Machine Operation
www.nationalequipment.com
Phone: 763-315-5300
18
SHEAR POINT
The shear point is the point where material to be removed will cut cleanly from the
fl
oor. If
the blade is too wide, too dull, or too steep, the shear point is lost.
WEIGHT VS. SHARPNESS
The most common way to compensate for a dull blade is to add more weight and raise
the blade angle (see high setting). Weight allows dull blades to be used to a point.
Weight also causes blades to dull and break easier. Blades of any thickness tend to
catch cracks and expansion joints and will bend or break the blade if set at a high angle.
For best results, run a small ditching blade at a low angle to identify as many cracks and
joints as possible. If blades are breaking, you are misunderstanding the conditions.
CUTTING HEAD ANGLE
Set the cutting head angle to where the material comes up the easiest. Start with a lower
angle setting and raise slightly as the blade wears to maximize the shear point.
STEEP CUTTING HEAD ANGLE
A steep angle is only used for re-scraping. The slide plate has to be raised so the bottom
of the slide plate is higher or even with the bottom of the guide channels (Figure X). Rais-
ing the slide plate to an angle too steep when operating will cause the machine to jump
and buck. It does not give the operator a clear vision of the cutting head and it raises
the machine to operate at a unsafe operating height (Figure Y). Failure to raise the slide
plate could cause machine damage and/or bodily injury.
SWIVEL HEAD
The swivel head keeps the blade in contact with the
fl
oor even when the
fl
oor is uneven.
When using a
fl
at blade, turning the head over 180° allows another sharp edge on the
blade without having to replace the blade.
CUTTING HEAD INSERTION
With machine off, insert desired cutting head into cutting head holder. Secure with cutting
head clip.
SAVING TIME WITH EXTRA CUTTING HEADS
Having additional cutting heads will save time on the job. Insert blades into the extra
cutting heads before starting a job. When the blade is dull, instead of taking the time to
replace it or sharpen it on the job, remove the cutting head and replace it with another.
In some isntances a different type or size of blade is needed. Installing the other size or
type of blade in a seperate cutting head limits operation down time.
FIG. X
FIG. Y
Slide Plate is not raised
