Background

Removal of the ESI collimator actuators is a delicate operation which should only be performed by trained instrument technicians. This procedure documents the steps followed when removing the actuators in June 2007, completed by Mike Wagner and Dwight Chan of CARA and Jeff Lewis and Matt Thompson of UCO/Lick.

Requirements

Time: approx 4 hours
Telescope Considerations
- ESI on Keck II Nasmyth deck
- No telescope restrictions
Tools
- 10mm socket wrench
- Allen wrench set (metric)
- 3/4 in wrench
- 10 mm wrench
Materials & supplies
- ESI rotator controller ("Arnie Box" )
Personnel
- Three instrument technicians
Relevant ESI Drawings
- TBD
Prerequisites
- ESI collimator mirror removed per procedure.

Procedure

Remove the collimator support struts and nodes. NOTE: exercise great caution because these vanes are extremely fragile! Proceed as follows:
- Drive all collimator actuators to raw position 200,000 encoder counts using the following commands:
```
	modify -s esi coll1raw=200000
	modify -s esi coll2raw=200000
	modify -s esi coll3raw=200000
```
- Use 4mm Allen wrench to remove the 4 screws on each node which attaches the strut to the actuator. Note: support the struts by hand to prevent them from flexing.
- While allowing a minimum of flexure to the assembly, detach 2 nodes from the mask by using the 5mm Allen wrench to undo the 2 hex bolts, allowing you to remove one node from the housing.
- Re-attach one of the detached nodes to the mask.
- Repeat the previous 2 steps to detach the other two cars from the actuators.
- Re-attach all nodes to the mask. Using great caution, transport the entire node/strut assembly to a secure location and set it down in a fully supported position to prevent flexure of the struts.
Disconnect actuator from electronics:
- Turn off power to the actuators by using the motor control software to put the stage in HALT mode. Issue the following command on the ESI host computer:
```
	modify -s esi coll1mod=halt
	modify -s esi coll2mod=halt
	modify -s esi coll3mod=halt
```
- Remove side panels as needed to access electronics controllers.
- Remove the actuator controller box cover and disconnect the ribbon cable, plus DB15 and 2 CPCs.
Remove actuator from housing:
- Remove the round covers on the actuator housings by using the 3mm Allen wrench to remove the 12 socket head cap screws on each cover.
- Use the 10 mm wrench to remove the 6 6mm hex head bolts which define the actuator in place. Note that each bolt has 2 spherical washers which must remain oriented correctly. IMPORTANT: do not disturb the yellow shrink-wrapped set screws within which the bolts are set!
- Use 3/4 in wrench to loosen the 2 locknuts which are on the non-shrinkwrapped set screws.
- Use 10 mm wrench to loosen the 2 defining set screws to which these lockbuts are attached, until they do not protrude into the housing.
- To remove unit, pull actuator assembly out of the housing and feed cables through the back of the housing.
- Use 10 mm wrench to re-tighten the set screws so they remain in place.