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Post by jamesling1000 on Sept 23, 2011 3:15:15 GMT -5
Hi All. Is almost 3 weeks since I brought back my 8" Istar F8.8 for some modification. First week was spent just to deliver the 8" tube , without the counter cell , to another country whereby I am working there. 2nd week was for sending and returning the modified 8" tube , to my machinist. 3rd week, which is this week, was spent to deliver back the 8" tube back to my country. So this weekend when I am back home, I'll assemble it back, and if possible test it on my losmandy gemini 2 . Hope the weather is not like the last 2 weeks, is cloudy and raining all the times. Will show the simple attachment I made to connect the 2 cut ends of the 8" tube. Regards James Ling Attachments:
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Post by borispider on Sept 23, 2011 3:44:20 GMT -5
Can't wait to hear the results
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Post by jamesling1000 on Sept 24, 2011 5:35:17 GMT -5
Hi ALL. just returned today, and immediately opened up the ctn, delivered to me while I am away.... Attachments:
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Post by jamesling1000 on Sept 24, 2011 5:43:17 GMT -5
The tube was cut at 36inches from the rear, and mounted back with a connecting sleeve, using 5 mounting screws from both ends of the cut tube... Attachments:
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Post by jamesling1000 on Sept 24, 2011 5:47:48 GMT -5
After checking the assembly, I reassembled the front end of the tube with the connecting sleeve, and some enlarging of the tubing holes are required as the machining is not done accurately. Attachments:
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Post by jamesling1000 on Sept 24, 2011 5:51:55 GMT -5
Next is to assembled the front tube to the counter cell... And this is the most difficult portion to assemble, coz a total of 4 parts are required to align and asm with 5 screws. This is the 2nd time I am doing, but there is no easier way or method if you want to remove and asm this parts to save storage space.... Attachments:
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Post by jamesling1000 on Sept 24, 2011 5:54:58 GMT -5
The final assembly of the rear tube to the front tube , together with the counter cell is very simple. Just put the front tube in an upright position, with the counter cell facing down, then slot the rear tube over the front tube...... This step will be the only step I need to do , when I do my side walk in future..... Attachments:
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Post by jamesling1000 on Sept 24, 2011 6:00:50 GMT -5
Once the 5 screws are mounted to secure the rear tube to the sleeve...., the 45lb OTA, is ready to use, by mounting the mounting rings , then onto my losmandy mount. The very last time I disassemble and assemble the OTA, the collimation is still not affected.... This time, with 2 sections of the OTA being assembled, will see how well is the collimation ...... Hopefully this weekend I am able to setup for star test.... Regards James Ling Attachments:
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Post by Mike on Sept 24, 2011 12:20:56 GMT -5
I think you have a great idea James. The collimation is my only concern. If that turns out well, you got a winner.
Mike
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Post by mikey cee on Sept 24, 2011 16:54:57 GMT -5
James....Do you have an index mark on the two tubes and the sleeve also?? Also do you have any problems with dust and dirt getting on the backside of the lens? I like the idea of being able to get at any dust flecks. It has always drove me crazy when I spotted a piece of dust on the backside of my 8" Brandt. I had to always wait 'til the next "cleaning date" which could be 5 years or more for me. ;D ;D Mike
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Post by jamesling1000 on Sept 25, 2011 8:07:29 GMT -5
James....Do you have an index mark on the two tubes and the sleeve also?? Also do you have any problems with dust and dirt getting on the backside of the lens? I like the idea of being able to get at any dust flecks. It has always drove me crazy when I spotted a piece of dust on the backside of my 8" Brandt. I had to always wait 'til the next "cleaning date" which could be 5 years or more for me. ;D ;D Mike I did not do any marking for the cut tubes and sleeve, as I have the sleeve made 4" long, and is sliding fit, not the way ISTAR mfgs the counter cell assemble retaining split ring, which is loose. As for dust, yes, even I use the orion dew shield to wrap the counter cell 5 opening holes.. when I store it (refer to attachment photo), with pkgs of silica gel.... But for this opening vents design, is very easy to do lens cleaning, even after storing it for almost 5mths, without using it. REgards James Ling Attachments:
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Post by jamesling1000 on Oct 15, 2011 7:23:10 GMT -5
Hi All. This is another update from the progress of my 8" ISTAR OTA modification..... 1. This attachment photo show a new and longer dove tail I fabricated, as the smaller one I used previously is for my 10" Mewlon. This is the one that took me another week to ensure it matches the spacing that I specify..... Regards James Ling Attachments:
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Post by jamesling1000 on Oct 15, 2011 7:26:38 GMT -5
2. I attached the Orion laser collimator, to check the alignment of the assembled cut tubes as well as the tube and counter cell assembly. continue..... Attachments:
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Post by jamesling1000 on Oct 15, 2011 7:31:33 GMT -5
3. This is the laser that is seen from the other end of the lens side.... Physically I examined it, and it appears quite central this time..... Otherwise I will need to loosen the 5 mounting screws that secure the tube to the counter cell.....(The 4 part assembly is a bit of loose fitting....) and retightening it again.... continue..... Attachments:
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Post by jamesling1000 on Oct 15, 2011 7:34:52 GMT -5
4. After the OTA assembly is completed, I set up my losmandy G11 G2, with the dovetail adjusted to the VERTICAL POSITION, so that I can mount the 60 lb 8" ISTAR to me myself ( I am doing it alone ) continue... Attachments:
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