Where To Get The Tube?

I will be making a 12.5", f/6-7 Newtonian starting soon. Until now, all
I have made (for myself) have been 10" or less, and aluminum tubing is
easily available from Hastings. BUT, Hastings' largest tubing is 12" OD,
and I will need 14" min. to 15" max. It will not be a Dob, and I want it
to be "closed-tube" for several reasons.

Does anyone know where to get 14"-15" tubing that is NOT SONOTUBE, and
not any other paper/cardboard composition?? I like aluminum, but
something in carbon-fiber or other material might be fine.

Thanks in advance;
Steve Sherrod

http://www.scopecity.com/tmc.htm

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To reply, remove the "z" if one appears in my address
"Stephen Sherrod" wrote in message
. com...
I will be making a 12.5", f/6-7 Newtonian starting soon. Until now, all
I have made (for myself) have been 10" or less, and aluminum tubing is
easily available from Hastings. BUT, Hastings' largest tubing is 12" OD,
and I will need 14" min. to 15" max. It will not be a Dob, and I want it
to be "closed-tube" for several reasons.

Does anyone know where to get 14"-15" tubing that is NOT SONOTUBE, and
not any other paper/cardboard composition?? I like aluminum, but
something in carbon-fiber or other material might be fine.

Thanks in advance;
Steve Sherrod

Besides rolling your own tube from aluminum, there is also Sonotube, more
properly concrete form tubes, that can be used.
In addition, you can also make up a tube from wood to whatever size you
need, either by gluing up a bunch of pieces and turning it to size or by
cuving plywood.

--
Bob May
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works evevery time it is tried!

Bob May wrote:
Besides rolling your own tube from aluminum, there is also Sonotube, more
properly concrete form tubes, that can be used.

Except of course that he specifically stated in his request that he did not
want Sonotube, or any other paper product.

Hey, it's his telescope, but a solid aluminum tube on a 12" sounds like a
disaster to me. There's a reason J.D. uses Sonotube.

Mojo
--
Morris Jones *
San Rafael, CA

http://www.whiteoaks.com

On Thu, 16 Oct 2003 22:06:28 +0000 (UTC), (Morris
Jones) wrote:


a solid aluminum tube on a 12" sounds like a disaster to me. There's a reason J.D. uses Sonotube.

Hi Mojo,

Just curious... why do you think aluminum wuold be a disaster, but Sonotube not?

Mark Wagner
Current projects (updated 10/3/03) http://www.astronomy-mall.com/projects.html

Hey, it's his telescope, but a solid aluminum tube on a 12" sounds like a
disaster to me. There's a reason J.D. uses Sonotube.

There are several reasons, it is cheap, available and it does the job. However
aluminum can also do the job and has the advantage of being potentially lighter
and stiffer.

Some day I will be upgrading my 12.5 inch scope to an aluminum tube, mostly to
reduce the weight. When I addressed this issue here before, I believe David
Knisely responded as well as several others who have large Newtonians with
aluminum tubes and they apparently work very well.

The sonotube is a substantial part of the scopes mass, I figured I could but my
OTA from 50 lbs down to about 35 lbs by going with an aluminum tube.

Someday.....

jon

Jon Issacs wrote:

Some day I will be upgrading my 12.5 inch scope to an aluminum tube, mostly to
reduce the weight. When I addressed this issue here before, I believe David
Knisely responded as well as several others who have large Newtonians with
aluminum tubes and they apparently work very well.

The sonotube is a substantial part of the scopes mass, I figured I could but my
OTA from 50 lbs down to about 35 lbs by going with an aluminum tube.

Well, aluminum tubes can work well *if* their interiors are properly insulated
with dark irregular flocking material. I used single layer cardboard
corrigation (sometimes found with packing material used in industry), as the
corrigations facing the interior of the tube can help break up tube currents
at the tube surface. I am replacing my 10 inch Newtonian's Sonotube with a
thick-wall Aluminum tube, and the weight is going to increase, so you won't be
saving a lot of weight unless you go with a really thin wall and do some
reinforcing, in which case, you would be better off going to a truss-tube.
Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
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I'm sorry, I thought I posted this a couple days ago, but it never
appeared.

Mark Wagner wrote:
Just curious... why do you think aluminum wuold be a disaster,
but Sonotube not?

I'm really not an expert at all, so I'm just talking for the sake
of talking, but three things come to mind with a large aluminum tube:
vibration, heat transmission, and expansion/contraction with temperature
changes.

I suppose there are ways to treat a large aluminum tube to deal with
all of these.

John Dobson is fond of saying, "They don't make bells out of cardboard."

It doesn't seem to me like an aluminum tube of equal stiffness to Sonotube
would be lighter. But again, I'm not speaking from experience.

Mojo
--
Morris Jones *
San Rafael, CA

http://www.whiteoaks.com

It doesn't seem to me like an aluminum tube of equal stiffness to Sonotube
would be lighter. But again, I'm not speaking from experience.


Given the constraints of the diameter of the tube, I think it is relatively
easy to design an aluminum tube that is both stiffer and lighter than a
Sonotube.

jon isaacs

Well folks, I've got a humoungous (technical term ..) 12" aluminum tube and
primitive pier mount laying on my garage floor. Got it for free, someone in
the astronomy club was going to toss it. It's free to someone who wants to
pick it up in Colorado Springs ..

"Morris Jones" wrote in message
...
Bob May wrote:
Besides rolling your own tube from aluminum, there is also Sonotube, more
properly concrete form tubes, that can be used.

Except of course that he specifically stated in his request that he did
not
want Sonotube, or any other paper product.

Hey, it's his telescope, but a solid aluminum tube on a 12" sounds like a
disaster to me. There's a reason J.D. uses Sonotube.

Mojo
--
Morris Jones *
San Rafael, CA

http://www.whiteoaks.com