天文望遠鏡製作 2007 (第七課-實習課3) 10 June 2007

layanata · 文章由 **layanata** » 週日 10 6月, 2007 12:26

今天我沒有時間來啊! 豆貓有影相嗎?

Wah!! · 文章由 **Wah!!** » 週日 10 6月, 2007 14:20

今日我同豆貓都有事幹, 同樣來唔到呢...

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 21:33

Wong Sir asked me to post toady's practice lesson pictures beacuse layanata is not with us today.

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 21:48

The best polished rim (2 mm thick) in preparation for the next practice session. Thanks to one of the students from today.

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 21:52

Thanks to Wong Sir's teaching.

Look! The professional Amateur Telescope Maker at work!

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 21:55

Wong Sir asked me not to forget to post the comparison pictures of grain size 120 and 220 for the class students to compare.

The grain size of 120 from 27 May 2007 practice lesson.

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 22:32

The grain size of 220 from today practice lesson 10 June 2007.

I had spent 2.5 hours on 27 May 2007 prcatice lesson trying to get the grain size evenly using sand #120. I was unable to achieve the desired result because I tried to do the same number of strokes instead of polishing at fixed duration.

Today, Wong Sir insisted me to follow his 3 minutes run instead of fixed number of strokes. I was able to achieve some improvement following Wong Sir's advice where the grains were approaching evenly from rim to center after polishing for 1 hour today (total hours spent was 3.5 hours). Some large grains left from sand #80 were still left behind going into polishing with sand #220.

Again, following Wong Sir's exact adivce of doing each run for 4 minutes, the grains on my main mirror glass were very evenly distributed from rim to center. All the grains from sand #80 and #120 all disappeared. I did 13 runs of 4 minutes each with 3 of the runs having the tool on top of the main mirror. The results were amazing and I am ready to go into sand #320 next week! Thanks, Wong Sir.

豆豸苗 · 文章由 **豆豸苗** » 週日 10 6月, 2007 22:38

呢張相好得意:

Wah!! · 文章由 **Wah!!** » 週日 10 6月, 2007 22:42

tommy_tse 寫:The grain size of 120 from 27 May 2007 practice lesson.

條邊崩崩地, 係唔係磨得太大力, 或者銼邊唔夠呀?
有無試用電筒釗曲率半徑?????

tommy_tse · 文章由 **tommy_tse** » 週日 10 6月, 2007 23:17

I think it may be from rim polishing.
I have not done another test using 電筒釗曲率半徑 since the last time you showed me at Practice lesson I on 20 May 2007.

豆豸苗 · 文章由 **豆豸苗** » 週一 11 6月, 2007 10:11

呢條邊真係銼得好靚喎, 冇崩又夠深~
相信幼磨落去都唔使再銼邊了!!

Wah!! · 文章由 **Wah!!** » 週一 11 6月, 2007 13:37

tommy_tse 寫:I think it may be from rim polishing.
I have not done another test using 電筒釗曲率半徑 since the last time you showed me at Practice lesson I on 20 May 2007.

度深度是間接量度焦距的方法, 電筒測曲率半徑或陽光測焦距係一個直接量度的方法, 準確度遠比前者高.
係粗磨及幼磨初期"必須"的步驟.
未做過呢個測試的同學一定要係家中試試喇!

Nosneb · 文章由 **Nosneb** » 週一 11 6月, 2007 14:26

Wah!! 寫:度深度是間接量度焦距的方法, 電筒測曲率半徑或陽光測焦距係一個直接量度的方法, 準確度遠比前者高.
係粗磨及幼磨初期"必須"的步驟.
未做過呢個測試的同學一定要係家中試試喇!

其實今年好開心, 頭兩堂實習都好好陽光. 可以玩陽光試焦距. 我上年就堂堂都天陰陰, 冇得玩, 冇計!

Hay · 文章由 **Hay** » 週三 13 6月, 2007 23:00

睇o黎今年同學們D進度真係好快，佢地應該有更多時間去拋光同拋物線化塊鏡。希望今年個個同學都可以磨到效果滿意o既鏡！

Hay

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