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Equipment Discussions >> Reflectors

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saemark30
Pooh-Bah


Reged: 02/21/12

High End Components
      #5772920 - 04/02/13 01:13 PM

I'm looking to rebuild a 10" Newtonian. What are the better makers of mirror cells and secondary supports?

Who sells tubes of 12" dia. or so?


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5773181 - 04/02/13 03:42 PM

a 10" cell is easy enough to make, or you could spend 300 for an aurora precision cell that you still have to glue to your mirror...

draw it up.



then cut it up.



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Pinbout
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5773224 - 04/02/13 04:02 PM

i forgot to say, i could have had the two plates and rocker bars waterjetted out of 1/4" alum for only $40 labor $20 material. I just wanted to make it out of wood this time for the halibut.

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saemark30
Pooh-Bah


Reged: 02/21/12

Re: High End Components new [Re: Pinbout]
      #5773296 - 04/02/13 04:41 PM

I bet it looks great in alum too. I could modify an existing cell with rocker bars.
What do you use for a secondary holder and spider Danny?


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davidpitre
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Reged: 05/10/05

Loc: Central Texas
Re: High End Components new [Re: saemark30]
      #5773362 - 04/02/13 05:03 PM

How thick is your mirror?
Here is a nice cell: http://www.aurorap.com/prod-AZ-mirror-cell.htm, though it requires silicone. Carl Zambuto says silicone works great on these smaller mirrors. I wouldn't be big on it, but I sure wouldn't argue with Carl. I believe Portaball silicones their mirrors in , and few have anything bad to say about that set-up.
JPAstrocraft will also make you a 6 point cell for your 10". He does wonderful work: http://www.jpastrocraft.com/cells.htm ...and you get edge support.
Some of the better secondary mirror supports come from Astrosystems and Protostar.
Protostar sells a nice non-metallic tube. Hastings is likely the least expensive place for aluminum tubes. There are now several places for carbon fiber 12" tubes if that is what you are after.


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saemark30
Pooh-Bah


Reged: 02/21/12

Re: High End Components new [Re: davidpitre]
      #5773609 - 04/02/13 06:13 PM

The mirror is around 1 3/8" thick.

Who makes carbon fiber tubes?
They are very expensive.
Would it be practical to make one?


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Pinbout
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5773614 - 04/02/13 06:17 PM

astrosystems for secondary spiders

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Pinbout
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5773633 - 04/02/13 06:27 PM

Optical Support - $229

but they're temporarily off line 6-12 months.


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: High End Components new [Re: Pinbout]
      #5773644 - 04/02/13 06:32 PM

Mirror Cells, cell parts, and knowledge about them:
http://web.telia.com/~u41105032/spider/spider2.htm
http://astrosurf.com/altaz/astatic.htm
http://aurorap.com/prod-mirror-cell.htm
http://www.bellevillesprings.com/belleville-washers.html
http://www.davidlewistoronto.com/plop/design.htm
http://www.dobstuff.com/mirrorcell.htm
http://www.cruxis.com/scope/mirroredgecalculator.htm
http://www.jpastrocraft.com/cells.htm
http://www.mcmaster.com/#belleville-disc-springs/=gmve8g
http://www.greenhulk.net/forums/showthread.php?t=104558&page=2
http://www.meridiantelescopes.com/primary.htm#primarymirrorcell
http://www.atmsite.org/contrib/Holm/Plop_optimized_cells/index.html
http://www.cruxis.com/scope/mirrorcooling.htm
http://www.oneilphoto.on.ca/news.htm
http://www.opticalsupports.com/
http://www.davidlewistoronto.com/plop/
http://astrosky.homestead.com/price.html
http://www.universityoptics.com/telescope-making-supplies.html

I do not recommend a full-tube scope, even if the scope will be housed permanently in an observatory. If Alt-Az, the center of gravity will be too high, a rigid-enough structure will weigh a huge amount in any size over 12", and mirror cell design will make insertion of the mirror and cell difficult because of weight. In a truss design, the structure can be very rigid yet significantly lighter. And, the scope will be easier to construct and transport.

This is less of a problem for a 10", but even then, finding a rigid non-steel tube of 12" I.D. will be difficult and expensive. You could almost make the entire housing for the price of a tube, if the tube is fiberglass or phenolic materials. Carbon fiber would be difficult to find, and an aluminum tube will be fairly heavy if you find one that big.

