Orion SkyQuest XX12g Instruction Manual page 10

3. Next, assemble the telescope's rear end ring to the pri-
mary mirror cell. Find a clean, flat surface, and turn the
mirror cell over so that the mirror is facing downward. For
the XX14g, we recommend placing a soft towel on a flat
surface and placing the mirror face down on the towel,
because the aluminized outer edge of the mirror will
contact the surface. With the XX12g mirror, on the other
hand, the aluminized mirror itself will not make contact
with the surface; only the mirror retaining clips will.
Place the three springs onto the three exposed threaded
shafts (Figure 15a). Lower the end ring onto the mir-
ror cell so the threaded shafts pass through it, and the
end ring rests on the springs (Figure 15b). Add a nylon
washer to each collimation knob and thread the collima-
tion knobs through the end ring and onto the threaded
shafts (Figure 15c). Make sure the knobs have at least
three full turns of engagement on the shafts. The mirror
cell is now almost ready to be installed onto the lower
tube section.
4. Check to make sure that the three mirror retaining clips
are properly tensioned (XX12g only). If they are too tight,
the pinching of the mirror's edge will distort the images
you see through the telescope. But if they are too loose,
the mirror could shift or even fall out if it is tilted severely.
With the mirror in its cell facing up, use a Phillips screw-
driver to loosen the two screws on one of the clips until
you can easily move the small metal plate underneath
the screw heads. Then gradually tighten both screws just
until the metal plate is no longer loose. Repeat this with
the other two retaining clips. Now the clips are properly
tensioned.
5. Assembling the end ring (and mirror assembly) back onto
the tube can be a bit tricky. This is because the large
diameter and thin metal of the tube will cause the tube
to become somewhat out of round once the end ring is
removed. To assemble the rear end ring (with mirror and
mirror cell now connected) to the tube, stand the lower
section of the tube up vertically so the raw edge of the
tube is up. Line up the threaded holes in the edge of the
end ring with the holes in the end of the tube. Then, lower
the entire assembly onto the tube. (Be careful to avoid
finger pinching during this step!) There may be a bulge in
the perimeter of the tube that prevents the end ring from
fully seating onto the tube (Figure 16). Press against this
bulge, and the entire mirror cell assembly should seat
onto the tube. Now, replace the eight Phillips screws that
connect the rear end ring to the tube.
10
Spring
a.
b.
Collimation
knob
c.
Figure 15. a)
Place the three springs on the exposed threaded
b)
shafts of the mirror cell. Lower the rear end ring onto the mirror
cell so that the threaded shafts pass through the end ring, and the
end ring rests on the springs.
nylon washers attached, through the rear end ring and onto the
threaded shafts.
Figure 16.
Locate the area of tube that is bulging out and
preventing the end ring from fully seating. Press on this bulge to
allow the mirror cell to seat properly on the tube. Be careful not to
pinch fingers!
Shaft
Nylon
washer
c)
Thread the collimation knobs, with