--After the knives has been
the knives during shearing.
installed, you must set the proper clearance (fig. 13-22)
between the upper and lower knives. This is the most
Universal Ironworker
important adjustment on most drop shears. Unlike a
pair of regular handheld shears that have the blades
The universal ironworker performs many of the
scraping next to each other during the cutting stroke, the
basic machine operations in the shipfitter shop. It is best
knives on the drop shear have a clearance between the
used for performing identical operations on many
two knives to prevent binding during the shearing
pieces of standard metal stock. The universal
stroke. If the knives are set too close, the shear will bind
ironworker is capable of several operations, including
and cause damage to the machine. If the blades are set
punching, stock cutting, notching, and coping.
too far apart, the plate will be sheared with rough edges
and burrs. If the knives have excessive clearance, thin
There are two basic types of ironworkers used in
plate may even be bent between the knife edges, causing
the Navy: the old mechanical driven type, as shown in
binding. The following procedure should be used to set
figure 13-23, and the newer hydraulic version, as shown
knife clearance:
in figure 13-24. In this section, we will discuss safety
1. Select the proper knife clearance for the metal
associated with the universal ironworker and the
punching, stock cutting, and coping evolutions.
type and thickness being sheared. (Always refer to the
manufacturer's technical manual when selecting knife
clearance.) Most drop shears in shipfitter shops are
UNIVERSAL IRONWORKER SAFETY.--As
adjusted with a side clearance of 0.010 inch at the edge
with the shear, safety should be of great concern. The
dogs and 0.008 inch in the center, which is satisfactory
ironworker is a very dangerous piece of equipment to
for general shearing requirements.
operate due to the force required to work thick metal.
2. Rotate the flywheel by hand until the knives
A special safety concern for the ironworker is the
cross the first holddown and the clearance of 0.010 inch
operation of several different stations from one foot
is reached using a feeler gauge.
pedal or trip lever. The following is a list of some of the
3. Slowly lower the ram until the knives cross at
more common safety precautions:
the last holddown, adjusting to 0.010 inch at each
--Become familiar with the type of ironworker
holddown.
installed in your shop. Prior to operating the machine,
qualify on its use and operation under qualified
supervision.
--Determine the capacity of the machine being
used from the manufacturer's technical manual and
never exceed its maximum capacity. Capacities for
most machines are given in metal thickness, length, and,
unless otherwise noted, are given for mild steel not alloy
steels. As metal hardness increases, machine capacity
decreases.
--Stay alert! Never insert hands between tooling
for any reason, keep them out of strippers and
holddowns.
--Properly align and tighten all tooling. Check
Figure 13-22.--Drop shear knife clearance.
clearance before proceeding.
13-22
