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Newton 16" F4,5 Carbon fiber...all

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#1 CanaryMax

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Posted 07 February 2015 - 03:36 PM

Hello:

 

It has been a while since building my previous telescope, newton 8 "f5.

http://www.cloudynig...= carbon fiber

 

Now I throw myself to the construction of what I hope will be my last telescope, assuming that my illness is cured to large mirrors.

 

Like the previous project is a telescope made entirely of carbon fiber, epoxy resin and stainless steel screws.

Solid fiber parts, using techniques of bulk molding compound, fiber mixed with resin to form a moldable mass under pressure.

I'm still at a fairly early stage and I hope to completing this thread slowly, probably take several months to finish the project because I do not have the necessary time,

unfortunately I have to go to work on Monday ...

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Edited by CanaryMax, 07 February 2015 - 03:40 PM.

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#2 glend

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Posted 08 February 2015 - 05:39 PM

I will follow this with interest, having just completed a 10" imaging newt using carbon fibre struts with plywood rings. I have a 16" dob that I would like to convert to an imaging newt and carbon fibre is the only reasonable way to save enough weight to be able to handle it. Good luck. Can you give us the details on the carbon fibre sources and resins that you will use as you go along? thanks



#3 starman345

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Posted 08 February 2015 - 06:03 PM

 

Now I throw myself to the construction of what I hope will be my last telescope, assuming that my illness is cured to large mirrors.

 

 

Famous last words :grin:  I too will be watching this thread with interest.



#4 jonathanCR

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Posted 10 February 2015 - 12:14 PM

using techniques of bulk molding compound, fiber mixed with resin to form a moldable mass under pressure.

 Can you provide a link or a description to this process please. 



#5 CanaryMax

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Posted 11 February 2015 - 05:16 AM

Hello:

 

Glend:  

These are the data of the fiber and resin've used so far.

 

- L Resin and L Hardener of this document: http://www.ezentrumb...d_en_100135.pdf

 

- Fiber bulk molding compound:

 

Density 1.76 g / cm³, filament diameter 7 microns epoxy-preparation 1.3%, bulk density 400 g / dm, tensile strength 4000 MPa, tensile modulus 238 GPa, elongation at break 1.7%.

 

- Fiber to the outer laminate:

 

Fibre: Tenax, Torayca or Pyrofil 3k-yarn

Style 452
Twill weave
Width 100 cm
Setting Thr/cm: 5 x 5

Resin consumption: 234 g/m², laminate thickness: 0.327 mm, laminate weight: 438 g/m²

 

Jonathan JR:

The truth is, I do not find examples of Bulk molding compound homemade, I have not looked too.
If you do a search on google with "Bulk molding compound" or "Press moulding compound", you will find a lot of information on how this is done industrially, an example is this:

http://www.hexcel.co...es/IHexMC-Video

 

Regards

Maximo


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#6 NickK-UK

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Posted 11 February 2015 - 07:52 AM

I'm actually planning the build of a 18" f4 truss newton (about 12Kg for the primary mirror).

 

One the issues I see with using the mirror cell made of carbon fibre is that the fibre needs to be laid in such a way align the strength again the force (rather than using just the epoxy strength). So would you look at using a U section to prevent bending?

 

I don't know if you've seen Ray's design? (purely for inspiration!)

https://www.flickr.c...02/12263153285/


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#7 CanaryMax

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Posted 11 February 2015 - 11:50 AM

Yes, I think that a section in the form of U would be rather more efficient to avoid flexing in the cell, it is a matter that I still have hands if modify that triangle which support the three triangles of the primary mirror support (9 points) and strengthen U-shaped as you say.
It's one of the benefits of fiber, which can change many things half-built and as I have not cut the bars can decide many changes.

 

Yes, I knew Ray design, but I'm stubborn and want to do it all circular clamping rings.


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#8 Alex Parker

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Posted 16 February 2015 - 08:45 PM

I will follow this with interest, having just completed a 10" imaging newt using carbon fibre struts with plywood rings. 

Planning on posting some info on your build?



#9 CanaryMax

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Posted 17 February 2015 - 09:18 AM

Hello again:

Last week I continued making parts of the telescope, this time it is the front tube that supports the spider and the focuser.

I used fiber 400gr / m2, two inner turns, aramid honeycomb 5mm for the core and two outer turns of 400gr / m2.

I post the picture of the finished tube, there are more images of the process on my website.

http://canaryastro.w...lbumid=15819330

 

Regards

Maximo

 

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#10 CanaryMax

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Posted 08 March 2015 - 01:15 PM

Hello:
The lack of free time does not allow me much progress in the project, I could only make the second ring and prepare stainless steel balls for bars.

 

Well, it has also given me time to become a mini Millennium Falcon with some leftover fiber. you can find it?

 

I'm thinking of doing the rotatable top tube for easy visual observation, so it'll take a while to move the project when you have decided as I do.

 

The pieces are placed only with double-sided tape to go forward seeing nothing better to do as it is becoming to encourage me to continue.

 

Regards

Máximo

 

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#11 CanaryMax

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Posted 07 September 2015 - 05:10 AM

Hello:
A few months later ... I've hardly been able to continue with the project because of health problems in my neck and back which fortunately I'm better.
I could finish the back truss tube and front tube.
I have to redesign the cell as the primary mirror will be conical.

