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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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Dear ATMs,
I am often asked whether amateur telescope maker are doing crazy thing. My answer is – yes, we are!. Things get incredibly crazy.
What takes months to accomplish we make it in just a few days, thanks to the crazy human fresh grinding machine. Today, after a total of 39 working hours the mirror blank finally received its f/3.3 curve. Rough grinding was over.
There are altogether 200 cubic inches, or about 16 lbs, of solid glass has be removed away from the mirror blank. ( If we also count the glass removed from the tool, we totally remove over 30 lbs of glass away !!!. That sounds really crazy. ). We have passed the toughest part of 30 inch mirror making.
Below are some statistics :-
Amount of #40 grit used : 60 lbs.
Final focal length of mirror after rough grinding : 99 inches, f/3.3
Depth of concave surface at center : 14.4 mm
Thicknes of mirror blank at center : 9.9 mm
Final weight of mirror blank, after rough grinding : 40 lbs.
Total construction cost, up to now : HKD 3074
Shaping of the mirror will be commenced tomorrow. At the moment everything is running extremely smooth. We are running ahead of schedule.
Human fresh is actually very powerful machine. It transforms hamburger into working force magnificently.
Best regards
Chan Yuk Lun
1-4-2005 |
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| Close-up view of above picture, clearly shows that the sagitta is 14.4 mm. |
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| 檔案描述: |
| Close-up view of above picture, clearly shows that the sagitta is 14.4 mm. |
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| 檔案大小: |
52.64 KB |
| Viewed: |
檔案已被下載 11567 次 |
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| 檔案描述: |
| Measuring the concave depth ( sagitta ) using a simple steel rule and straight angle bar. At f/3.3 sagitta should be 14.4 mm. You can see how steep the curve on the mirror blank is |
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| 檔案描述: |
| Measuring the concave depth ( sagitta ) using a simple steel rule and straight angle bar. At f/3.3 sagitta should be 14.4 mm. You can see how steep the curve on the mirror blank is |
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| 檔案大小: |
76.85 KB |
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檔案已被下載 11567 次 |
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| 檔案描述: |
| The last round of rough grinding. |
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| 檔案大小: |
93.46 KB |
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檔案已被下載 11567 次 |
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| 檔案描述: |
| The last round of rough grinding. |
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| 檔案大小: |
93.46 KB |
| Viewed: |
檔案已被下載 11567 次 |
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豆豸苗
夸克星
註冊時間: 2003-06-28
文章: 9868
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| Chanlunlun 寫到: |
| Thicknes of mirror blank at center : 9.9 mm |
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Wah!
夸克星
註冊時間: 2003-06-28
文章: 9061
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忽發奇想!
如果主鏡中心開個洞做個卡式,一定可以做到一個高速太陽燒烤爐!  |
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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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| 豆豸苗 寫到: |
| Chanlunlun 寫到: |
| Thicknes of mirror blank at center : 9.9 mm |
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Dear Miss BeanKitty,
Yes, that's what I call carzy.
May be this is a record of the thinnest 30 inch mirror in the world.
Best regards
Chan Yuk Lun |
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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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| Wah! 寫到: |
忽發奇想!
如果主鏡中心開個洞做個卡式,一定可以做到一個高速太陽燒烤爐! |
Agree! |
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chrislichi
夸克星
註冊時間: 2004-09-30
文章: 2005
來自: SKY
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9.9m....我發夢都想不到這數字出現於Thicknes of mirror blank at center .... |
_________________
*******SYY HOPPER******* |
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Tarepanda
夸克星
註冊時間: 2004-11-08
文章: 8115
來自: 香港
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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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| Tarepanda 寫到: |
哇
搬動時不就要很小心羅? |
Dear Mr. Tarepanda,
Yes indeed. After rough grinding the weight of the mirror blank reduces by a greart deal. Now one student is abel to lift up the whole blank. It is much easier to transport the mirror now compared to a week ago when rough grinding had not been started.
Of course we need to watch out during transportation. Actually we do not wash the mirror, we do not leave the mirror out of the table at all except for measurement of curvature.
Best regards
Chan Yuk Lun |
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豆豸苗
夸克星
註冊時間: 2003-06-28
文章: 9868
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咁幼磨時可唔可以唔洗鏡?  |
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sodium
白矮星
註冊時間: 2003-06-29
文章: 756
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| Chanlunlun 寫到: |
| 豆豸苗 寫到: |
| Chanlunlun 寫到: |
| Thicknes of mirror blank at center : 9.9 mm |
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Dear Miss BeanKitty,
Yes, that's what I call carzy.
May be this is a record of the thinnest 30 inch mirror in the world.
Best regards
Chan Yuk Lun |
走火入魔XDDDD |
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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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| 豆豸苗 寫到: |
| 咁幼磨時可唔可以唔洗鏡? |
Dear Miss BeanKitty,
In fine grinding we never wash the mirror, except in changing a finer grade of carbo.
As you can imagine the process of washing the mirror, when at as such aperture, is a big and time consuming business. It's not justified to spend time and effort to just "wash the mirror clean" . We better avoid it if it could be avoided.
Best regards
Chan Yuk Lun |
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豆豸苗
夸克星
註冊時間: 2003-06-28
文章: 9868
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| Chanlunlun 寫到: |
...In fine grinding we never wash the mirror, except in changing a finer grade of carbo.
As you can imagine the process of washing the mirror, when at as such aperture, is a big and time consuming business. It's not justified to spend time and effort to just "wash the mirror clean" . We better avoid it if it could be avoided.
Best regards
Chan Yuk Lun |
明白, 但唔洗鏡如何檢查砂眼呢? 或如何知道幾時要轉砂? |
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豆豸苗
夸克星
註冊時間: 2003-06-28
文章: 9868
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嘩. sodium 突然浮番上來呢~~ |
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Chanlunlun
夸克星
註冊時間: 2003-10-09
文章: 2207
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| 豆豸苗 寫到: |
明白, 但唔洗鏡如何檢查砂眼呢? 或如何知道幾時要轉砂?  |
Dear Miss BeanKitty,
As mirror washing is a big business we never inspect "holes" on the mirror surface except when time comes we change into a finer grade of carbo. Only at this instance do we wash clean the whole mirror blank and only then do we have a chance to inspect the mirror surface.
We fine grind each grade of carbo for 2 hours, which is suficient to gurantee a fine enough surface and after two hours of fine grainding we change into a finer grade with or without inspection. We normally discover one or two "holes" on the mirror surface but it doesn't matter since they will eventually gone after 1200 or 2000 carbo.
Best regards
Chan Yuk Lun |
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