9
Assembling the NGT-12.5
Using the following steps, the NGT-12.5 can be easily assembled by one person. However, until you are comfortable
with the assembly steps, we recommend that you have another person on hand to help.
You can see photos
illustrating the assembly and disassembly procedures on our web site at jmitelescopes.com (select Pictures on the
NGT-12.5 page in the On-Line Catalog)
1.
Remove the primary mirror and cell from the tub (this step may be omitted for two-person setup).
2.
Place the base/split-ring/tub assembly on a flat surface in its intended location for use, using the supplied ground
pads if necessary. If the base is not level, you may adjust the leveling screws. For tracking purposes, point the
command center side of the base toward the equator and the opposite end toward the pole.
A quick-release feature allows the ring/tub assembly to be removed from the base by unscrewing the knob in the
polar axis (at the south bearing) and pulling the ring/tub assembly off the polar axis stud. When replacing the
ring/tub assembly, take special care in setting the ring down on the drive rollers. Be sure to detach the proper
cables before attempting to remove the ring/tub assembly
(see page 12).
3.
Place the primary mirror and cell back in the tub, orienting the mirror cell alignment studs over the corresponding
holes in the tub. Install the dust cover before continuing.
4.
Screw the three counterweights onto the bottom of the mirror cell beneath the tub. Be sure to tighten them
equally to assure correct positioning of the mirror cell.
5.
Tighten the right ascension and declination tension knobs.
6.
Three truss rod clips are located 120° apart around the rim of the tub. Each clip holds two rods. Any two
neighboring truss rods located in
adjacent
clips (not the same clip) make up a pair and are joined together at
their upper ends. The easiest way to insert the ball ends into the spring clips is by holding the opposing side of
the tub with the knee (to keep it from rocking), slightly opening the spring clip, then pressing the rod straight into
the clip by pushing down on the top end of the rod.
When ready to disassemble, the ball ends of the truss rods are easily removed by slightly pressing on the spring
clips while forcing the rods down toward the center of the tub. Placing a couple of fingers between a pari of rods
allows for removal of both at the same time without scratching the paint. Most of the work should be done by
leveraging the rods inward against the back of the spring clips rather than prying the spring clips open.
After inserting a pair of truss rods, align the holes at their upper ends. Next, insert one of the three thumbscrews
into the hole by pushing it from the outside toward the center of the telescope. When aligning the upper ends of
the rods, note that the flat plastic ends are offset to allow the rods to be properly placed in the same plane—the
offsets should be facing each other as shown on the
next page
. Repeat this procedure for the two remaining
truss rod pairs being consistent with right-over-left or left-over-right orientation for all three pairs.
Summary of Contents for NGT-12.5
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