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Bryan JR
member


Reged: 01/10/12

Which Sonotube best for Telescope tube? new
      #6429548 - 03/26/14 01:50 AM

I've wanted to mount my 12" mirror in a smaller diameter tube.
Just discovered my Menards sells over sized tube on order at reasonable prices.

http://www.menards.com/main/search.html?search=14"+x+12%27+Sonotube

Which one-commercial or standard-is best for a telescope tube? Or does anyone know the advantages vs. disadvantages for each? Anyone know wall thicknesses?

Thanks in advance


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Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Which Sonotube best for Telescope tube? new [Re: Bryan JR]
      #6429764 - 03/26/14 07:49 AM

which has a 3/8" wall thickness?

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roscoe
curmudgeon
*****

Reged: 02/04/09

Loc: NW Mass, inches from VT
Re: Which Sonotube best for Telescope tube? new [Re: Pinbout]
      #6429773 - 03/26/14 07:58 AM

The 'commercial' is the thicker stuff, as far as I know.

From what I have seen, all the big boxes sell the thinner version, which is ok for being buried, but I wouldn't go more than a foot or so unsupported with it. If needed, a 2x4 frame around one will keep it from tipping or warping, but by the time you put the time and money into supporting a cheap one, you might as well drive another 20 minutes and spend another $20....

Masonry supply houses and many 'local' lumber yards sell the better-grade stuff.

The clue here is to look in the parking lot....if there are more pickups than cars, that's where the pros shop, that's where the pro-grade supplies are.....
R


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Chuck Hards
Post Laureate
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Reged: 05/03/10

Loc: The Great Basin
Re: Which Sonotube best for Telescope tube? new [Re: roscoe]
      #6429792 - 03/26/14 08:14 AM

If you live in a metro area, there may be concrete supply stores that specialize in all things concrete, including tube forms. They will have the heavy-walled stuff, and often the prices are competitive with the big box home centers. You may even be able to get the type with an unwaxed interior, making flocking or blacking-out much easier.

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cheapersleeper
Post Laureate
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Reged: 01/22/10

Loc: Sachse TX
Re: Which Sonotube best for Telescope tube? new [Re: Chuck Hards]
      #6429846 - 03/26/14 09:04 AM

I live in an area of high pickup truck density, I went to a store that specializes in structural steel and concrete stuff, I had to buy 14' to get 14" and it is only a bit thicker than the big box stores. My experience is markedly different from what all of you are describing. Good glued end rings stiffen them up a lot and a couple of internal ones would really help.

B


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Alan French
Night Owl
*****

Reged: 01/28/05

Loc: Upstate NY
Re: Which Sonotube best for Telescope tube? new [Re: cheapersleeper]
      #6430025 - 03/26/14 10:54 AM

Either type, but especially the thin-walled version, greatly benefits from some good, stiff end rings. (On the back, the interior cell back can provide the stiffness.)

With the brand name "Sonotube," the interior wax layer is easy to strip out.

Leave the wax layer on the outside, and cover it with cloth. Easy and looks great.

Clear skies, Alan


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Chuck Hards
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Reged: 05/03/10

Loc: The Great Basin
Re: Which Sonotube best for Telescope tube? new [Re: Alan French]
      #6430040 - 03/26/14 11:03 AM

I have to admit that I now only use such tubes as disposable mandrels for laying-up fiberglass tubes. But they still have their use as an economic means to and end.

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MikeMcCaskey
professor emeritus


Reged: 03/09/12

Loc: South Central Kansas
Re: Which Sonotube best for Telescope tube? new [Re: Chuck Hards]
      #6430079 - 03/26/14 11:31 AM

I visited one of the concrete stores here in Wichita, they sell tubes in 16 foot hanks and wouldn't consider cutting one. They didn't have any scraps either. Something to consider, maybe the local astronomy club would go in on a long section.

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Chuck Hards
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Reged: 05/03/10

Loc: The Great Basin
Re: Which Sonotube best for Telescope tube? new [Re: MikeMcCaskey]
      #6430105 - 03/26/14 11:42 AM

My local concrete supply store has a nice saw especially for cutting these tubes, and happily cuts them to any length needed. The cut is remarkably square. You do have to buy the entire 14-foot length, however.

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Alan French
Night Owl
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Reged: 01/28/05

Loc: Upstate NY
Re: Which Sonotube best for Telescope tube? new [Re: MikeMcCaskey]
      #6430108 - 03/26/14 11:42 AM

I usually bought a 16 foot length, cut it so I could load it into the car, and either saved or sold the unused section. They're also great for making kitty condos, which I've done, and our house rabbits enjoyed them as "tunnels."

