R. Crouch, B. Weaver, I. Abouelfettouh, J. Oberling, R. Thompson

Today we placed and aligned the BBS SUS cage on the WBSC2 ISI.  In the morning we rough placed the SUS, and thought we had done a really good job on the first attempt.  However, that was fed by a misread of how the Build/Inspect function in PolyWorks, well, works, and upon doing a more thorough measurement (directly measuring a constraining plane to inform SMR radius compensation instead of letting PolyWorks handle it automatically) we found there was a position and rotation error to the cage.

In the afternoon we moved the SUS cage around until things looked really good.  We were well within our +/-1.0 mm XYZ tolerance, but once the SUS had been fully dog clamped to the ISI things shifted (as they do).  In this case, it was roughly 0.5 mm in the +Y direction.  All of our measurement points except one are within tolerance, so we called this good enough for SUS cage placement.  To end, Ryan and I measured the circle that's defined by the lower section of the Figure 8 (the round section of the SUS cage that surrounds the BBS) on both the HR and AR sides of the cage.  The first attachement shows the position deviations of the 4 points we used for cage placement/alignment and the current position of the HR and AR Figure 8; all except the Y axis position of 1 point are within our tolerance.  The second attachment shows the rotation of the SUS cage w.r.t. the ISI; the angles listed are in degrees and are measured from the positive axes they are associated with (so X Ang is measured from the +X axis).  These 2 lines show that the SUS cage is rotated roughly 400 - 500 µrad CCW (top-down view) from nominal.

Next up is to set up a total station looking at the AR face of the BBS to precisely align the optic to the ISI.