天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
不好意思啊, 這兩日去了坐井Camp, 因為太夜沒有通知黃sir我不能前來磨
鏡班, 今天豆貓有來嗎? 煩請各位報告一下今天情況和貼一些相片, 感激感
激啊!
鏡班, 今天豆貓有來嗎? 煩請各位報告一下今天情況和貼一些相片, 感激感
激啊!
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Today, I have learned quite a lot. Mostly importantly, Wong Sir said he had put money in my pocket and I have "absorbed" five years of his experience in just a few minutes. Let me tell you how in the following picture narratives.
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
I began today with sand #320. I started at 10:15 am and completed #320 at 3:15 pm with one hour and 15 minutes lunch break. In total, I had done 17 runs of 4 minutes and 30 seconds each to complete #320 polishing stage.
After 3 runs, Wong Sir taught us to use W-Stroke instead of Diametral Stroke so that we could get familiar with W-Stroke to do fine correction on mirror and tool matching as well as circular zoning problem.
My dearest tutor Choi Sir also examined my mirror after the 8th runs. The grains were unevenly distribured with better polishing in the center than the rim. I then continued with another 3 runs (a total of 11 runs completed before lunch) with the last run turning the tool on the top to polish the main mirror as instructed by Wong Sir. That works very well and the grains were evenly distributed.
After 3 runs, Wong Sir taught us to use W-Stroke instead of Diametral Stroke so that we could get familiar with W-Stroke to do fine correction on mirror and tool matching as well as circular zoning problem.
My dearest tutor Choi Sir also examined my mirror after the 8th runs. The grains were unevenly distribured with better polishing in the center than the rim. I then continued with another 3 runs (a total of 11 runs completed before lunch) with the last run turning the tool on the top to polish the main mirror as instructed by Wong Sir. That works very well and the grains were evenly distributed.
- 附加檔案
-
- First_Examination_320_#1.jpg (138.73 KiB) 已瀏覽 10965 次
-
- First_Examination_320_#2.jpg (159.86 KiB) 已瀏覽 10965 次
-
- First_Examination_320_#3.jpg (231.28 KiB) 已瀏覽 10965 次
-
- First_Examination_320_#4.jpg (210.68 KiB) 已瀏覽 10965 次
-
- Grain_320_After_W-Way_#1.jpg (162.1 KiB) 已瀏覽 10948 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:37 編輯,總共編輯了 2 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
After lunch, Wong Sir taught us to use pencil line polishing method to test degree of matching of both the mirror and tool at #320 stage. You can see my bubble test was excellent but it was not accurate enough at 320 stage. The pencil test on my mirror failed as the pencil markings on the rim remained after about 20 “dry” strokes with 10 strokes in two different direction.
- 附加檔案
-
- WongSir_Pencil_Test_#4.jpg (225.24 KiB) 已瀏覽 10959 次
-
- WongSir_Pencil_Test_#3.jpg (221.16 KiB) 已瀏覽 10959 次
-
- WongSir_Pencil_Test_#2.jpg (330.8 KiB) 已瀏覽 10959 次
-
- WongSir_Pencil_Test_#1.jpg (219.71 KiB) 已瀏覽 10959 次
-
- Bubble_Test_at_320.jpg (282 KiB) 已瀏覽 10959 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:31 編輯,總共編輯了 3 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
I did another 5 runs of W-Stroke and the pencil mark testing still could not pass. This time with the rim markings gone but the center markings were left behind after dry strokes. A few students encountered the same problem around the same time like me. Choi Sir was wondering what had happened to us and told us to do one run of Diametral Stroke – the problem vanished and it looked perfect with all pencil markings gone on the center and rim! Nice going, Choi Sir!
Here is a picture of the grain size after the final pencil mark testing.
Here is a picture of the grain size after the final pencil mark testing.
- 附加檔案
-
- Final_Pencil_Test_#3.jpg (197.14 KiB) 已瀏覽 10967 次
-
- Final_Pencil_Test_#2.jpg (199.57 KiB) 已瀏覽 10967 次
-
- Final_Pencil_Test_#1.jpg (210.62 KiB) 已瀏覽 10967 次
-
- Grain_320_Final_Before_Final_Pencil_Test.jpg (141.84 KiB) 已瀏覽 10956 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:36 編輯,總共編輯了 4 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Wong Sir said there are a few common mistakes we made when polishing #320:
(1) Too much sands so the tool and mirror were “lifted up” by the sands so polishing became uneven;
(2) We did not got rid of the bubbles between the two glasses so not all surface area were polished;
(3) We used too much or not enough water.
