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Stargate 600S Rebel (SW500P rebuild)

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#1 Arctic eye

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Posted 15 April 2019 - 03:15 PM

Hello everyone!

 

Maybe it is time to start an own thread for this Building Project. I wasn't supposed to start this Project, but destiny (or Synta) decided otherwise… So first some background.

 

 

This all started in 2016, when I decided to buy a SkyWatcher Stargate 500P. I had been doing succesfull L&P imaging with my SW400P for years and SW300P before that, so I was anticipating similar decent quality of optics.

 

SW500ulkona1.jpg?img=full

 

 

But after almost a year of unsuccesfull attempts to get even one decent capture, I realised it's not the seeing. I set up both my old SW400P and the 500P side to side and made a comparison by switching my imaging train from scope to scope in turns for multiple times in consequent evenings. Results were clear; SW400P performs, but 500P not. Not even when apertures were masked equal. Stacked comparison images below. 

 

400p_500p_comparison.gif?img=full

 

Platoncomparison.gif?img=full

 

 

 

 

Something was wrong and it was not collimation, so I started to do star testing. That revealed a bad print-through in the mirror and also some correction problems.

 

Startest_Dubbhe_16032018_80.jpg?img=full

 

 

I did a reclamation to my vendor, who started a process with the European distributor, who again contacted the factory. It took 8 months to get a new tested replacement mirror from the factory. I was angry because of the slow process, but happy to get a new mirror and have the problem dealt with. Or so I thought…  When finally there was some clear weather, I star tested the new mirror and found it to be even worse. It had similar print-through, but now also astigmatism and even worse correction problem:

 

Capella_10w.gif?img=full

 

SW500peili1.jpg?img=full

 

 

 

 

It was clear that Synta was not able to deliver anything decent and my vendor had disappeared during the process. So whatever I would try there, it would take a long time again and end result would be unsure. I decided I would need a new mirror from somewhere else. And if I do that, why not order a bigger mirror while I'm at it... 

 

 

 

And here my story really begins: I have this Stargate 500P from which I am going to salvage the goto base, focuser and some other parts. Faulty optics and rest of the parts I will propably donate to some local astronomy club. Then I will need to modify the goto-base wider to accept the new bigger OTA I will build. And new 600mm F4 optics from Nicholl Optical, already ordered, to be used in that OTA. So it's all or nothing now! Let the story begin and hope there is a good end in this story smile.gif

 

500p2.jpg?img=full


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#2 Arctic eye

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Posted 15 April 2019 - 03:30 PM

It all starts with the mirror cell. I decided to do a 27 point cell and designed with PLOP:

 

 

 

Colour%20plot1.jpg?img=full27cell.jpg?img=full

 

 

10mm aluminum plate for the triangles. Tried with spherical bearings first, but found them too sticky, so switched to acorn nuts on the fly.

 

cell1.jpg?img=fullKolmiot1.jpg?img=full

 

cell3.jpg?img=full

 

Whiffletree edge supports with POM-plastic bearings. Angle of whiffletree is adjustable.

cell6.jpg?img=full

 

 

 

I made a dummy mirror from an old kitchen desk board to test and adjust everything.

cell4.jpg?img=full

 

 

Dummy mirror is 27mm thick, while actual mirror will be 46mm

 

cell5.jpg?img=full


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#3 Arctic eye

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Posted 15 April 2019 - 03:41 PM

Painted the stainless steel mirror cell frame. Started to weld frames for the mirror box from aluminum.

 

 

Mirrorbox1.jpg?img=full

 

 

 

 

Two aluminum frames wrapped with 4mm aluminum plate, and the 700x700x300mm mirror box starts to have shape

 

mirrorbox2.jpg?img=full

 

 

 

 

Rockers from SW500P bolted into the mirror box. Pretty good parallelism achieved with some shimming. Also welded 10mm aluminum plates to the top corners for truss tube joints.

 

Mirrorbox3.jpg?img=fullMirrorbox4.jpg?img=full


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#4 Arctic eye

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Posted Today, 02:42 PM

Finally had some time to continue this Project. Started to build the UTA ring, or actually UTA octagonal.

 

First cutted the aluminum parts:

 

UTA1.jpg?img=full

 

 

 

 

Then some welding and it came out really sturdy. Just need to weld the fixing plates for the trusses and for the focuser plate and drill holes for secondary vanes. I will use the focuser plate and focuser from SW500P.

 

Uta2.jpg?img=full  Uta3.jpg?img=full

 

 

 

The new optics already arrived 3 weeks ago from Nichol Optical, as promised. It was packed really well and the mirrors look goooooood!

 

Mirror1.jpg?img=full  Mirror2.jpg?img=full

 

 



#5 Arctic eye

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Posted Today, 03:02 PM

Also, I have now agreed to donate the optics and leftover mechanical parts of the original SW500P Dob to a nearby deeb sky observer. He will attempt to make a 500mm low-power light bucket Dobson out of it! So one very disappointing scope is now turning into two new joyous scopes!




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