Paasche Airbrush AB-PL - Manual (Page 2)

Page 2 Paasche AB (Fine Art) Airbrush Instructions and Parts List
BASIC PRECAUTIONS:
Before starting any adjustments or parts replacements,
a couple of precautions should be observed. The fine tip of
the needle is very delicate, and once damaged it is difficult
to straighten again. Remove the needle before beginning a
repair, or if necessary use an old needle. Secondly, most
of the threaded parts are made of brass, and the threads
are easily stripped. Do not force the parts to do what they
don’t want to do.
(See section “Speed Regulator Screw” for specific
example of this problem.)
ADJUSTING STIPPLE ADJUSTER & AIRBLAST JET:
The stipple adjuster is the screw at the elbow of the
airblast tube. It controls the airflow through the airblast
tube. By turning this screw in (clockwise), you restrict the
volume of air blown out the airblast jet and across the
needle. When the air is almost shut off you create a grainy,
stippling effect.
The threads of the stipple screw can become so loose
that it will not hold its position in the airblast tube and will
gradually turn out as you use the airbrush. As a preventive
measure, we suggest you avoid excessive turning in and
out of this screw. From the fully closed position, you only
need to turn the screw two full turns to fully open this little
valve.
If the screw is too loose, you can tighten the threads’ fit
by pressing a dab of beeswax onto the threads and rolling
the screw between your thumb and forefinger to work the
beeswax into the threads. Only a thin coating is needed.
Then pass the screw very briefly over a match flame,
melting the beeswax into the threads. The wax will adhere
better as you insert the screw back into the airblast tube.
SPEED REGULATOR SCREW:
This screw works much the same as the stipple
adjuster. It controls airflow and thus the speed of the
power wheel and the needle. Again, all the adjustments
happen within a range of two turns of the screw. As noted
before, do not try to force the screw tighter than it wants to
go. You can shear the head of the screw right off, leaving
the screw firmly embedded in the body of the airbrush,
impossible to remove.
POWER WHEEL TOP SHAFT BEARING ADJUSTING:
Adjusting shaft bearings is a procedure that should be
done only if the power wheel is sluggish, is intermittently
binding, or is completely stuck. To check this, remove the
needle, then try to operate the power wheel and walking
arm, pressing down the finger lever and moving it back
and forth. If the power wheel runs smoothly now, the
problem is with your needle, not with the bearing
adjustments. If the problem continues, however, you will
need to adjust the bearings. If the power wheel is sluggish
or will not move at all, it could be that you simply need to
loosen the top bearing a little. Remove the top grease cap,
exposing the top shaft bearing. You will find the bearing
covered with grease, which you may want to remove in
order to see the slot in the top of the bearing better. To
adjust the bearing, use a screwdriver with a blade as wide
as the opening into which the bearing fits. A larger
screwdriver can be filed down to fit exactly the slot in the
bearing. While pressing down on the finger lever for air,
slowly loosen the top bearing (turn counter-clockwise). If
the power wheel frees itself and begins to run smoothly,
you have found the problem. To adjust the bearing
accurately, tighten it again until the power wheel stops,
then loosen it just until the power wheel runs smoothly.
This is a matter of 1/16 to 1/8 turn, never more than 1/4
turn. Do not loosen the bearing beyond the point where the
power wheel frees itself and runs smoothly. Beyond this
point the power wheel will begin to vibrate in the bearing. It
will appear to be running smoothly but then will suddenly
bog down. If this happens, tighten the bearing a little. You
will find the power wheel returns to normal speed.
If you find that the power wheel runs smoothly for a
while then freezes up again, the problem is that the
threads in the power wheel cover have become too worn
to hold the bearing snugly in place. The power wheel
happens to spin in the same direction needed to tighten
the top shaft bearing. If the bearing does not fit snugly in
the power wheel cover, the power wheel will actually drag
the bearing until it stops the power wheel! The remedy for
this situation is the same as for the loose stipple adjuster
or speed control—work beeswax into the threads of the
bearing. Over a long time period, the beeswax will wear
out and this repair will have to be done again.
FINGER LEVER ADJUSTING SCREW:
This screw is located at the back of the finger lever, in
the lever fork, and adjusts the “rest position” of the finger
lever. When you turn the adjusting screw in, the walking
arm is pushed farther into the stream of air from the
airblast jet. By adjusting this screw you set the width of the
line created when the finger lever is simply depressed, but
not pulled back (the “rest position” spray width.) Note: In
the “farthest forward rest position” you get no spray if the
color cup is properly positioned.
Be careful with the two extremes of this adjustment. If
you turn the adjusting screw too far out (counter-
clockwise), the needle moves to the very end of the slot in
the walking arm, and the needle binds between this slot
and the slot in the color cup support. Always check that the
needle is at least a “hair’s breadth” from the very end of
the walking arm slot.
On some ABs, if you turn the adjusting screw too far in
(clockwise), the walking arm will be pushed too far forward
and will hit the front of the opening in the power wheel
cover through which it extends.
SHAPING THE NEEDLE:
In general an AB needle should be curved in two
directions. Viewed from the side the needle should have a
slight arch, so that the needle guide can hold it firmly in the
slot in the needle bearing. Viewed from the top, the needle
should curve underneath the lip of the needle guide screw.
Both arch and curve should be gradual bends along the
length of the needle, with no sudden bends or angles.
About 3/8 inch at the tip of the needle—that portion which
rides in and out of the needle bearing—should be left
straight. In fact, try not to touch the tip at all as you are
arching and curving the needle, for fear of distorting the
needle. Remember that you are shaping the needle to fit
your particular airbrush.
The arch (side view) of the needle does not need to be
too great—just enough to give a little tension when the
needle guide is screwed all the way down. With a more
extreme arch the tip of the needle rides in the bearing at
too great an angle. In addition, the motion of the needle is
not as smooth, because the crest of the arch is passing in
and out from under the needle guide.
Continued on page 3