The CI700 Clutches
There are 2 types of clutches in the CI700:
- engage/disengage the scope from the R/A and DEC shafts, allowing the
scope to be swung by hand.
- engage/disengage the motors from the worm shafts, allowing the worm
shafts to be turned (slow-motion controls).
factory form both clutch types are prone to a certain amount of
slippage. Also, if the CI700 clutches are tightened too much, the
will bind. These problems result in drive operation that is erratic or
Many CI700 users overcome these problems by careful
balance, and using only light tightening of the MainTitle-clutches.
will be some slippage if you bump the scope or use the faster slew
speeds, but you can still track and guide well. Indeed, the original
owner of my mount did just that, and claimed to produce over 300
successful images! Other CI700 users, like myself, can't avoid
tinkering and have modified the CI700 for better operation.
one is easy. My solution for the motor-clutches is to simply insert
some thin paper gasket material between the steel gear and the spacer
that are on each of the worm shafts (see pic). This greatly increases
the friction between the gear and the spacer when the clutch is
engaged. The result is that only light tightening is required to lock
the motors to the drives. You can get a sheet of thin paper gasket
material at any auto-parts store.
fix should only be attempted by someone who is handy with tools and
brave enough to disassemble their investment (gulp!). It involves
replacing the plastic thrust-bushing with a roller thrust-bearing. The
result is that the CI700 clutches can be tightened as much as you
and the drives still operate with no binding.
part is removing the "disk-nut" at the bottom of each shaft. This
disk-nut is round, 2" wide, 1/4" thick, and threaded onto the shaft to
hold everything in place. It is designed to be removed with a special
spanner tool - The pegs of the spanner tool fit into the small holes at
the bottom of the disk-nut and allow it to be turned. Good luck finding
I ended up using a hammer and punch to bang on
the holes of the disk-nut in a CCW direction to remove it. This caused
some marring on the disk-nut, of course. To allow easier
tightening/loosening in the future, I drilled out one of the holes and
tapped in a small machine screw. Now I can tighten/loosen the disk-nut
by tapping on the screw in a CW/CCW direction, making it easier and
The thrust-bearing I use is the same used by other CI700 users:
links). The neat thing about this thrust-bearing is that the outside
diameter is the same as the inside diameter of the existing plastic
bushing - It just drops in place!
thrust-bearing is slightly thicker than the plastic bushing, so the
brass gear sits up a bit higher in relation to the worm. Surprisingly,
this did not seem to cause any tracking or drive problems, but it still
bothered me that the worm and gear were not aligned. I fixed this by
adding shims to raise the height of the worm-housing (see pic). Others
have resorted to milling out a recess in the plate that the
thrust-bearing sets into (to lower the brass gear), but I feel this is
a bit extreme.
Remember - You may be able to avoid of all this
tomfoolery by carefully balancing the mount in both axis, only using
light tightening of the CI700 clutches, and accepting the fact that
there will be some slippage when you slew fast or handle the scope.
Mods to Make Life Easier
locking swing-handle in the center-left allows Azimuth adjustment
without tools, and can be swung out of the way without changing the
adjustment by lifting and turning. Reid #RK-165.
The big knob in
front allows Altitude adjustment without tools. It's connected with a
3/8" female coupling pressed over the allen-bolt head, and secured with
a set-screw. Reid #RK-35.
DSCs now connect with 6-pin phone-style connectors instead of the
pin-style connectors which are prone to breakage. The phone-style
connectors can be found at most hardware stores, and the covers are
made from a small Radio Shack project box. An indispensable tool for
making cables for this kind of mod is a Modular Plug Crimping Tool.