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clear Fig 23

Figure 23 - OTA side mount
plate with 4-40 screws


Rotate the scope to the 12 o'clock position and lock the RA. The reflected beam should now be on the first mark. If the second mark is to the right of the first mark then the 3 o'clock side of the OTA must be slid forward or the 9 o'clock side must be slide back. If it is to the left then the opposite applies.

Before making any adjustments it is wise to gauge where the OTA is presently positioned in the OTA side mount plates. At the rear of each OTA side mount plate are two threaded holes. Each hole leads to the bolts in the OTA side mount plate. There are a total of four holes. One for each of the four bolts. Insert a 4-40 machine screw into each threaded hole and screw it in until it hits the bolt. Once it hits the bolt back it off until it just disappears from the bolt slot into the OTA side mount plate while counting the number of turns. Do this for all four bolts and record the number of turns. This will allow you to return the OTA to its original position should you decide to do so.

After recording the original location of the OTA you are now ready to reposition it. Loosen the three screws/bolts on the OTA side mount plate that you plan to move. Moving the OTA forward is simply a matter of screwing the 4-40 screws up against the bolts. Once against the bolts continue to turn the screws until the reflected beam is half way between the two marks. This will push the OTA forward on that side. Tighten the screw/bolts.

To move the OTA backwards make sure the 4-40 screws are fully retracted from the bolt slot. Grab the fork arm with one hand and the front of the scope with the other and push the OTA to the rear until the bolts butt up against the rear of the slot. Tighten the bolts and screw and recheck the positioning of the reflected laser beam. There is a good chance that pushing the OTA all the way to the rear was too much movement, but that is OK. Each adjustment will now involve moving the OTA forward with the 4-40 screws. Using the screws to move the OTA forward allows you to better gauge the true position of the OTA and lends itself to repeatable positioning. Screw the 4-40 screws forward until the reflected beam is half way between the marks. Tighten the screws and record the number of turns for future use.

Tape a new piece of paper on the wall and repeat this step until you have reduced the gap between the first and second marks as much as possible.

Step 6. Slowly rotate the scope 360º and note the diameter of the circle swept by the reflected beam. I was able to reduce the circular sweep of the reflected beam to less than 1" at 22' using this procedure.

Repeats steps 3, 4 & 5 until you have reduced the circular sweep as much as possible.

With the DEC setting at a near perfect 90º now is a good time to set you DEC circle before unlocking the DEC knob.

It would probably be a good idea to inspect the DEC and RA drives for proper gear meshing before using the scope. If you had to make major adjustments to the fork arms the DEC gears could possibly be misaligned due to the arm adjustment. I m not sure if the RA gears would even be affected by any part of this procedure but it is better to be safe than sorry.

The procedure is now complete.

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