User Manual
Undoubtedly, you have an airplane on which you are anxious to test
your C.G. Machine, so let’s get started!
TOOLS AND SUPPLIES REQUIRED FOR ASSEMBLY:
Thick or medium CA
Hobby knife
Phillips screwdriver
Small metal file
Thread locking compound
600 & 220-grit sandpaper
Small 90° triangle
Tissue or paper towel
Rubbing alcohol or glass cleaner
C.G. MACHINE PARTS
❏ 1. Examine all molded plastic parts, and trim off any mold flashing
with a sharp hobby knife. Examine the ends of the metal rods for
burrs, and carefully remove them with a metal file or emery cloth.
ASSEMBLY SEQUENCE
❏ 2. Insert the two 3/16" x 12" steel base joiner rods into the holes
in one of the molded plastic bases. Both of the bases are the same
so there is not a
right
or a
left
. The joiner rods should fit snug, but if
they are too tight, lightly lubricate them with bar soap. If the rods are
still too tight, carefully enlarge the holes in the base with a 3/16" drill
bit or a round file.
❏ 3. Join the other base to the joiner rods the same way.
❏ 4. Thread the two 2-56 threaded steel pivot balls into the ends of
the 1/4" steel upright rods with a drop of thread locking compound.
Carefully remove any burrs on the pivot balls with a small file. Clean
the pivot balls with a tissue.
❏ 5. Push the 1/4" steel upright rods all the way into the bases. If
there is much resistance, carefully enlarge the holes with a 1/4" drill
bit or a round file.
❏ 6. The plastic ruler set consists of two rulers, connected
by three
tabs. Use a hobby knife to cut part-way through each tab on both
sides of the rulers, then carefully flex and snap the rulers apart. Trim
the remaining tabs flush with the edge of the rulers,
then finish with a
flat sanding block and 220-grit or finer sandpaper.
❏ 7. Insert the .074" x 2-1/2" wire pointers into the plastic ruler end
caps. This should be a secure friction fit.
❏ 8. Slide the ruler end caps onto the rulers. When the ruler end caps
are fully seated, the pointers should be perpendicular to the ruler – you
can use a small 90° triangle to check. If it is necessary to adjust the
fit, sand the end of the ruler slightly or trim the slot in the ruler end cap.
❏ 9. Apply a drop of thick or medium CA to both sides of the ruler at
the “zero” end, insert the ruler fully into the slot in the end cap, then
immediately confirm that the pointer wire is vertical. Attach a ruler end
cap to each of the rulers.
❏ 10. Check the fit of the rulers in the molded plastic ruler holders.
The rulers should slide freely in the ruler holders. If they do not,
carefully sand the edges of the rulers with a sanding block and fine
sandpaper until the rulers slide freely.
❏ 11. Loosely attach the ruler holder to the molded plastic socket cap
with a #4 x 3/8" screw.
❏ 12. Insert the ruler through the ruler holder, then tighten the screw
only enough to provide friction. Do not overtighten the screw, as this
may deform the plastic.
❏ 13. Clean the top of the socket caps with a tissue or paper towel
dampened with rubbing alcohol or glass cleaner. Peel off the backing
from the foam rubber pads, then apply the pads to the tops of the
socket caps.
❏ 14. Snap the socket caps onto the steel balls on the upright rods.
There is not a front or a rear to the C.G.Machine so at this time it does
not matter onto which upright rod you install the socket caps.
❏ 15. Pivot the socket caps throughout their range of motion to check
for free movement. If there is a significant amount of friction between
the cap and the ball, remove the cap and snap it on again, moving
and spinning it around. If there is still too much friction, polish the steel
ball with 600-grit sandpaper and coat it with a thin film of bar soap.
❏ 16. Apply the peel-and-stick decal to the top edge of one of
the bases.
C.G. MACHINE
™
ASSEMBLY INSTRUCTIONS
Thank you for purchasing the Great Planes
®
C.G. Machine. We are
glad you realize the importance of properly balancing your model
and the effects the C.G. location has on the way it flies. Although
checking the C.G. is often one of those last minute “oh, I’d better do
that before I get to the flying field” procedures, the C.G. location can
have a profound effect on the way all models handle and respond to
control inputs.Therefore, determining and shifting your model’s C.G.
is an operation that you should perform with care and accuracy.
That’s where the Great Planes C.G. Machine comes into play. With
the Great Planes C.G. Machine, you can accurately and easily
balance your model according to the manufacturer’s recommendations,
and then make incremental changes to the C.G. location to alter your
model’s flight characteristics according to your flight skills
and preferences.
Great Planes Model Manufacturing
P.O. Box 788
Urbana, Illinois 61801
(217) 398-8970
Entire Contents © Copyright 2004 BALP01 v1.1
Not designed for
use with planes
under 2 lbs
flying weight.