There are just so many advantages to the truss design, I can't recommend a tube for your scope. 8" and smaller, maybe. But the only reason to have a 10" tubed scope is because it came that way, IMO.

Edited by Starman1 (04/02/13 06:37 PM)


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rgconner
member


Reged: 03/17/13

Loc: Sacramento, CA
Re: High End Components new [Re: Starman1]
      #5773669 - 04/02/13 06:45 PM

Carbon tubes are easy to come by on the web...

but you are looking at around $1200 or more.


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5773918 - 04/02/13 08:16 PM

you can get a wood 12" tube

Aitwood Anerson for $127


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: Starman1]
      #5773926 - 04/02/13 08:18 PM

don astrosky and optical support are down not out but astrosky won't be back till 2015.

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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: Pinbout]
      #5773941 - 04/02/13 08:30 PM

shapes unlimited also sells cardboard tubes

you have to order their standard sizes

but I got a 10in x 96in which they cut in half for ~$70


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Daud
sage


Reged: 08/05/06

Loc: AZ, Scottsdale
Re: High End Components new [Re: Pinbout]
      #5774234 - 04/02/13 09:51 PM

What about cost and source for carbon fiber trusses ?

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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: High End Components new [Re: Daud]
      #5774328 - 04/02/13 10:32 PM

Quote:

What about cost and source for carbon fiber trusses ?



Saw one quote recently for about $180 per foot.


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herrointment
Post Laureate
*****

Reged: 03/12/11

Loc: North of Hwy. 64
Re: High End Components new [Re: Starman1]
      #5774451 - 04/02/13 11:38 PM

Danny...way cool links. Thanks!

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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: herrointment]
      #5774528 - 04/03/13 12:27 AM

both places will veneer the tubes for ya if ya don't won't to bother with that type of work.

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Chucky
sage
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Reged: 04/16/10

Loc: Dublin, Ohio
Re: High End Components new [Re: Pinbout]
      #5774764 - 04/03/13 06:57 AM

Anyone remember California Tubular Designs from ....oh say 10-12 years ago? Mark Wagner used to do some pretty cool custom tubes. I use one for my 10 inch F6. Is really nicely constructed with strong, good looking covering. Has strengthening end rings too.

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gaz-in
scholastic sledgehammer
*****

Reged: 12/17/07

Re: High End Components new [Re: davidpitre]
      #5774800 - 04/03/13 07:48 AM

Quote:

How thick is your mirror?
Here is a nice cell: http://www.aurorap.com/prod-AZ-mirror-cell.htm, though it requires silicone. Carl Zambuto says silicone works great on these smaller mirrors. I wouldn't be big on it, but I sure wouldn't argue with Carl. I believe Portaball silicones their mirrors in , and few have anything bad to say about that set-up.
JPAstrocraft will also make you a 6 point cell for your 10". He does wonderful work: http://www.jpastrocraft.com/cells.htm ...and you get edge support.
Some of the better secondary mirror supports come from Astrosystems and Protostar.
Protostar sells a nice non-metallic tube. Hastings is likely the least expensive place for aluminum tubes. There are now several places for carbon fiber 12" tubes if that is what you are after.




Chatting with Steve Swayze last weekend. He too speaks highly of siliconing mirror to cells.


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davidpitre
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Reged: 05/10/05

Loc: Central Texas
Re: High End Components new [Re: Pinbout]
      #5774840 - 04/03/13 08:20 AM

Quote:

Optical Support - $229

but they're temporarily off line 6-12 months.



I have a hard time with this cell for a standard (not conical) mirror. The 10" has 4 fixed points for bottom support. How is this a good idea?


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: davidpitre]
      #5775201 - 04/03/13 10:38 AM

Quote:

The 10" has 4 fixed points for bottom support. How is this a good idea?




it has 6 supports according to this drawing


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Jeff Morgan
Postmaster
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Reged: 09/28/03

Loc: Prescott, AZ
Re: High End Components new [Re: Daud]
      #5775227 - 04/03/13 10:55 AM

Quote:

What about cost and source for carbon fiber trusses ?




A google search will turn up many suppliers. I priced this out a couple of weeks ago. The bottom line is around 12x the cost of anodized aluminum.

