Tuesday, May 19, 2009

Amazing Work Progress

The maniacs in casting at the Mirror Lab are making tremendous progress on the new mold for the 6.5 meter Mexican project. I just posted on their start on Friday and in the 2 work days since then, they have installed over 70 cores per day and are already over 15% finished! As a reminder, the left image shows the 20-some cores they installed on Thursday (they work 4-10 hour days, so didn't work Friday). Today's image is shown on the right. In talking to the crew, they are averaging about 10 cores per hour. At that rate, they should be done in a couple weeks - unheard of!

As I mentioned on the Friday post, they need the hollow cores left open to ream out the crosspin holes, and glue in the pins as the new cores are set into place. In the closeup at left, you can see the open holes facing the camera where the crosspins will be installed, and in the gaps between the cores, you can see the pins that join one core to it's neighbors and increase the mold's overall rigidity. Once a core is pinned to all it's neighbors, they can glue in the core top. The 3 dabs of blue coloring per top is where they drill and insert ceramic pins to mechanically join the core body to it's top. It is very similar to cabinet work where dowel pins are drilled and glued into place to strengthen joints and bond lines. The blue goo (affectionately called "Smurf Glue") is equivalent to spackling's filling of nail holes, and is used to fill in the gap where the pin is located. Damon is going over each core top and filling in each of the gaps.

Meanwhile, over on "my" side of the Lab, where we grind and polish the mirrors, there is no lack of activity. A snapshot of the Polishing Lab shows the Giant Magellan Telescope (GMT) pulled under the test tower for a lasertracker measurement. Since we are still in fine grinding (9 micron loose abrasive), the mirror is not yet polished (though at near-grazing angles, you can start to see the lab lights reflected in the surface) so a lasertracker (distance-measuring theodolite) measuring the surface height of a corner cube has been utilized to map out the surface and guide the figuring operation (improving the surface quality). In the background, the Large Synoptic Survey Telescope (LSST) can be seen on the Large Optical Generator machine in the background. Work has been proceeding on the backplate, and loose-abrasive grinding is about to start. Big glass??? Lots of it around here!

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