10 hrs of rough grinding of 24 in mirror
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
10 hrs of rough grinding of 24 in mirror
Dear ATMs,
Today we carry out another 4 hours of rough grinding on the 24 inch mirror. Upon finishing the schedule today we got a sagitta of 5.9 mm which means that we has reached a f/6.3 curve. About 50 cubic inch of glass has been successfully removed in this three days. We are half way from the ultimate f/3.5 goal.
But there is a minor problem – the little astronomical equipment store room has been turned into a mess by us. No wonder mirror grinding is a messy business.
Best regards
Chan Yuk Lun
8-2-2004
Today we carry out another 4 hours of rough grinding on the 24 inch mirror. Upon finishing the schedule today we got a sagitta of 5.9 mm which means that we has reached a f/6.3 curve. About 50 cubic inch of glass has been successfully removed in this three days. We are half way from the ultimate f/3.5 goal.
But there is a minor problem – the little astronomical equipment store room has been turned into a mess by us. No wonder mirror grinding is a messy business.
Best regards
Chan Yuk Lun
8-2-2004
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- After 10 hrs of rough grinding, the store room had been turned into a mess. The teachers will not be happy in seeing this.
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
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- 主序星
- 文章: 183
- 註冊時間: 週四 25 12月, 2003 19:38
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
Dear Mr. BandofBrother,bandofbrother 寫:點解個張磨鏡台好似唔係好堅固,我屋企都有張類似既台,不過好搖下ge bor,你點樣防止張台搖??
You are correct. The table is very shaky while we were grinding the mirror ontop. We use this table because we have no other choice, it is being the cheapest available on market.
There is a lot of misundrestanding about mirror grinding. One of them is that we must have a very robust table for doing the job. The ideal mirror grinding table should consists of a concrete cylindrical base with weight of 50 kg embedding a 6 inch ( at least ) diameter steel pipe up to waist level. Ontop of the pipe there should be a welded steel framework with a 1 inch plywood ( of course it must be circular in shape, with unkonown practical reason, but very good psychological effect ) with diameter 30% more than that of the mirror under work.
While such table is perfect for the work under consideration, a cheap folding dinning table can also fulfill the requirement. Although it oscillate and shaking quite an extend during the grinding, nevertheless it provides a very good support for the 24 inch tool and mirror. That's all we required.
Another advantage of the foldingtable is that it can serve as a dinning table, a table for reading, a table for a cup of tea........etc after we finish the mirror.
So, a folding table might be one of the greatest invention during the last century.
Best regards
Chan Yuk Lun
9-2-2004
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
Dear BandofBrother,bandofbrother 寫:點解個張磨鏡台好似唔係好堅固,我屋企都有張類似既台,不過好搖下ge bor,你點樣防止張台搖??
Sorry, it seems that I have not answered your question. How can we stop the poor folding table from shaking during work ? As a matter of fact, we don't and we can't. We just let it shake and vibrate as much as it wish.
It won't hurt anyway.
Bestg regards
Chan Yuk Lun
9-2-2004
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
-
- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
Dear Mr. Wah!,Wah! 寫:嘩!買砂都用唔少錢呀!!!
26 lbs of #40 carbo costs HK$520. Fortunately we don't need that much in fine grinding. Hence we guess that we may pay a total of $1000 for purchasing the carbo and polishing agent.
The total budget alloted to build the telescope is $4500. Hopefully we don't make it over-budget.
Best regards
Chan Yuk Lun
10-2-2004
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