Great Planes PT-60 Kit - GPMA0119 - Manual (Page 25)

HOW TO MAKE "SOFT WEIGHTS"
Weights are needed for a variety of purposes during the
model building process, especially when setting wing
washout or if you need an extra pair of hands We made
some 2 and 3 pound "soft weights" for use in our shop
as follows:
A. Obtain four small, but sturdy plastic bags (freezer
bags work w e l l ) , four old tube socks (preferably
laundered), and 10 pounds of buckshot, available at
sporting goods or gun stores Sand can also be used,
but the weights become pretty bulky.
B Use a scale to measure out two 2lb bags and two 3lb
bags of shot (or sand) Seal the bags with masking tape,
without compressing the contents Soft weights work
best if they are floppy like bean-bags.
D 2 Trim off the protruding end of the top spar to match
the angle of the slotted web as shown, or sand it flush with
80-grit sandpaper and a sanding block.
D 3 Follow the expert tip shown below to join three
3/32" x 2-3/4" x 36" balsa sheets together to make an
8-1/4" wide skin.
C Put the sealed bags into the tube socks, then tie a
knot in the socks to prevent them from leaking all over
your bench.
D 1 Use 6 minute epoxy to install the laminated center
rib R-1A on the centerline of the wing between the spar
joiner and the TE joiner.
After the epoxy has cured, use the hole you sanded in
the LE ends as a guide to drill through the ply LE joiner
with a 5/16" bit Test fit the dowel fully into the slot in the
R-1A rib assembly.
HOW TO MAKE A BALSA SKIN
A. True up the edges of the sheets with a metal
straightedge and a sharp knife or a long sanding block.
B. Test fit the sheets together to make sure they
match well.
C. METHOD "A": Edge glue the sheets together with
thin CA over a flat surface covered with waxed paper.
A quick wipe of the joint with a fresh paper towel will
remove excess glue and make sanding easier Mark
the poorest surface that you think should be the
inside of the sheet with an "I".
METHOD "B": Edge glue the sheets together with
Great Planes Pro Wood Glue Smear the glue lightly
along an edge with your finger, then join the sheets
over a flat (waxed paper covered) building board Pin
the sheets to the board to hold them together Wipe
off any excess glue before it dries Pro Wood Glue is
easier to sand and won't leave a ridge at each seam,
as CA is prone to do.
D. Place the skin on a large flat surface and sand it with
a large, flat sanding block and fresh, sharp 220-grit
sandpaper Use light pressure and a brisk
circular motion.
E. Trim the perimeter of the sheet to square things up
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