Telescope Reviews: 17" CDK and Equatorial Mounting

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gregj888
sage

Reged: 03/26/06

Loc: Oregon

Re: 17" CDK and Equatorial Mounting new

[Re: gregj888]
#5420348 - 09/14/12 02:21 AM

Benach

No worries, I wasn't looking for you to do the work, just courious about the more complex modeling.

Thx,

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MKV
Carpal Tunnel

Reged: 01/20/11

Re: 17" CDK and Equatorial Mounting new

[Re: gregj888]
#5420458 - 09/14/12 06:20 AM

Quote:

I agree, though think of it differently. Tilt of a spherical surface can be though of as decentering. The reason I down play this it that it's the only alignment issue theat's fairly easy to see and correct (with a laser colimator). This is also in contrast to an asphere, that is down right ugly... tilted or decentered :-)

Aspherics are much more difficult, no argument there. I only illustrated that even a small tilt of one element in a DKC will degrade the image and make it unacceptable. And in a DKC you are not dealing with one element but with four - the secondary mirror, the corrector lenses and the corrector itself as a unit. Lots of trial and error repetitions to get it collimated for visual use. But this is off topic, so I am out of here.

Regards,

Mladen

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: MKV]
#5431994 - 09/21/12 12:21 AM

Quick update with the assembly of the first few parts of the equatorial mounting.

http://cooledpix.com/2012/09/20/eq-z-base/

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David Pavlich
Transmographied

Reged: 05/18/05

Loc: Mandeville, LA USA

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5432273 - 09/21/12 08:42 AM

Looks like some dandy hardware!

David

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5433307 - 09/21/12 07:21 PM

Quote:

I was hoping I could assemble the secondary tonight but I had to rework a few threads that were a little too tight! Guess the complete mock-up will be finished tomorrow.

I started another thread looking for help on Truss Tube Ends. Are these something you made at home or found somewhere where a rank ATMer like me could procure them?

FWIW, I will be working with 1.25 inch OD Aluminum Tubes to fashion a 300MM F20 DK.

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: Tom and Beth]
#5433323 - 09/21/12 07:31 PM

I couldn't find anything off the shelf so I ended up making them.
If I am not mistaken Moonlite makes some truss components but I am not sure if they would be suitable for your project.

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5433335 - 09/21/12 07:39 PM

I was a fraid you would say you made your own. I have seen Moonlights, and if nothing else their articulated double end (for lack of a better description) looks promising.

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droid
rocketman

Reged: 08/29/04

Loc: Conneaut, Ohio

Re: 17" CDK and Equatorial Mounting new

[Re: Tom and Beth]
#5433389 - 09/21/12 08:13 PM

Scope looks beautiful....best of luck on ,it.....
and David your doing a good job moderating this thread.

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Escher
scholastic sledgehammer

Reged: 08/30/07

Loc: Fenton, MI

Re: 17" CDK and Equatorial Mounting new

[Re: droid]
#5433450 - 09/21/12 08:58 PM

Beautiful work Stephen!

As a side note - I have been considering learning SolidWorks - are you self taught? I'm watching this thread with much interest, not only because of the workmanship, but as a FEA / CAE professional I'm interested in the discourse.

At the risk of being mentally pummelled by other ME's who know much more about the topic than I...

If there is too much flexure - it would seem that you could simply add a second upper ring, with multiple attachment points to effectively double or even triple your stiffness with the right beam section. With your skills, I would think this would be a pretty simple addition.

Looking forward to seeing more progress!

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: Escher]
#5433692 - 09/21/12 11:57 PM

Hi Escher,
I did some Solidworks in School but most of the Mechanical design and analysis courses were based on Catia V4 initially then V5 and some FAE under Nastran. That was already over 10 years ago and for the past 7 years I've only worked with Solidworks with minimal FEA as most of my professional work is thermal/fluids i.e. CFD analysis.

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5451249 - 10/02/12 01:25 AM

Really small update with the assembly of the 2 motor/worm assemblies:

pinion/spur should be there soon to complete the drive system.

I've also made the Alt / Az adjustment bolts/barrels/knobs.

Next I think I am going to start working on the tougher work with the RA housing...

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polaraligned
professor emeritus

Reged: 12/26/08

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5451388 - 10/02/12 06:35 AM

Is that black paint or anodize? Looks like paint in the pictures. Very nice job.

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: polaraligned]
#5451741 - 10/02/12 11:32 AM

it's anodizing like the other parts, this point and shoot camera is doing way too much sharpening

(and i always sand blast the parts before anodizing)

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Steen27
sage

Reged: 05/26/06

Loc: Torrance, CA

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5454128 - 10/03/12 08:21 PM

Thank you very much for sharing your work and pictures of your project - it's very inspirational.

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johnC
member

Reged: 08/24/06

Loc: Hucknall Nottingham UK

Re: 17" CDK and Equatorial Mounting new

[Re: Steen27]
#5454495 - 10/04/12 02:13 AM

Continues to be a fantastic thread.
My wife and I are facinated with the progress of this project. As Jim said...very inspirational.

John

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: johnC]
#5454527 - 10/04/12 02:50 AM

John, Jim, thank you very much!

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David Pavlich
Transmographied

Reged: 05/18/05

Loc: Mandeville, LA USA

Re: 17" CDK and Equatorial Mounting new

[Re: zytrahus]
#5454716 - 10/04/12 09:02 AM

That's some nice work!!

David

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drollere
Pooh-Bah

Reged: 02/02/10

Loc: sebastopol, california

Re: 17" CDK and Equatorial Mounting new

[Re: David Pavlich]
#5455263 - 10/04/12 03:21 PM

stephen, three comments.

i am completely gobsmacked by the beauty and ambition of your project. i have to say some emotion between laughter and tears overtakes me when i remember the 6" telescope i made as a teenager with my father, using plumbing joints and babbitted bearings after the instructions in thompson's book. how things have advanced!

i am really pleased you chose a dall kirkham, a scope design that i thought was unfairly reviewed in a recent optical handbook, and look forward to details of your optical specs, optical supplier, and reasons for your choices of both.

i want to complement you on your maturity and poise. you know what matters and what doesn't in the path to get where you are going ... which is a rare thing in my experience. the fact that you also have the generosity to document your work here is just the icing on the cake.

good luck and keep posting!

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zytrahus
professor emeritus

Reged: 06/16/09

Loc: Long Beach, CA

Re: 17" CDK and Equatorial Mounting new

[Re: drollere]
#5455837 - 10/04/12 10:20 PM

Thank you very much for the kind words, Bruce.

I hope to be able to get the optics soon... as I can't wait for the first light! But there is still quite a bit of work ahead.

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Chucke
member

Reged: 03/12/10

Re: 17" CDK and Equatorial Mounting [Re: zytrahus]
#5456917 - 10/05/12 05:51 PM

Hi Zytrahus,

I see you are in So Cal. Are you a member of OCA?

Chuck

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