Jet Tools 22-44 Plus - Manual (Page 14)

14
Selecting Abrasive Grits
The amount of stock to be removed is a major
consideration when choosing the grit grade to
start with. Grits of 24, 36, 50, 60 and 80 are
primarily designed for stock removal. Grits 24
and 36 will remove the most material in one
pass, whether you are doing abrasive planning,
cleaning up glued panels, or flattening stock.
Grits from 100 through 220 are primarily
finishing grits designed to remove the scratch
pattern from the previous grit used. For best
results, never skip more than one grit grade
when progressing through a sanding sequence.
For fine work, such as furniture, try not to skip
any grit grades during the sanding process. In
general, premium quality abrasives such as
genuine Performax abrasives will produce a
better finish with a less noticeable scratch
pattern. Note: Grits that are too fine can
sometimes burnish the wood and leave a glossy
surface that will not accept stains evenly. This
will vary by type of wood. Oak, for example, is
susceptible to burnishing because of its open
pores.
Stock Feeding Angle
The optimum stock feeding angle, when
sanding, is at a 60 degree angle (Fig. 13).
However, even a slight stock feeding angle will
provide more effective stock removal, less
loading of abrasives, longer abrasive life,
potentially faster feed rates and reduced motor
loads.
When finish sanding the workpiece should be
fed through in line with the grain on the final one
or two passes for the optimum finish.
Multiple-Piece Sanding Runs
When abrasive planing (or thickness sanding) a
run of similar pieces that you want to have the
same thickness, it is best to sand all the pieces
at the same time. This way you will be able to
determine the thickness of the thinnest piece
and process all pieces to that same thickness.
Be aware that the sander will remove cups and
crowns in the work piece; consider this when
measuring the processing stock to the same
thickness.
Edge Sanding
When edge sanding, the Performax sander will
mimic the opposite edge of the stock which is
lying on the conveyor belt. Because of this, it is
important for the stock edge to have been ripped
at the proper angle to the face before the
sanding process. When edge sanding stock that
is less than 3/4” wide, or more than 2” high, it is
good procedure to stack and clamp several
pieces together to prevent them from slipping, or
tipping.
Sanding Imperfect Stock
When sanding stock with a cup or crown, place
the crown up. This will stabilize the stock to help
prevent tipping or rocking during sanding. (After
the crown has been removed and the top is flat,
turn the stock over and sand the opposite side.)
To avoid personal injury, take special care when
sanding stock that is twisted, bowed or
otherwise varies in thickness from end to end. If
possible, support such stock as it is being
sanded to keep it from slipping, or tipping. Use
extra roller stands, help from another person, or
hand pressure on the stock to minimize
potentially hazardous situations.
Face Frames and Raised Panel Doors
It is very important to have the proper abrasive
contact when doing this type of sanding. If the
sander is set to take an excessive depth of cut,
the result can be a gouge, or dip as the drum
goes from sanding the rails at full width to
sanding just a few inches of width on the stiles.
To prevent this problem, make sure that when
using abrasives finer then 80 grit the drum is in
contact with the wood, but can still be spun by
hand.
Monthly Maintenance
For best results, perform the following
recommended maintenance procedures on a
monthly basis:
•
Lubricate conveyor bushings and check for
wear.
• Lubricate all moving parts, such as threaded
rods, washers, and bushings.
• Clean sawdust from the conveyor belt and
sandpaper.
•
Blow dust from motors and switches. Blow
dust from the inside of sanding drum to
prevent vibration. Be careful not to disturb
the drum balancing weights.
•
Check all setscrews for tightness on parts
such as bearings, conveyor and couplings.