Blastrac 1-8DECMKI, Operating Manual

Page: 27 / 54

Operating Instructions 1-8DEC 230V
Setting the Correct Blast Pattern
5.1 Setting the Correct Blast Pattern
Setting the correct blast pattern is essential before an even, clean profile can be
achieved when shotblasting with a Blastrac machine. An uneven blast pattern can
leave shadows on either side of the floor surface and can cause premature wear to the
internal components. The importance of setting the proper blast pattern cannot be
overstressed.
There are four major factors that can affect the blast pattern. They are:
1. Wheel Rotation - The blast wheel must be rotating in the proper direction indicated
on the housing that surrounds the blast wheel. Most Blastrac machines rotate in a
counter-clockwise direction when looking at the machine
from the operator’s
position.
2. Worn Wheel Kits - Wheel kit components such as blades, impellers and control
cages vary in different machines but perform similar functions. These kits must be
periodically replaced to ensure that they provide the proper blast pattern and to
eliminate excessive wear which can cause internal component and bearing unit
damage.
3. Abrasive Size - The size of the abrasive can affect the blast pattern. Different sized
abrasives have different mass characteristics that can alter the
“hot spot” setting.
See Figure B.
4. Control Cage Setting -The setting of the control cage
is the most critical factor in determining where the
blast pattern is directed. Ideally, the blast pattern is
centered so that the area being cleaned receives
a consistent, even distribution of high velocity
abrasive. Altering the setting of the control cage can
move the blast pattern to the left or right depending
on which direction the control cage is moved.
Moving the control cage too far in either direction will
direct the abrasive blast pattern to the side of the
machine and cause premature wear to the internal
components. The exact positioning of the control
cage is done by trial and error. The initial setting of
a machine rotating in a counter-clockwise direction
26