On my scope it worked out to around $1500 to drop the center of gravity about 1-1/2".

Perhaps in a few more years additional production capability will come online to satisfy the demands of aerospace.


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: Jeff Morgan]
      #5775320 - 04/03/13 11:22 AM

dragon plate 1" x 72" braided cf tube $126

Moonlite 1" x72" anodized alum. $18

CF x7 more.


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davidpitre
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Reged: 05/10/05

Loc: Central Texas
Re: High End Components new [Re: Pinbout]
      #5775509 - 04/03/13 12:56 PM

Quote:

Quote:

The 10" has 4 fixed points for bottom support. How is this a good idea?




it has 6 supports according to this drawing



It looks like you are right, but that doesn't seem any better if they are all fixed. Certainly they don't provide equal or uniform support. For most 10" mirrors I'd rather 3 fixed points than 6.


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gaz-in
scholastic sledgehammer
*****

Reged: 12/17/07

Re: High End Components new [Re: davidpitre]
      #5775548 - 04/03/13 01:19 PM

at $45 this one looks interesting

19 MM OD by 48 inches CF Pole


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saemark30
Pooh-Bah


Reged: 02/21/12

Re: High End Components new [Re: gaz-in]
      #5776068 - 04/03/13 05:53 PM

Any source of tube clamps? I can't see anyone justifying paying $1200 for a CF tube.

What aren't there any pure dielectric coated diagonal mirrors for Newtonians? Coatings loose contrast even after cleaning.


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5776123 - 04/03/13 06:16 PM

Quote:

Any source of tube clamps?




I make them...

http://www.youtube.com/watch?v=sVpjifuRRXE

I have since turned them around and added thumb screws.


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careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: High End Components new [Re: saemark30]
      #5776148 - 04/03/13 06:33 PM

Quote:

...
Would it be practical to make one?




Yes and no.

It takes some experience working with CF and epoxy, it would be a poor choice for a first effort (rather like trying to make a large mirror by hand on your first go at mirror making).

If you want to try, my advice would be to use one of those HomeDepot Quiktubes as the inner part of tube (simplifying mold building and eliminating the problem of core mold removal) and trying it in fiberglass first as a practice run.

Carbon fiber fabric is not really terrifically expensive, Soller Composites has it at $2-$3 per square foot depending on weave and weight (fiberglass though runs only $0.50 to $0.75 per square foot).

Part of the reason for the high cost for carbon fiber tubes is that customers expect a perfect cosmetically unblemished bare carbon fiber surface for bragging rights. This means blemished tubes get scrapped, and you pay for them anyway when you buy the unblemished ones.

If you just want CF for its mechanical properties (light weight, stiffness, absence of thermal expansion) you can paint the end product (if blemished) and it will work the same. You can also get convincingly looking carbon fiber contact paper to cover your scope with to make it look like what it is, but in unblemished form.

Here are some good links showing techniques just posted on the ATM forum (Google Chrome automatically translates from Spanish):

http://canaryastro.webs.com/apps/photos/album?albumid=13105589
http://www.aagc.es/observatorio/modificacion-del-telescopio-orion-optics-14


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careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: High End Components new [Re: Jeff Morgan]
      #5776178 - 04/03/13 06:52 PM

As Jeff indicates it is hard to make a case for using carbon fiber truss tubes - is not a compelling application for the material.

Part of the reason* is that though CF is stiffer than aluminum, you can't make tubes any thinner for structural integrity reasons, so you only get the 40% weight savings from the lower density but at an enormous price increase.

You really need to be weight sensitive or have deep pockets to justify it.

The cost is not so much the cost of materials as the high cost of the cosmetic expectations of the buyers and consequently the production costs. It is a vicious circle.

If someone came out with a plain rough-looking CF product like so much fiberglass tubing costs could be much lower.

*Another part of the reason is that one of biggest advantages of using CF, or any composite fabric, is that you can use it with a low density core material to get an enormous increase in the stiffness to weight ratio. Tube walls are solid and so get no such benefit.

Edited by careysub (04/03/13 08:04 PM)


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5776494 - 04/03/13 09:10 PM

hey check out this old thread on making a CF tube.

if you can do a fiberglass tube you can do a CF tube.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3383451/page...


