PROCEDURE:

1. Remove secondary, put in box. Use two block and tackles (one from support, one we bought in 1999) to hold the mirror up while it is being unscrewed, as the assembly weighs around 50 pounds. The three innermost bolts, with hex heads are the ones to unscrew. The earthquake stops must be removed. The mirror is detached from the assembly via the three allen head screws, once these are out, the mirror may be wedged away from the assembly (the tripod that is RTV'd to the glass stays with the glass). Keep track of the belvel washers.
2. Remove stovepipe and corrector
3. Remove counterweight on top ring, replace with restraining rod clamp.
4. Install restraining rods (kept on upper level). First do Dec rod, the shorter rod, with telescope at horizontal position, tweak Dec motion until ball at end of rod seats in the clamp. The other end is bolted to a square shaped bracket on the polar axle near the north pier. Use a large open end wrench and a large screw driver which holds the nut in place to tighten bolt. Bring scope to zenith and install RA rod, one end goes on main counterweight arm, the other on the eyeloop on the north pier, about 4 feet off the floor. This rod should be expanded as much as possible, because when the telescope is unbalanced in RA, the tendency will be to compress the rod.
5. Loosen worms on both axes, watch for telescope motion.
6. Remove earthquake stops
7. Remove all mirror covers so that the struts will clear the covers when the cell is lowered. Mark the covers, as they are unique (make sure the numbers on the doors are legible). It may be possible to leave the actuators in place.
8. Remove instruments and back plates of cell
9. Detach finder, tie to telescope at the top, remove electronic boxes.
10. Remove radial counterweights, by loosening the nuts at the bottom. Rods may also be removed now by removing bolt that holds them in the actuator joints.
11. Hook up chain hoists and cart. A shackle is needed on the eastern corner of the cart, to make the chain reach the cart.
12. Raise cart to the cell, make tight.
13. Unbolt cell, tape shims to struts so we don't lose them
14. lower cart to about 3 feet off the floor.
15. Remove radial hard points.
16. Remove radial actuators. There is a special wrench for this task, called a crows-foot. Remove the screw that pins the rotation restraints. This is done from above the mirror, using a ball driver.
17. Undo Lou's spring restraints underneath the cell.
18. Use 3 sets of two 44" straps tied together to remove the mirror. Each set should be snaked under the mirror (clocked at 120 degree intervals). Strings were left under the mirror to help start this procedure. The mirror may be raised on its jacking points to help position the straps. The straps should all be attached at the center to the chain hoist.
19. Place one long yellow strap around SE upper truss, and another at NW truss, connect with looped pink straps, and attach one of the hoists at the juncture, which is now in the center of the telescope.
20. Lift mirror from cell.
21. Remove cart and cell.
22. Move box underneath the mirror. Leave the straps in the box.
23. Seal box and ship with secondary.

REATTACHMENT:

Raise jack points so that mirror will sit on them instead of hard points.

Watch radial hard points as they might be clipped off when reinstalling the mirror.

Use straps as above to lower mirror into cell. Make sure straps are at 120 degree intervals before raising mirror up.

Mirror must be realigned in same orientation, such that the rotational restraints can be hooked up. Engage axial actuators while mirror is on jacking points. When this is done, lower jacking points and engage the rotational constraints.

Set centering after mirror is fully in and axial actuators are engaged. Use gap gauge to do this with respect to center hub. Wooden wedges may be used at edge of mirror, on the pucks.

Occasionally have to bend struts to get them to mate to the cell bolt holes.

Replacing radial actuators is a pain. Must remove at least one bolt on the bracket attached to the cell to help screw in the ball-joint pins. It also helps to remove the weights from the rods before attaching the rods.

The spring retention system is tricky. The spring/bolt assembly must be totally taken apart to reinstall. First, screw bolt into puck which is attached to mirror, the short thread side goes in - a nut is threaded here to stop the bolt. Then place the bracket next to the cell (note that one bracket is bigger than the others since the holes are different sized). A large washer comes next, followed by the spring, followed by a small washer, followed by the nut. The idea is for each spring unit to have 40 pounds of force. The purpose of that is to pull the primary back down on the hard points, the mirror having been floated by the axial counterweights. The hard points themselves are spring loaded, so too much force is also a bad idea.

See the memo by Lou Boyd for explicit instructions.