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34" F2.89 Large Fork Mount BHMO Project Build

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#1 ctcables

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Posted 05 September 2016 - 03:20 PM

I have been working on the below listed project for about 6 months but the idea started during OSP 2015.  Because I have enough work completed and some photos I can now post I wanted to start a post to share my work and receive constructive good or bad feedback. 

BHMO Black Hole Mobile Observatory is a project to build a mobile 34” telescope that can be used at events all over the NW.
Project Goals
1. Obtain 34” Primary Mirror blank.  DONE
2. Have mirror blank cut in half.  DONE
3. Generate mirror blanks, one at F3.3 and the second one to be at F2.87 DONE
4. Have Fused Silica mirror blanks shipped to Mike Lockwood DONE
5. Design telescope based on the 34” by 2.3 inch figured to F2.89 INITIAL DRAWING DONE
6. Start to gather parts to build telescope Working on this
7. Find a 7.75 secondary 8 Inch cellular found. 8" cell DONE
8. Get Secondary polished and coated.
9.  Create Facebook page to track project progress.  DONE
10.  With the support of RCA Work Shop http://www.rosecityastronomers.org/ start construction.
11.  Work on Drive system with the help of Dan Gray sidereal technology
Alt bearing and Dec bearing found. Done
Make Direct drive motors, working on coils now.

ATM EXPEARINCE:
First real telescope Mead 10” Reflector 1998
Built 12.5” Reflector using recycled parts 2000
Built Carbone Fiber supper light Reflector 31lbs 14.5” fused Quartz Mirror, Link to OSP http://bbastrodesign...eWalkabout.html
Built Carbon Fiber 20” super light reflector Link to Oregon Star Party OSP Walkabout.
http://bbastrodesign...eWalkabout.html

Face Book Page information https://www.facebook...=PAGES_TIMELINE
Link to my 20" telescope build http://www.cloudynig...-carl-z-mirror/
PLANED USE OF THE BHMO:
High Schools and collages located in the North Western United States
RCA Rose city astronomy public star party’s
OMSI Star Party’s
Oregon Star Party
Privet Party events
Research trips for students

I have added some photos below and will add updates as time moves along.

Attached Thumbnails

  • 34 rev 3.jpg
  • 18pt cell.jpg
  • grind.jpg
  • blank before.jpg
  • blank spec.jpg
  • dem.jpg

Edited by noisejammer, 19 December 2016 - 11:07 AM.
requested by OP

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#2 ctcables

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Posted 05 September 2016 - 03:29 PM

Some more photos of parts and work completed.  Mirror cell, Direct Drive motor coils, and 80/20 fork frame parts.

Attached Thumbnails

  • 80-20al.jpg
  • coilsdone.jpg
  • cleaning parts.jpg
  • slice.jpg

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#3 ctcables

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Posted 05 September 2016 - 03:30 PM

Primary cell

Attached Thumbnails

  • mirrorcell34.jpg

Edited by ctcables, 05 September 2016 - 03:31 PM.

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#4 ctcables

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Posted 05 September 2016 - 03:35 PM

First photo is of a sample for mirror edge support, second is of the CDK fork mount direct drive and the third is of another fork mount that inspired me to use the 80/20 for the frame.

Attached Thumbnails

  • bigblue3.jpg
  • planewaveCDK.jpg
  • forkmountj.jpg

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#5 ctcables

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Posted 05 September 2016 - 03:42 PM

Making of the lower Mirror box which will not be a box. I had to make a drum as I could not find anything that was round at 38" OD to wrap the carbon fiber around. The first layer turned out fairly well and I think will work out great.  I have a vast amount of work left to do and would like to finish up in a year or so but we will see how it moves along.

Attached Thumbnails

  • cutcarbon.jpg
  • drum 38 inch.jpg
  • drumwraped..jpg
  • Rings.jpg
  • carbonwrap.jpg

Edited by ctcables, 05 September 2016 - 03:51 PM.


#6 mark cowan

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Posted 05 September 2016 - 04:29 PM

Wow, Chris, thanks for sharing all this - the project may be enormous but I have no doubt you can carry it off.  :waytogo:


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#7 brucesdad13

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Posted 05 September 2016 - 05:32 PM

Love it! Giving me motivation to start cutting the big piece in my garage. :)

#8 ctcables

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Posted 05 September 2016 - 05:55 PM

Wow, Chris, thanks for sharing all this - the project may be enormous but I have no doubt you can carry it off.   :waytogo:

I am sure it will get done but unlike the 20" there will be no lifting it over head, LOL.


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#9 mark cowan

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Posted 05 September 2016 - 08:14 PM

At least you can ride on it, right? :lol:


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#10 polaraligned

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Posted 05 September 2016 - 09:10 PM

Very nice, and good luck.

