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17" CDK and Equatorial Mounting

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#151 zytrahus

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Posted 28 October 2012 - 12:31 AM

Quick update with the RA bearing blocks:

http://cooledpix.com...bearing-blocks/

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Next I will make the rest of the parts for the RA housing and there is quite a bit of work there =)

#152 angusb1

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Posted 28 October 2012 - 01:43 AM

Hi Stephen,

I've been following your build over the last few weeks and you're coming to the part I find particularly interesting now, the building of the equatorial mount. I hope you don't mind me asking what size shafts/bearings you're using? Also, will the shafts be solid or hollow, and what kind of bearings are those?

Fascinating build, thanks for sharing it in such detail.

#153 zytrahus

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Posted 28 October 2012 - 06:49 PM

Thanks Angus, these are tapered roller bearings the bigger one is 150 mm OD and the smaller one is only ~130 mm. Both RA and DEC shafts will be hollow and about 110 mm to the front and 90 mm to the rear.

#154 angusb1

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Posted 29 October 2012 - 07:10 AM

Thanks Stephen.

#155 123456

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Posted 30 October 2012 - 01:04 AM

great thread stephen

just wondering how are you setting the pre load on the bearings ?

joe

#156 zytrahus

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Posted 30 October 2012 - 01:38 AM

preload is done with a preloading plate (made of thick SS) that is bolt on the rear of the shaft in 6 points (60 degrees apart). The front of the shaft is shouldered to sit on the inner ring of the front bearing.

#157 coinboy1

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Posted 30 October 2012 - 06:18 AM

I have to say this build is amazing and inspiring. I have dreamed of using CNC equipment to build a scope such as this. Your engineering and machining skills are excellent. I am loving it. :)

#158 Baxstar

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Posted 30 October 2012 - 12:35 PM

Where can i order? No just kidding, really like your project and I will be following it!

Casper

#159 zytrahus

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Posted 26 December 2012 - 07:55 PM

It's already been more than 1 months since I have put more work on this but unfortunately, I've had a real busy end of year and I am hoping I will be able to make more parts early 2013.

One good news though, the optics for the CDK are being made and I should have them in 3 months!

#160 zytrahus

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Posted 04 April 2013 - 06:21 PM

Quick updates, I haven't had a chance to make any other part, 2013 has been busier than expected but I have good hopes for the next few weeks!

The optics are almost finished (probably a couple of weeks + another 4 weeks for surface shipping)!

Also I am hoping to move to the mountains (mount Pinot area, CA) toward the end of the summer, where I'll finally be able to build a small observatory.

#161 zytrahus

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Posted 29 April 2013 - 10:38 AM

Last night, I adjusted both motor/worm block assemblies for a perfect contact between the two pinions. And I also worked on temporary wiring for the motors/encoders to test both motor assemblies on the Gemini-II controller. I should be done tonight. Selecting motors that would work with this controller was kind of challenge considering the current limitations of the IC's but it should work!

I've also sent out the RA shaft for manufacturing, all the lathes I could use for this were just too small. I've got an ETA of 2 weeks for the shaft, meanwhile I'll try to finish the RA housing (several CNC parts) as well as the DEC housing which needs to be installed at the end of the RA shaft before it's assembled on the mount.

#162 zytrahus

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Posted 02 May 2013 - 10:46 PM

I just finished interfacing my maxon motors/encoders to the Gemini-II controller.
It was a little tricky as some electronics (line receivers/comparators) but it works!
Everything was done on test boards, I am going to make a couple of PCB for a more compact/reliable interface.

#163 zytrahus

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Posted 03 May 2013 - 03:50 PM

1 motor and 1 worm in action: http://www.youtube.c...h?v=1b9FS-6H2M8

#164 zytrahus

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Posted 20 May 2013 - 11:38 PM

Here's the RA shaft :)

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http://cooledpix.com.../eq-z-ra-shaft/

#165 Escher

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Posted 21 May 2013 - 07:55 AM

I had all but forgotten about this beauty! Thanks for reminding me!

Awesome work thus far - Cant wait to see the finished product!

#166 zytrahus

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Posted 22 May 2013 - 11:15 PM

Thank you sir :)

I'm making some modifications to the rear end cap of the RA shaft by adding a high resolution shaft encoder (resolution of 0.41 arcsec). It doesn't change things much especially as I had not made any of these parts yet. The encoder will probably not be initially supported by the controller but it should at some point :)

#167 zytrahus

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Posted 26 May 2013 - 01:45 AM

Here's some pictures of the PCB I had to make to interface the motor/encoder's to the Gemini-II controller.

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more information on this page: http://cooledpix.com...otor-interface/

#168 zytrahus

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Posted 27 May 2013 - 12:30 AM

And here's a recent screenshot of what the final product will look like (new Dec housing - easier for me to machine than bigger turned parts, clutch window on the RA gear cover, rear cap on the RA axis hosts a high res renishaw encoder, and that's about it)

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#169 Mirzam

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Posted 27 May 2013 - 06:53 AM

Looks really nice! You might want to use a beefier dovetail saddle design. For example, Astro-Physics uses something called a P-style or Planewave style saddle and dovetail design.

Astro-Physics

JimC

#170 zytrahus

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Posted 27 May 2013 - 10:01 AM

Thanks for the link Jim. I've been thinking of doing something to the saddle for some time now, it's a good suggestion.

#171 zytrahus

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Posted 01 June 2013 - 12:25 AM

I can't do exactly an AP saddle but I was able to do something substantially stronger, I'll have to re-machine a dovetail for the scope but I needed one of them to be longer anyway (to have a little bit of freedom to adjust the balance).


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#172 zytrahus

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Posted 17 July 2013 - 11:59 PM

I'm updating this thread real quick...
Currently in the process of moving to a new home where I'll have the observatory for this project. Still waiting on the optics, final figuring has been taking longer than expected apparently.

I am in the process of finishing the parts for the RA housing.

Cheers

#173 s800

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Posted 18 July 2013 - 09:13 PM

Really fantastic to read this- thanks for the details and the pics.

A couple questions:

What goes in to bearing selection? I'm not at versed in bearings and am curious how one selects a bearing that won't introduce errors in tracking.

What type of problems (if any) have you had going from Solidworks->Real world? Is the workflow really Solidworks to CNC and everything truly fits together?

Thanks! Amazing build

#174 zytrahus

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Posted 19 July 2013 - 01:03 AM

Hi and thanks for the kind words!

I went with high quality tapered roller bearings which should be adequate, practically I don't know yet if this was a good choice or not.

In terms of translating CAD work into actual parts, I spent a bit of time making sure dimensions and tolerances would be adequate and then it's a question of respecting this during the manufacturing process. Luckily I have some experience here and so far everything's been working fine. But it's far from complete.

#175 zytrahus

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Posted 02 August 2013 - 12:47 AM

super quick update. I've anodized the 2 rolled aluminum gear covers (for RA and DEC) as well as the RA shaft.

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Also I am moving to my new house this week-end. I was there last night to drop some stuff. The last 10 miles are absolutely dark (blue zone) - we could make out the Milky-Way looking through the driver side window of my car... I knew skies were good (kind of why we chose this area) but that good? wow. I never had the chance to test the skies before moving! I'll be imaging from there this week end with my wide field setup. Anyway kind of off topic just to say that I'll start working on the observatory shortly also!


Cheers






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