Orion XTG instruction manual Shaft Spring

Shaft

Spring

Figure 13. Place the three springs on the exposed threaded shafts of the mirror cell.

Figure 14. 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.

Collimation knob

Nylon washer

Figure 15. Thread the collimation knobs, with nylon washers attached, through the rear end ring and onto the threaded shafts. Make sure the knobs have at least three full turns of engagement on the shafts.

ing the six Phillips-head screws that connect the end ring to the tube (Figure 12), and then pulling the end ring off the tube.

Figure 16. Locate the area of tube that is bulging out and preventing the end ring from fully seating.

Warning: Once the rear end ring is removed from the tube, the raw edge of the tube itself will be exposed. Be careful not to cut or otherwise hurt yourself on the tubeís edge. Also, be careful not to pinch your fingers when re- attaching the assembled mirror cell onto the tube.

2.Next, assemble the rear end ring to the mirror cell. Find a clean, flat surface, and turn the mirror cell over so that the mirror is facing downwards. Place the three springs onto the three exposed threaded shafts (Figure 13). Lower the end ring onto the mirror cell so the threaded shafts pass through it, and the end ring rests on the springs (Figure 14). Add a nylon washer to each collimation knob and thread the collimation knobs through the end ring and onto the threaded shafts (Figure 15). Make sure the knobs have at least three full turns of engagement on the shafts. The mirror cell is now ready to be installed onto the lower tube section.

3.Assembling the end ring back onto the tube can be a bit tricky. This is because the large diameter and thin alumi- num 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 con- nected) to the tube, stand the tube up vertically so the raw edge of the tube is facing upwards. Line up the threaded holes in the edge of the mirror cell end ring with the holes in the end of the tube. Then, lower the entire mirror cell assembly onto the tube. There may be a bulge in the perimeter of the tube which prevents the mirror cell from fully seating onto the tube (Figure 16). Press against this bulge, and the entire mirror cell should seat onto the tube. Now, replace the six Phillips-head screws that connect the rear end ring to the tube.

7