Thursday, April 30, 2009

Invar buttons everywhere

The clean room dress code's strictly enforced, even for local wildlife...

With various workshop jobs in progress, the redundant astronomers set off to explore two of the newer telescopes on site: SLODAR & MoNet South.

The latter was painfully close to getting going earlier in the week when the roof mechanism suffered the same catastrophic failure MoNet North experienced a couple of years ago :(

Meanwhile, back at SALT, the main task for the day was to attach custom made Invar buttons to all the SAC mirrors. These cleverly shaped, thermally invariant bits of SAC bling will enable us to make repeatable measurements of the mirror positions using the Faro Arm.

The backs of M2 & M4 are both painted black so small patches of the paint had to be stripped off before the buttons could be glued on.

While I was quietly enjoying a manicure from Francois, Darragh proclaimed himself cameraman & snapped a few pics. He's subsequently pulled rank & insisted that at least one of his shots make it into the blog, so here it is!

Actually, Francois was dabbing tiny blobs of epoxy onto the backs of the buttons. They were stuck face-down on strips of duct tape that would later be used to hold them in place while the epoxy cured.

For those hard to reach places, an advanced applicator system (consisting of a lump of Prestik on an allen key) was successfully employed...

The backs of M2, M3 & M4 each got 6 buttons while M5's 6 had to go around the outside edge of the mirror. The pic below shows the first button in place on M4 & no, the vertical streak wasn't an accident - that's how the mirror was painted (it can also been seen in one of the shots in the 19 April post).

The M3 set would've done a chiropractor proud for the level of back-mangling involved - well done James!

Eben stopped by during the course of the evening & showed us his latest work of art - an absolutely incredible piece of craftsmanship!

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