ATM adventure in South Africa

Mirror Experiment gone wrong

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Mirror Experiment gone wrong
Just to show you that everything we do does not always work. We can make failures of note. I attach a beautiful but sad experiment that failed spectacularly. As you know, we cannot easily source suitable glass for telescope optics. So we make plans. The latest was getting a kiln and melting our own. We had quite good results with plate glass. The first good one (12 or 13 inch) is now in the figuring stage. Ground and polished very well. And it should make a fine mirror. While we made the glass we also built a grinding and polishing machine to do the donkey work. Unlike any other machine that is known to man, but it works better than most. Can handle optics up to 25 inches. In fact we are busy with a monster 24 inch specifically design for imaging. So the glass making and building telescopes are going well. We are first making a 16 inch proof of concept before the real monster. But... We did not stop there. We want to make fancy glass too. We found some pyrex and made a test blank. It came out OK, but the edges were not nice and had some bubbles inside. So we think that because Pyrex melt at a higher temperature we did not melt the load properly. No problem---add more heat. So we wrapped some stainless steel around it, put it back in the kiln, fired it up to 1300 degrees Celsius to melt it properly. Set the controller to ramp the heat up and soak it down through steps to anneal it properly. Three days later when we opened it we found this. The steel melted at about 1200 degrees, and fused into the glass, which flowed out of the now melted former, and over the edge of the shelve on to the kiln bricks below where it soaked into the porous bricks, making a really colourful mess. we had to break out the kiln bricks to get all the mess out. Me and my friends spent the whole afternoon re-laying new bricks into the kiln. Now we have a "new" kiln again-- ready for the next experiment.
Posted by Doug on July 2, 2013 Full Size|

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