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careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: High End Components new [Re: gaz-in]
      #5776538 - 04/03/13 09:33 PM

Quote:

at $45 this one looks interesting

19 MM OD by 48 inches CF Pole




Ah! If you notice one of my earlier posts on this thread, I commented that the high cost of many carbon fiber components was mostly due to purely cosmetic considerations, and if the same techniques used in fiberglass tube production were used, you would get a rough looking product but it would be considerably cheaper.

That is exactly what this is - it is pultruded CF tubing, and if you zoom in on the image you see that it does not look so sleek with the polished fabric surface. But it saves you substantial $$.

This would be good tubing for a true truss system - the thick walls give a lot of resistance to elongation for the diameter.

Cost/performance for this is around two to four times what you would pay for aluminum tubing of similar performance and generally similar dimensions. But you could come close to cutting the weight in half.


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gaz-in
scholastic sledgehammer
*****

Reged: 12/17/07

Re: High End Components new [Re: careysub]
      #5777056 - 04/04/13 06:46 AM

Thes folks have a .75ID, .032WT by 70 incches for less than $50...

.75ID, .032 WT by 70 inch CF Tube for less than $50


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saemark30
Pooh-Bah


Reged: 02/21/12

Re: High End Components new [Re: gaz-in]
      #5777805 - 04/04/13 01:59 PM

Perhaps we can make a 12" tube from 12 sq ft of CF @3 x12 or $36 then add in cost of epoxy and put this over a cardboard tube and voila.

Is there something wrong with this idea?


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: High End Components new [Re: saemark30]
      #5777860 - 04/04/13 02:25 PM

no, I'm doin' that for a 6inf8. but the good expoy is $$

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mtb54703
professor emeritus
*****

Reged: 11/12/08

Loc: Eau Claire, WI
Re: High End Components new [Re: saemark30]
      #5777882 - 04/04/13 02:45 PM Attachment (17 downloads)

Quote:

Any source of tube clamps? I can't see anyone justifying paying $1200 for a CF tube.





Check out DJ lighting clamps - $5-$6 each - I've used 1.5" variety on my next scope project - same type of clamp that is used on Webster telescopes.


3/4"

1"

1.5" or 2"

Edited by mtb54703 (04/04/13 02:47 PM)


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mtb54703
professor emeritus
*****

Reged: 11/12/08

Loc: Eau Claire, WI
Re: High End Components new [Re: mtb54703]
      #5777886 - 04/04/13 02:50 PM Attachment (19 downloads)

Example...

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careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: High End Components new [Re: saemark30]
      #5777942 - 04/04/13 03:22 PM

Quote:

Perhaps we can make a 12" tube from 12 sq ft of CF @3 x12 or $36 then add in cost of epoxy and put this over a cardboard tube and voila.

Is there something wrong with this idea?




So the tube is 4 feet long, and 12" is diameter?

Actual costs might be $35 for a 36"x50"(standard width) piece of heavy weight (19.9 oz/square yard) of CF fabric, but you would need to undersize your tube slightly from 12" since 36"/Pi = 11.459" (unless they happen to cut you a little extra, typically they do but you can't count on it). This material is sold by the yard (some others are sold by the foot).

http://www.solarcomposites.com/composites/compositecarbon.html#12K

Sometimes they have remnant specials, check these out first:
http://www.sollercomposites.com/specialdeals.html

A good epoxy+hardener kit, enough for one layer of fabric, is available for $15.75 here:
http://www.uscomposites.com/epoxy.html


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davidpitre
Post Laureate
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Reged: 05/10/05

Loc: Central Texas
Re: High End Components new [Re: careysub]
      #5778024 - 04/04/13 04:07 PM

Mike.
Nice work there.


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JimMo
I'd Rather Do It Myself


Reged: 01/08/07

Loc: Under the SE Michigan lightdom...
Re: High End Components new [Re: mtb54703]
      #5780130 - 04/05/13 04:49 PM

Thanks for posting the link to the clamps. The 3/4" clamps are exactly what I've been looking for and cheap, too.

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JM La Galette
member


Reged: 11/24/07

Loc: France
Re: High End Components new [Re: JimMo]
      #5809990 - 04/20/13 02:48 AM

Quote:

Perhaps we can make a 12" tube from 12 sq ft of CF @3 x12 or $36 then add in cost of epoxy and put this over a cardboard tube and voila.

Is there something wrong with this idea?




Like this?



JMarc


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