I am very interested in learning more about the direct drive motors.  I followed all the early builds of these motors that were published. 


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#11 jdownie

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Posted 06 September 2016 - 03:43 PM

First photo is of a sample for mirror edge support, second is of the CDK fork mount direct drive and the third is of another fork mount that inspired me to use the 80/20 for the frame.

Hi Chris,

 

Do you have a link to the fork project - it seems very interesting.

 

John



#12 jtsenghas

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Posted 06 September 2016 - 04:48 PM

Impressive project, and well underway! 

 

I'm curious about the primary cell.  What is the construction? The components appear to be carbon fiber over a core I can't identify. 


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#13 ctcables

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Posted 06 September 2016 - 05:34 PM

Impressive project, and well underway! 

 

I'm curious about the primary cell.  What is the construction? The components appear to be carbon fiber over a core I can't identify. 

Carbon Fiber over Nomax core which is used in plains and NASA, it is a fiber material that absorbs the epoxy and becomes very stiff but light and when combined with the top and bottom layer of carbon fiber it is hard to beat. I have added a better view of the layers and also added a better photo of my 8" secondary.

Attached Thumbnails

  • nomax.jpg
  • cellsecondary.jpg

Edited by ctcables, 06 September 2016 - 05:39 PM.

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#14 ctcables

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Posted 06 September 2016 - 05:44 PM

 

First photo is of a sample for mirror edge support, second is of the CDK fork mount direct drive and the third is of another fork mount that inspired me to use the 80/20 for the frame.

Hi Chris,

 

Do you have a link to the fork project - it seems very interesting.

 

John

 

this is the link http://www.cloudynig...y-fork-project/



#15 ctcables

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Posted 03 November 2016 - 01:42 AM

Making some more progress with the base.

Attached Thumbnails

  • Base with bearing brace..jpg
  • carbon2.jpg
  • bace 3.jpg

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#16 Mike Lockwood

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Posted 03 November 2016 - 11:51 AM

I like your use of the extrusions in the cage structure instead of hollow tubes.  It makes it very easy to attach things.

 

I am making good progress on the primary.


Edited by Mike Lockwood, 03 November 2016 - 11:51 AM.

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#17 Tyson M

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Posted 03 November 2016 - 01:11 PM

I am now following your project via Facebook. 

 

Awesome project. 


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#18 555aaa

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Posted 03 November 2016 - 02:32 PM

Very impressive project.

 

What are you using for the encoders for the direct drive? I think some big projects have been using the Renishaw encoders (20 micron pitch / 20 nanometer resolution) but I think they are very expensive.



#19 ctcables

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Posted 03 November 2016 - 05:26 PM

I like your use of the extrusions in the cage structure instead of hollow tubes.  It makes it very easy to attach things.

 

I am making good progress on the primary.

Received the secondary, need to send it to Tom now. Good to hear the primary is going well. I still have so much work to do on my end but will keep plugging away at it.  Thank you for the update.



#20 ctcables

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Posted 03 November 2016 - 05:29 PM

Very impressive project.

 

What are you using for the encoders for the direct drive? I think some big projects have been using the Renishaw encoders (20 micron pitch / 20 nanometer resolution) but I think they are very expensive.

yes very expensive but seems to be the best option, working with Dan Gray who is helping me get the direct drive motors working properly. Currently the main bearings are out for machining.



#21 ctcables

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Posted 15 November 2016 - 11:28 PM

Photo of inside carbon fiber and second photo is of the nomax wrap around it.  Need to add one more layer of carbon then layer of nomax and complete with outer carbon fiber. This will make a very strong cage for the 140 lbs mirror.

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  • nomax.jpg
  • insidecarbon.jpg

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#22 mconnelley

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Posted 16 November 2016 - 01:51 AM

Hello:

 

   I curious as to why you decided to go with a round shape for the bottom part of the scope.  I would think that a round shape makes a lot of the geometry more complicated than a square bottom end.  

Cheers

Mike



#23 Eikonal

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Posted 16 November 2016 - 09:18 AM

Wow!

 

The figuring the lightweighted secondary alone is quite a task, I bet!

Is that a custom blank made to order, oder is that a standard part?

If so, where did you get it from?

 

All the best,

Kai.


Edited by Eikonal, 16 November 2016 - 09:18 AM.

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#24 brucesdad13

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Posted 16 November 2016 - 01:16 PM

Ditto what Mike said. :) Maybe when I build my next 3d printer I'll order extra extrusion....

 

I like your use of the extrusions in the cage structure instead of hollow tubes.  It makes it very easy to attach things.



#25 ctcables

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Posted 16 November 2016 - 03:34 PM

The secondary was a custom order from Hercules Telescopes in Canada made the secondary and it will be finished by Mike Lockwood and Carl Zambuto will do the coating. as to the round bottom it seems to work best for a fork mount.


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