|
|
Buffing
and polishing using wheels and 'compounds' is somewhat like using wet and dry
sanding paper, only much faster. Instead of using 'elbow grease' you will be
using the power and speed of an electric motor.
The edge, or face, of the wheel is the 'sanding block', which carries a thin
layer of 'compound' which is the sandpaper. Varying types of wheel are
available, and the different grades of compound are scaled similar to sandpaper.
The compounds are made from a wax substance which has the different abrasive
powders added to it. When this hard block is applied to the edge of a spinning
buffing wheel, the heat from the friction melts the wax, and both wax and
abrasive are applied in a thin slick to the face of the wheel.
The objective of buffing and polishing is to make a rough surface into a smooth
one and, of course, each work piece will be in a different condition, so will
need different procedures. Imagine the surface magnified thousands of times, it
will look like jagged mountains and valleys. By repeated abrasion, you are going
to wear down those mountains until they are old, soft, rolling hills! Then they
will not dissipate the light, but reflect it. It is the reflection that makes
the buffed part appear shiny.
TRICKS OF THE TRADE
Repairing small dents
Sand the inside of the part with
emery paper.
This will show you exactly where the dent is. Using a piece of end grain wood as
a block, gently beat out the dent with a hammer.
Clean your buffing wheels with a
WHEEL RAKE
Offer the jagged blade to the edge of the spinning
wheel,
and work it across the face until the
wheel
looks bright and fluffy once more. This action, done periodically, will remove
entrapped metal particles, which could scratch a more delicate part.
Eliminating 'Swirl' Marks
Swirl marks caused by buffing in the final stages can easily be removed by
wetting the part with a damp cloth, then dusting with a powder such as:-
Whiting, Talcum Powder or Corn Starch, then buff on your wheel again until the
swirls disappear.
One Wheel For One Compound
Applying different
compounds
to the same
wheel
only causes problems, because you end up with a mixture of abrasive surfaces,
and metal deposits left over from the more abrasive operation. These microscopic
particles only scratch the surface, destroying any benefit gained by the finer
compound. To remove excess compound from the work, apply a small amount of talc
to the work and the
wheel,
then rebuff.
Applying Compound
LITTLE & OFTEN is the rule. Too much
compound
will reduce the effectiveness of the cutting action, because the surface will
become TOO greasy and over lubricated. This can often be seen by the prescence
of a black slick of
compound
that seems to reveal around the work piece. Apply
compound
to the wheel for approx 1 second. Any more is wasted.
CHOOSING THE RIGHT WHEEL
There are different types of
wheels
and these have different effects on the
compound
they are used with. For example, the
SISAL
wheel is a coarse 'rope like' fiber, which frays out to make a sort of brush.
These fibers have a very beneficial effect on scratched and rougher surfaces,
almost stroking them smooth. When used with a course 'EMERY'
compound,
they 'cut' the metal down very rapidly. You could use this compound on a
SPIRAL SEWN
wheel and it would work, but the job would take much longer because the softer
SPIRAL SEWN
wheel is not going to thrash the metal so aggressively.
As you progress through the buffing
compounds,
you will change your buffing
wheel,
ending up using a soft polishing wheel,such as the
CANTON FLANNEL
with the least abrasive
BLUE or RED compound
which only polishes, it has no cutting action.
So, depending on the job in hand, you will determine which abrasive
compound
and
wheel
you are going to use first, then step down through the stages until YOU are
satisfied with the results.
Compounds
are made from a mixture of fine abrasive fillers and a sort of greasy wax. The
compound is melted, by friction heat, as the bar is pressed to the revolving
wheel. This applies a thin layer of abrasive, 'glued' onto the cloth wheel,
making it similar to an emery paper, only much faster!
Do not apply the
compound
after the workpiece, or on its own. This wastes material and is much less
efficient.
By applying the material before the workpiece, you actually use the workpiece to
force the compound into the buff. This is much less wasteful, more efficient and
will actually speed up your buffing times.
CUT AND POLISH MOTIONS
There are two basic buffing motions you should use.
BUFFING SPEED AND PRESSURE
The correct pressure must be applied to the work piece to provide the best finish
economically and safely. Inadequate pressure will give NO buffing action.
Excessive pressure will cause the buffing wheel to slow down or actually
collapse. This can also result in burn marks on the work piece.
BUFF RUNNING SPEEDS
For best results your wheel should maintain a surface speed of between 3600 &
7500 Surface Feet Per Minute. (SFPM). The higher your speed, the better and
quicker your results.
WHICH WHEEL & COMPOUND?
Use this chart to determine which wheels and compounds to use to polish
different metals. This is a guide...experienced polishers will vary the
materials used to suit the application and their technique. This chart serves as
a good starting point for beginning polishers, but feel free to experiment.
BLACK = Emery Compound, a course abrasive material for removal of scratches,
pits, paint,
BLACK = Emery Compound, a course abrasive material for removal of scratches,
pits, paint,
THE THREE BUFFING STAGES
|