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Log, Apr 13, 2007

28 people. I want to thank everyone who helped with the repair of the dome shutter. It turned out to be a MUCH larger job than I had expected, and a lot more complex. As Joe Hartley and Ernie Evans can attest, the dome motor, gear box and transmission is not exactly light. In fact, it is really heavy, bulky, and balky. It was in an all but impossible to reach safely. It couldn't have been done at all except for the scaffolding that Bob Whyte brought over to the dome. Nor could it have been done by a single person either going down or going up. And yes, the motor really was broken, not just "unplugged" or the equivalent. There was a wire inside the motor which had worn away until a contact was gone, just enough to cause a hum, but nothing else. I'm not exactly sure how or why, but once it was fixed it ran like a champ again.

I don't think it would have been possible to repair the motor without lowering it. There simply wouldn't have been enough room to open the motor. Besides, there were five sections which might have been broken - the "limit" switch, the capacitor box (the original suspect), the step down transmission, the motor (the real culprit) and the large dome gear array. We had to do all the work, but it was a brute. Stephen Eaves, Joe and I spent more than an hour trying to replace the capacitor unsuccessfully. Oh, we replaced it, but since it wasn't the problem, it didn't fix anything. Then Bob Whyte and I spent a bit more than an hour setting up the scaffolding. I then spent another hour and a half deciding how to take the whole unit down, loosening bolts and making sure than nothing was rusted in place. Ernie Evans and I spent three hours or so actually getting the beast down. NO EASY TASK! The next day I brought it to Piela Electric in Preston Connecticut. It took several days before they saying it was fixed. Finally!

We had gravity to help bring the motor, gears, transmissions down, but if I didn't buy a block and tackle, it would still be sitting on the floor of the dome. Well up it went. Then Joe and I lashed it safely with cargo straps. The unit is basically a triangle and we got the three corners of the triangle bolted fairly snugly, but we still had the really tricky part of put the gears back in place (within a small fraction of an inch). The problem was that merely snugging the bolts was not enough to lift the unit in place. There were two "clamps" which reached behind the 9 foot gear attached to the dome and snugged it against the drive gear. These clamps had to be bolted more by feel than by sight. Worse yet they had to take the entire weight until everything was in place. NOT POSSIBLE! So Joe and I dragged a step ladder up onto the platform. We placed a car jack on the top of the step ladder and cranked it up until "clink!" the gears snapped in place. Suddenly the two "clamps" could place. Some more tightening and everything was back in place.

Joe hooked up all the plugs and switches and with a few crossed fingers we turned the beast on. Up came the dome! Yeah. We ran it down after we got it up a foot, and down it went just fine. We needed to check out the limit switches, so we ran it to the top and it shut off just as it should. Going down all the way worked perfectly too. Many high fives and right ons! We were done, or at least almost done. We reattached the cables, took down the scaffolding and went home.

Altogether, the work came to perhaps 15 hours - most of it really heavy labor. I have to admit I am tired but I am so pleased. Many thanks everyone! And oh by the way, if it ever breaks again - I think I'll find somewhere else to spend my winter holiday.

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While we were observing at Frosty Drew tonight, on the far side of the world, we had an occultation that I wish we could have viewed. The Moon occulted Mars during the evening hours here but with the Moon setting in the afternoon, we missed it. In Asia they are luckier. They will see it just after Moon rise - around 4 AM at their local time.

Can you say "Cub Scouts" boy and girls? And Moms and Dads and brothers and sisters? What better way to bring the Observatory out of its dormancy than to have a crowd of exuberant kids having what I'm sure was a great time? We didn't get to view a whole lot of objects because every kid really wanted to see Venus or the "baby" stars in the Trapezium, or to play with the AstroScan himself (or herself) or too learn where the constellations begin and end, and why some stars are red and others are blue.

I can say with a combination of happiness and relief that the shutter opened and closed perfectly smoothly. I certainly wouldn't want it ajar with the predicted gully washer of a nor'easter on the way.

-Les Coleman

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Apr 13, 2007
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Leslie Coleman's Log
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