 

 

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#12 JM La Galette

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Posted 18 September 2015 - 02:16 PM

Max,

 

Can you tell where did you manage to find a 16" conical mirror?

 

Thanks,

JM



#13 CanaryMax

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Posted 19 September 2015 - 06:58 AM

Hello JM:

 

I have called conical, but I think is not the right word, I do not know the name of this type of mirrors, ¿lightweight?.

It's the only thing my economy can afford:

 

http://www.teleskop-...est-Report.html

 

RF Royce seems that manufactures conical but I can not afford, or other options such as cellular mirrors.

 

Regards

Maximo



#14 Ian Robinson

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Posted 19 September 2015 - 10:12 AM

wow .... nice job



#15 Pinbout

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Posted 19 September 2015 - 10:16 AM

Hello JM:

 

I have called conical, but I think is not the right word, I do not know the name of this type of mirrors, ¿lightweight?.

It's the only thing my economy can afford:

 

http://www.teleskop-...est-Report.html

 

RF Royce seems that manufactures conical but I can not afford, or other options such as cellular mirrors.

 

Regards

Maximo

 

that looks the same as the skywatcher's 18 ul primary. they started protoyping with fused primaries but wound up with cast.

 

so tell me whats up with the tnuts on the end of the threaded stud on you steel balls. :grin:


Edited by Pinbout, 19 September 2015 - 10:17 AM.


#16 JM La Galette

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Posted 20 September 2015 - 11:56 AM

Thanks Maximo, looking forward to the next steps of your project,

JMarc


Edited by JM La Galette, 20 September 2015 - 11:57 AM.


#17 CanaryMax

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Posted 05 October 2015 - 07:13 AM

Hello:

Another little step, the spider and the secondary support. Need to give a good finish sanding and painting and place the connecting screws to the tube, I'm still doubting whether place two per leg or only one.
The legs are a laminate of three layers of fiber 240g / m2, thickness about 0.65mm, weighs 230g but still can be applied any weight reduction.

Regards

Maximo

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#18 JM La Galette

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Posted 05 October 2015 - 01:48 PM

Hello Maximo,

 

Nice job, however for the spider vanes I have personally chosen to stay on a "bright Stainless steel" for a thermal / heat radiation issue on my 16" Newt. Did you look at any potential users of such CF vanes and possible negative effects?

 

Thanks,

Jean-Marc



#19 CanaryMax

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Posted 05 October 2015 - 05:32 PM

Hello
I do not know if there are users interested...if i understand well your words.

Positive things are the small thickness of the legs, ease of construction,bug fixes, strudiness,and low cost.
If you dont have a workshop, tools, or you can not make noise because your neighbors complain, fiber is a solution
My 8" have a similar spider two years ago and i dont have any problem.

It is not the best solution if lightness is sought, there are lighter spiders, and low cost.
Regards
Maximo

#20 CanaryMax

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Posted 06 October 2015 - 08:26 AM

Hello

and the key to everything is here ...
Now I have to redesign the cell because it is useless what they had in mind for this mirror, is perhaps where most enjoy thinking about how to do it rather than do it.

Regards

Maximo

 

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#21 eyepiecedropper

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Posted 06 October 2015 - 01:39 PM

Hi Maximo, would you mind posting us Mr. Rohrs/ the TS mirror test report?

 

Thanks, Martin



#22 JM La Galette

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Posted 06 October 2015 - 03:38 PM

Thanks for your kind answer Maximo, however my question was more about the potential problem you would have with such CF vanes (thermal effects). If you did not notive any issue with the same vanes on your 8" then this is fine.

 

Thanks,

Jean-Marc



#23 CanaryMax

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Posted 06 October 2015 - 04:51 PM

Hello Jean Marc

I can not understand how it is possible that the spider legs cause problems of thermal effects. There should be a very large temperature difference and I see no reason for it.
I have experienced in a closed carbonfiber tube 14", strong internal currents while the primary cooling, when the mirror is balanced thermally everything is normal.

Martin, tomorrow i public the test now i cant.
Regards
Maximo

#24 JM La Galette

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Posted 07 October 2015 - 03:37 PM

Hello Maximo,

 

Actually I refer to material emissivity. Your black carbon vanes are close to a black body, emissivity near 1, whereas a polished stainless vane has an emissivity around 0,1. Theorically that would mean the CF one will emit more thermal radiation than the metal polished one, but to be fair first I haven't checked this myself, and second I don't know whether this means anything in our case. I can only say I have taken this into account for my own tube and went to Stainless steel vanes, where everything else is carbon ! :)

 

https://en.wikipedia...wiki/Emissivity

 

Would be happy to hear that no problem occur, then I'll change my vanes to carbon in the future too !

 

Thanks,

Jean-Marc


Edited by JM La Galette, 07 October 2015 - 03:38 PM.


#25 JM La Galette

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Posted 07 October 2015 - 04:13 PM

Just found this, this may be of interest to you.

 

http://www.cloudynig...

 

and this too.

http://www.cloudynig...er-vanes/page-8

 

Jean-Marc




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