Orion SkyQuest XX12g Instruction Manual page 12

8. Attach the upper tube section to the four truss connec-
tors at the top of the poles. Orient the upper tube section
as shown in Figure 19. Hold the upper tube section with
one hand while threading the knobs in the truss connec-
tors into the holes in the upper truss support ring. If nec-
essary, you can slightly adjust the position of the truss
connector with respect to the pole ends in order to have
the knobs and holes line up (Figure 20). When tightened,
the knob will clamp the truss connector against the regis-
tration flats on the upper truss support ring (Figure 21).
Repeat this for the other three truss connectors. Firmly
tighten the knobs.
9. Now go back and firmly tighten the eight clamping knobs
on the lower truss support ring.
If, after assembling, the truss poles are loose within the truss
connectors, use the supplied 4mm hex key to tighten the but-
ton head cap screws that connect the poles to the truss con-
nectors (see Figure 20). This should rarely need to be done.
The telescope is now assembled and ready to be mounted on
the Dobsonian base.
Mounting the Optical Tube on the
Dobsonian Base
As mentioned in the section above, there are two ways you
can mount the optical tube on the base: you can mount just
the lower tube section before assembling the entire optical
tube, or you can assemble the optical tube completely, then
lift it onto the base.
Mounting the Lower Tube Section (Only) on the Base
1. The left altitude hub on the optical tube has a dovetail slot
that slides into the altitude axis trunnion on the inside of
the left side panel (Figure 22). We recommend orienting
the trunnion such that the threaded hole for the tube con-
necting knob is facing upward. Then the telescope tube
can be held horizontally and just lowered into the base by
gently sliding the tube's altitude hub into the altitude trun-
nion on the base (Figure 23). If the altitude axis trunnion
on the base is oriented differently, you'll have to adjust
the angle of the telescope tube so the altitude hub slides
into the altitude axis trunnion. (The altitude axis trunnion
may be too difficult to rotate by hand to adjust its orienta-
tion.) Once seated in the base, the tube will freely rotate
to a vertical position due to its bottom-heavy imbalance.
That's OK. The tube should now be resting in a vertical
position in the base (Figure 24).
2. Now insert and tighten the tube connecting knob to
secure the tube in place (Figure 25).
3. For the XX14g, before assembling the rest of the opti-
cal tube, it is recommended that you install the counter-
weights on the rear cell so that the tube, when assem-
bled, will be properly balanced rather than front-heavy.
(The XX12g does not utilize counterweights.) There are
six counterweight disks, each weighing 2.2 lbs. Tilt the
12
Left side
bearing
Figure 19.
The upper tube section should be oriented relative to
the lower tube section as shown. Note the orientation of the focuser
on the upper tube section relative to the left side bearing on the
lower tube section.
Truss
connector
Truss
poles
a.
Figure 20.
The position of the truss connectors relative to the
pole ends can be adjusted to register the truss connectors with the
upper truss support ring.
lower tube section as needed to access the rear cell, and
while holding it up, thread two counterweights onto each
of the three counterweight mounting bolts.
Now you're ready to assemble the rest of the optical tube.
Refer to step 6 in the previous section, "Initial Assembly of the
Optical Tube."
Focuser
Button head cap screw
b.