September 9, 2016 – Now that the M1M3 mirror cell has been welded and stress relieved, the initial machining of the M1M3 cell weldment has begun at CAID Industries in Tucson. This short video shows the machining of the +4000 interface holes and precision interfaces between the cell and the glass mirror and the cell and the coating chamber. The flange ring getting machined in the video is the circular “ridge” shown in the first image.
The M1M3 cell mounted to the support stand “spider” on the rotary table of the Toshiba horizontal boring mill (HBM) in the background at the CAID machine shop in preparation for phase 1 machining. Phase 1 includes machining critical surfaces on the top face of the cell such as the large circular vacuum flange ring. The flange ring, which is slightly larger than the 8.4 m diameter M1M3 mirror, is the interface that the coating chamber will attach to during mirror aluminizing operations. The cutouts in the deck plate on top are for the mirror support actuators that will mount inside the cell and protrude through the cutouts to support the mirror.
Close up of the vacuum flange ring being machined. The entire cell is rotated on the rotary table and the cutting tool is stationary. Note that the vacuum flange inner diameter was slightly higher than the outer diameter as seen by the material being removed. Upon completion of this machining operation, the overall flatness of the vacuum flange was measured to be 0.18 mm [.007”], which is within the 0.30 mm [.012”] requirement.
View of the top surface of the M1M3 cell with the vacuum flange being machined on the Toshiba HBM. The cutouts in the deck plate are masked off to prevent chips from falling into the interior of the mirror cell.
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