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  #81  
Old 15-05-2018, 04:56 PM
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Lognic04 (Logan)
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Perhaps a custom making scope business could eventuate here. Are we looking at an Aussie Roland Christen here?

Greg.
I hope so!
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  #82  
Old 15-05-2018, 05:45 PM
Stefan Buda
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Awesome Stefan!!! Wish i knew how to make stuff like that!
Logan, when I was your age I also wished to be able to make stuff like that.

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Originally Posted by gregbradley View Post
Wow, this is intriguing stuff. I think we are all somewhat in awe here. You have some super useful skills.

Perhaps a custom making scope business could eventuate here. Are we looking at an Aussie Roland Christen here?

Greg.
Thanks Greg, but you are not looking at an Aussie Roland Christen here, although a small production run of Aussie Made astrographs is a possibility if there is demand. We'll see how the numbers add up after the first one is finished.
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  #83  
Old 15-05-2018, 06:38 PM
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Quote:
Originally Posted by Stefan Buda View Post
Logan, when I was your age I also wished to be able to make stuff like that.


Thanks Greg, but you are not looking at an Aussie Roland Christen here, although a small production run of Aussie Made astrographs is a possibility if there is demand. We'll see how the numbers add up after the first one is finished.
He wasn't always a pro, he started off amateur. Apparently he agonised over the decision to go Pro as you can imagine.

Greg.
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  #84  
Old 15-05-2018, 08:21 PM
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He wasn't always a pro, he started off amateur. Apparently he agonised over the decision to go Pro as you can imagine.

Greg.
I see, yes, I have been agonising about that from time to time over the years.
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  #85  
Old 20-05-2018, 07:21 PM
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One more piece of the jigsaw puzzle done: The camera rotator.
I opted for M68x1 interface thread.
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  #86  
Old 25-05-2018, 07:11 PM
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Cylindrical grinding of the primary mirror inner diameter went well.
I cemented a hefty steel ring to the flat side of the primary, and that allowed me to set it up very accurately in a four jaw chuck.

Today I finished grit 240 (hand grinding), and I'll keep an eye on Logan so he won't win the race.
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  #87  
Old 25-05-2018, 08:06 PM
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Originally Posted by Stefan Buda View Post
Cylindrical grinding of the primary mirror inner diameter went well.
I cemented a hefty steel ring to the flat side of the primary, and that allowed me to set it up very accurately in a four jaw chuck.

Today I finished grit 240 (hand grinding), and I'll keep an eye on Logan so he won't win the race.
Nice!

Hehehe
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  #88  
Old 30-05-2018, 09:03 PM
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I finished grinding the primary and I'll work on other fronts now to give Logan a chance to catch up.

Meanwhile I also made a silicon rubber mould for making the numerous polishing laps needed for the corrector lenses. Small polishing laps are a pain to make without such an aide.

I used plain hardware store silicon rubber that I pumped into the improvised Teflon mould. It would have taken months for the silicone to set all the way through, but I did not have the patience and opened the mould after two weeks. As a result the underside is a bit rough, but the top side squares are smooth and well formed. I haven't used it yet, as the lenses are still at the rough grinding stage.
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  #89  
Old 30-05-2018, 09:08 PM
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Originally Posted by Stefan Buda View Post
I finished grinding the primary and I'll work on other fronts now to give Logan a chance to catch up.

Meanwhile I also made a silicon rubber mould for making the numerous polishing laps needed for the corrector lenses. Small polishing laps are a pain to make without such an aide.

I used plain hardware store silicon rubber that I pumped into the improvised Teflon mould. It would have taken months for the silicone to set all the way through, but I did not have the patience and opened the mould after two weeks. As a result the underside is a bit rough, but the top side squares are smooth and well formed. I haven't used it yet, as the lenses are still at the rough grinding stage.
What?! NOOOOO! The ASI has been a bit of a distraction

Fully finished as in onto polishing or done?

Thats a cool idea to make laps! I assume you use pitch/acculap?

Ive still got time to catch up...

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  #90  
Old 04-06-2018, 09:31 PM
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hi Stefan

Thanks for looping me into this thread - I've had a good read.

Quote:
290 hours of 3D printing went into it so far and another 42 to go


This is some crazy talent and amazing patience and perseverance you have for instrument making. I am in awe but happy to live vicariously through your efforts.. I'll stick to climbing mountains and trucking eclipse gear round the world .

Will be following along your journey now..

Phil
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  #91  
Old 05-06-2018, 03:37 PM
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Originally Posted by philiphart View Post
hi Stefan

This is some crazy talent and amazing patience and perseverance you have for instrument making..

Phil
Thanks Phil, but I can say the same thing about you if I change "instrument making" to astrophotography.
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  #92  
Old 05-06-2018, 03:51 PM
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The third, and hopefully last, iteration of the spider is coming along very nicely. This time it is printed with the carbon fibre reinforced filament.

It looks like the thickness of the vanes will be no more than 1.5mm - better than my earlier estimate of 2mm. If rigidity turns out to be a problem, I will be able to add extra layers of carbon tape and still not exceed 2mm.

The second attached picture shows the milling of a 16mm wide and 0.25mm deep channel in one of the vanes, needed for the FFC ribbon cable.
The milling took two minutes, but the precision fixture required two hours.
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  #93  
Old 05-06-2018, 04:25 PM
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Wow that's amazingly thin. You reckon it's going to be stiff enough?
Second pic got me confused. Which bit in the first pic is it? Looks like an open profile.
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  #94  
Old 05-06-2018, 05:55 PM
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Mark,
I think the shadows in the first picture confused you. There are 8 distinct pieces there and the second picture shows one of the inner sectors being machined.
Regarding stiffness, remember that people make spiders out of piano wires too and you would not describe a piano wire as being stiff. More pictures will make it all clear, but now I have to wait for the FFC ribbon to arrive before I can start bonding tings together. Also there will be another four 3D printed sectors added to the eight shown in the first picture.
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  #95  
Old 08-06-2018, 03:27 PM
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The ribbon cables have arrived and I completed the first bonding stage of the spider. There will be several more stages, but the attached pictures should give an indication of where this is heading.
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  #96  
Old 11-06-2018, 02:10 PM
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Is the ribbon cable for dew removal on the secondary?
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  #97  
Old 12-06-2018, 10:45 AM
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Is the ribbon cable for dew removal on the secondary?
There are 15 lines in the ribbon, rated at 500mA, and I will use 8 for driving the stepper motor. The heater will need no more than 400mA, so I will have enough lines for the temperature sensor and limit/homing switch as well.
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  #98  
Old 12-06-2018, 12:03 PM
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Amazing stuff Stefan , makes my DIY stuff seem rather agricultural

(Thanks very much once again for the DXF, they are getting cut by CALM Aluminium in Minto at the moment. Going with the bolt option)
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  #99  
Old 12-06-2018, 03:11 PM
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Beautiful work ...
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  #100  
Old 21-06-2018, 12:17 PM
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Thanks Matt and Col for the encouragement.

Matt, I'm not sure about agricultural, you seem to do a good job. The approach one takes to ATM is largely determined by the available tools, machinery and metrology.


Meanwhile my progress with the CDK has slowed down a bit - one needs to earn a living too.


I finished 3D printing all the components of the spider and front ring. Next I need to make a large precision jig for bonding the spider to the focuser in such a way that everything is perfectly round and concentric, and the vanes are slightly tensioned when the whole assembly gets bonded to the CF tube.

I purchased a bunch of temperature sensors and had to make the housing myself because the commercially available housed sensors are about 50mm long. Mine are 20.
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