Clear skies, Alan


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Jeff Morgan
Postmaster
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Reged: 09/28/03

Loc: Prescott, AZ
Re: Which Sonotube best for Telescope tube? new [Re: Alan French]
      #6430165 - 03/26/14 12:23 PM

Quote:

With the brand name "Sonotube," the interior wax layer is easy to strip out.




How is this done?


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Alan French
Night Owl
*****

Reged: 01/28/05

Loc: Upstate NY
Re: Which Sonotube best for Telescope tube? new [Re: Jeff Morgan]
      #6430192 - 03/26/14 12:33 PM

I always just grabbed and pulled up an end and thin layer of tube and peeled. If the end I started with didn't work, I just started at the other end. Never had any trouble with getting it to work, although you need to take some care when you get far down the tube. Once you get past half way you can continue in the same direction, but from working at the other end of the tube.

Clear skies, Alan


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: Which Sonotube best for Telescope tube? new [Re: Alan French]
      #6430681 - 03/26/14 04:38 PM

i get my tubes from shapeunlimited.com

they have no wax...just have to stay with their stock sizes.

also...

http://www.aitwood.com/StoreFront.Asp?WoodType=PAPER&CATID=10&Section... Fiberboard Cylinders

they also carry real wood tubes, around $380 for a 14" dia.

Edited by Pinbout (03/26/14 04:44 PM)


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Bryan JR
member


Reged: 01/10/12

Re: Which Sonotube best for Telescope tube? [Re: Alan French]
      #6431484 - 03/26/14 11:55 PM

I'd prefer the thinner tube, and yes, I'm planning an internal ring primary mirror mount for one end and a strip glued inside at the focuser end.

My present tube is a 15" diameter 1/8" wall aluminum-I'm aiming for a smaller and lighter, possibly rotatable, OTA.

The heavier duty sonotube would be ok, if I knew it wouldn't cancel out weight savings or be appreciably harder to cut.

I'm in a rural area, so Menards is best, cheapest source for me. Thanks again for all the info.


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cheapersleeper
Post Laureate
*****

Reged: 01/22/10

Loc: Sachse TX
Re: Which Sonotube best for Telescope tube? new [Re: Bryan JR]
      #6431777 - 03/27/14 07:08 AM

Bryan JR, those tubes really need end rings. If you are a good craftsman you could make them really small out of plywood, but my 14" tube needed a glued ring on the sky end and was glued to a flange/plate thing on the other. Without those supports, those tubes are too flimsy.

B


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Chuck Hards
Post Laureate
*****

Reged: 05/03/10

Loc: The Great Basin
Re: Which Sonotube best for Telescope tube? new [Re: cheapersleeper]
      #6431837 - 03/27/14 08:17 AM

The biggest problem with unsupported cardboard tubes, from my experience, is sag at the spider attachment points. Any tension on the vanes at all, and the walls start to cave-in. Internal stiffening at that point is just as important as the tube ends.

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Dr. Woo
sage


Reged: 12/23/13

Loc: The IE
Re: Which Sonotube best for Telescope tube? new [Re: Chuck Hards]
      #6434745 - 03/28/14 04:36 PM

I sanded and wrapped a Home Depot thin wall tube with Carbon Fiber. It's way strong now and still very light at 10 lbs for a 12" tube for my 10" Starfinder

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cheapersleeper
Post Laureate
*****

Reged: 01/22/10

Loc: Sachse TX
Re: Which Sonotube best for Telescope tube? new [Re: Dr. Woo]
      #6435148 - 03/28/14 08:55 PM

We need pics and a description, Dr..

B


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Alan French
Night Owl
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Reged: 01/28/05

Loc: Upstate NY
Re: Which Sonotube best for Telescope tube? new [Re: cheapersleeper]
      #6435185 - 03/28/14 09:27 PM Attachment (15 downloads)

Here's the simple approach. A 14.5" f/6 in a 16" Sonotube. The wax was left on the outside and the tube was covered with cloth. It comes apart just above the cradle, with a kinematic arrangement of contact points and latches to hold it together. The shield slides off - although that needs some work.

Clear skies, Alan


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Pinbout
Postmaster
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Reged: 02/22/10

Loc: nj
Re: Which Sonotube best for Telescope tube? new [Re: Alan French]
      #6435202 - 03/28/14 09:42 PM

How long ago did you make that.

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