Wong Sir demonstrated below what an evenly distributed sands looked like without air bubbles. Don’t forget not to talk on the phone like Sky Observers’ Club past chairman Wong Sir – the two glass pieces would get sticked togther when left unattended for a while.
Our tutor Wah! Also showed us how to get grid of the air bubbles by moving the mirror too one side and then self-turning it once to get rid of the bubbles. I found this working quite well.
(1) Too much sands so the tool and mirror were “lifted up” by the sands so polishing became uneven;
(2) We did not got rid of the bubbles between the two glasses so not all surface area were polished;
(3) We used too much or not enough water.
Wong Sir demonstrated below what an evenly distributed sands looked like without air bubbles. Don’t forget not to talk on the phone like Sky Observers’ Club past chairman Wong Sir – the two glass pieces would get sticked togther when left unattended for a while.
Our tutor Wah! Also showed us how to get grid of the air bubbles by moving the mirror too one side and then self-turning it once to get rid of the bubbles. I found this working quite well.
- 附加檔案
-
- Air_Bubble_Problem_Correction.jpg (201.05 KiB) 已瀏覽 10967 次
-
- Air_Bubble_Problem.jpg (234.65 KiB) 已瀏覽 10967 次
-
- Well_Mixed_320.jpg (256 KiB) 已瀏覽 10967 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:29 編輯,總共編輯了 1 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Before I started on sand #600, Wah! and 豆豸苗 helped us to measure our mirror’s focal length by measuring the radius of curvature using light test. My mirror’s radius of curvature was 1460 mm, which is 2 times its focal length. The standard f/6 with 120 mm mirror required 720 mm focal length. I was fortunate to accidentally achieve a focal length of 730 mm!
- 附加檔案
-
- Light_Test_Radius_of_Curvature.jpg (138.66 KiB) 已瀏覽 10963 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:32 編輯,總共編輯了 3 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Wong Sir also showed us how to measure the degree of matching of the two glass pieces by reflection test under a florescent lamp to see if the refelction of the “red florescent lamp” brightness was even when moving the mirror left to right or vice versa. Don’t use pencil mark testing as it may scratch the mirror!
- 附加檔案
-
- Reflection_Test_#2.jpg (150.76 KiB) 已瀏覽 10962 次
-
- Reflection_Test_#1.jpg (215.6 KiB) 已瀏覽 10962 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:33 編輯,總共編輯了 1 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Look at this guy, he pretended to look like wong sir but I bet he did not know what he was doing! Wong Sir told this guy to go home and polish #600 and #1200 two hours each and forget about the reflection testing. Poor guy!
- 附加檔案
-
- Reflection_Test_#3.jpg (184.15 KiB) 已瀏覽 10961 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:33 編輯,總共編輯了 1 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Wong Sir also showed us how to examine the grains of #600 above by back lighting via a 10x loupe. Wong Sir said he hated this as the bright light hurt his eyes and he will only demonstrate to us once.
Here is the picture of the #600 grains after 2 runs of 4 minutes and 30 seconds each.
Here is the picture of the #600 grains after 2 runs of 4 minutes and 30 seconds each.
- 附加檔案
-
- Wong_Sir_Grain_Examination_by_Loupe_#3.jpg (159.11 KiB) 已瀏覽 10960 次
-
- Wong_Sir_Grain_Examination_by_Loupe_#2.jpg (256.18 KiB) 已瀏覽 10960 次
-
- Wong_Sir_Grain_Examination_by_Loupe_#1.jpg (138.74 KiB) 已瀏覽 10960 次
最後由 tommy_tse 於 週一 18 6月, 2007 12:34 編輯,總共編輯了 1 次。
天文望遠鏡製作 2007 (第九課-實習課4) 17 June 2007
Here is a picture of how much #600 sands (mixed with liquid soap solution) were being used in a single polishing run.
- 附加檔案
-
- 600_Sands.jpg (259.75 KiB) 已瀏覽 10959 次
誰在線上
正在瀏覽這個版面的使用者:沒有註冊會員 和 18 位訪客