[Corey, Greg]

SW Location (s/n 77)

A job we hope would be a one hour task turned into a day long endeavor (which is still ongoing).  Yesterday afternoon Greg drilled and tapped holes on the Pier (after the iLIGO Actuation Stack was removed).  This morning we hoisted the new HEPI Assy onto the Pier and discovered that the Support Bracket holding it was an unmodified one, and we had interference issues(!). 

So we lugged the HEPI Assy down to the ground and for safety/alignment reasons, re-installed the iLIGO Actuation Stack. 

We then went to the NE HEPI, confirmed all the HEPI Foot clamping bolts were securely holding the Foot, and also checked that all the Base clamps were torqued down to the Pier.  The Support Bracket here was then removed (note, this one only has the vertical slot modifications, not the cut out on the top of the Baseplate).

The SW Support Bracket was removed and handed over to Bubba for mods, and the NE one was installed at the SW corner.  Vertical Dial Indicators were installed at these two corners to monitor changes.

Once again, we hoisted the HEPI Assy up onto the Pier and we cleared the interference on top, but just as we were getting ready to drop bolts into the Foot on top, we discovered ANOTHER INTERFERENCE!  This time the base of the HEPI Assy ran into the top of the Bottom Plate of the Support Bracket (see photo).  {Crap!}

Greg then checked the position of the Foot just to confirm we didn't make a mistake with pre-positioning of the Foot (we were a little off and in a way which helped us, but still off).  So we now need to wait until we get a fully modified Support Bracket before we can continue anything at BSC7.

Bottom Clamps & Bent Bolts

At one point it was noticed that non-called out bolts were used for Bottom Clamps (see photo #3) for the NW & SE HEPIs.  As these Clamps were loosened up and the bolts were swapped it was noticed that it was hard to remove some of the bolts.  In fact, there was one bolt which was noticeably bent!  (see photo #2)

Looks like the bend in the bolt occurs at the interface between the bottom of the Bottom Clamp & the top of the Pier.  Apparently the 1/2"-20 set screws and the 35ft-lbs we'd been taking them too is just too much for the 1/2"-13 bolts here.  Unless someone else chimes in we will do the following in the future: 

-Torque 1/2"-13 bolt to 67ft-lbs

-Torque top 1/2"-20 set screws to 25ft-lbs

-Tighten the side 1/2"-20 set screws enough so they won't loosen up on their own.

For what its worth the stainless 1/2"-13 bolts were swapped out with the black HoloKrome bolts.  (Need to do this bolt swap on the SE HEPI, too).