OSS Assembly

 

Revised 12/10/99

M. Radovan

Lick Obs.

Step 1: Install fixed Prism

1a- Install the OSS handling fixtures. Use the swivel eye locations mark "oss only" to handle the OSS. For all operations except camera installation the OSS can be lifted and rolled by two people. Although the OSS’s center of gravity will change as optics are installed the out of balance moment will remain very manageable.

1b- Roll the OSS using handling fixture to bring the moving prism base plate level and face up. Unbolt and move the base plate as far out of the way of the fixed prism hole as possible by sliding the base plate on the oss. Hold the moving prism plate in place with a c- clamp.

1c- Roll the OSS to level the fixed prism plate. Lower the OSS on to jack stands to stabilize.

1d- Install pipe insulation pad on the cross bar to prevent damage during prism installation.

1e- Remove imaging mirror kinematic closet to the fixed prism when in position.

1e- Install the fixed prism from the filter wheel side. Lexan protective covers should be in place before handling. Two people are needed to handle the prism. The top of the prism should be tilted in under the cross bar and then the prism is rolled in until it is sitting flat on the mounting surface. The prism should then be slide into the OSS until the 4 tapered dowel pins can be installed to line up the prism (These pins remain in the base after bolting). BE CAREFUL NOT TO PUSH THE PRISM IN TO FAR! IT CAN COLLIDE WITH THE KINEMATIC FOR THE LD MIRROR!

1f- Bolt the Fixed prism to the OSS with 16 – M6 cap screws. Snug to 10 N-M.

1g- Re-install kinematic for imaging mirror

 

Step 2: Install Moving Prism

2a- Roll OSS to position the moving prism base plate level and facing up.

2b- Remove C-clamp and slide base plate back to its mounting position.

2c- Install cap screws to secure plate to OSS. DO NOT ATTEMPT TO INSTALL MOUNTING SCREWS IN THE TWO LOCATIONS HIDDEN BY THE LIMIT SWITCHES. LIMIT SCWITCHES SHOULD NOT BE MOVED.

2d- Position moving prism stage in the middle of the OSS. To move the Prism base along the slides first remove the cap screws on the brake bracket. Pull the brake off of the shaft end and push the base by hand. This will back drive the lead screw and gearbox.

2e- Reattach brake after the stage has been positioned.

2f- Lift prism onto the stage base. (This task requires a minimum of two people but three people are much preferred). The Lexan protective covers should be on before this step. Be aware of the bottom edge of one prism face that is not fully covered by the lexan.

2g- Slide prism on plate until the mounting holes line up. Install 4 guide pins.

2f- after installing the guide pins secure the prism to the stage plate with 16 M6 Cap screws.

2g- After the screws have been torque the Transfer Base MUST BE REMOVED. IT IS MARKED WITH A LARGE RED LABEL. THIS BRACE MUST BE REINSTALLED PRIOR TO REMOVING THE PRISM FROM THE STAGE PLATE.

 

Step 3: Install imaging Mirror

3a- Leave the OSS in the same orientation as was used to install the moving prism.

3b- Attach mirror to the three blocks that are mounted on the THK linear slides. (Use flat head M4’s)

3c- Attach the mirror Frame to the cam Follower (M6 Low heads)

 

Step 4: Install Low Dispersion Mirror

4a- Remove the Cam follower from the mirror frame ( 2- M6 Low heads)

4b- Insert mirror and frame into OSS. Attach the frame to the THK Slides with M6 Low head screws. (6 places)

4c- Reattach cam follower to frame

4d- Slide mirror back to bracket. Attach angle bracket to the lead screw with 4 long M6 screws

 

Step 5: Install Camera

5a- Roll OSS position indicated on the side of the OSS by the yellow label that reads " up for camera install" Support the OSS with jack stands in this position

5b- Attach lifting straps to lifting eyes for the combined weight of the OSS and the Camera. Swivel location is close enough to the center of gravity to allow two people to control the roll of the OSS when lifted off of the jack stands.

5c- Remove the center bolt for Node # 21 of the camera and replace it with the threaded rod and standoff provided to work with the lift eye for the camera. Attach a second lifting eye to the camera flange 180 degrees opposite to Node #21 on the camera flange

5d- Lift the camera with a short sling so that the "big end" of the camera is pointing down. The camera covers on both ends should be checked to insure they are secure before moving the camera.

5e - Bring the camera into the approximate position that it resides when attached to the OSS. There should be about a ¼ to 3/8-inch clearance between the barrel and the moving prism.

5f- Attach any one strut to the camera barrel by hand tightening the 22 mm hex nut which holds the ball into the socket. Attach the opposite end of the first strut to the OSS. DO NOT loosen the brass hex lock nut or else the strut length will change and the alignment will change. Attach each strut in the same manner until all the struts are connected. Once all the struts ate attached the loose balls will have adjusted to the correct angle for each strut. At this point the 22-mm nut can be tightened with a wrench until they are snug.