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Equipment Discussions >> ATM, Optics and DIY Forum

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PhotoGazer
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Reged: 09/26/07

Round Wooden Tubes?
      #4220001 - 11/30/10 09:56 PM

Has anyone here made an OTA tube out of wood and made it round? If so, do you have any tips or ideas you want to hand down. I am thinking of doing this for my 5.5" OA Newt, and would appreciate any insight.

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rboe

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Reged: 03/16/02

Loc: Phx, AZ
Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4220038 - 11/30/10 10:15 PM

We had a tread on that started by cocobolo (sp?) around here somewhere. Might be in the Archive section. He was unable to finish due to health problems. But it's a great start.

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tim53
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Re: Round Wooden Tubes? new [Re: rboe]
      #4220108 - 11/30/10 11:01 PM

Ron:

I remember that thread, and wondering what happened to it. I'm sorry to hear he wasn't able to finish it.

I've been cogitating about how to go about this. It does seem as though the best way to get a round tube would be to start with a coopered tube and sand it round.

I've always made faceted tubes out of plywood so I wouldn't need to build a form before building the tube - I just tape up the slats on a flat surface, put glue in the joints, and roll it up to dry. This is fine if you don't need to rotate your tube. But if you do, fitting rotating rings to a polygonal tube is harder than it might sound (see my own recent experiences with this here .

Of course, if you don't need to rotate, polygonal tubes aren't a problem at all.

So, I'm thinking that I might try making a coopered tube for a small refractor project I have waiting around. The tube would be small enough that I could turn it on my Harbor Freight wood lathe (12x36).

I'd also be interested in hearing others' experiences making round wood tubes.

-Tim.


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plyscope
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Reged: 11/23/06

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Re: Round Wooden Tubes? new [Re: tim53]
      #4220158 - 11/30/10 11:30 PM

Check out this webpage by Dave Gault, an Aussie ATM.
wood tube reflector

Andy


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rboe

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Reged: 03/16/02

Loc: Phx, AZ
Re: Round Wooden Tubes? new [Re: plyscope]
      #4220577 - 12/01/10 08:47 AM

You could make a couple grooves that are round in the areas you want the rings in. But sanding it round after the fact would work too. Just a lot of work!

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rboe

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Reged: 03/16/02

Loc: Phx, AZ
Re: Round Wooden Tubes? new [Re: rboe]
      #4220580 - 12/01/10 08:49 AM

Pretty cool website there Andy.

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tim53
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Re: Round Wooden Tubes? new [Re: rboe]
      #4220647 - 12/01/10 09:42 AM

Quote:

You could make a couple grooves that are round in the areas you want the rings in. But sanding it round after the fact would work too. Just a lot of work!




I agree. Probably a better way would be to make a jig to support a router, and turn it round with a router instead of a sander.

I thought of using thin, bendable plywood, too. But the cost would have been 3 or 4 times that of a single sheet of 1/4" plywood.

-Tim.


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JohnH
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Re: Round Wooden Tubes? new [Re: tim53]
      #4220696 - 12/01/10 10:15 AM

I plan for a 10" f/6 to make a round wood tube out of maple staves.

I bought a router bit designed to cut a bird's mouth in one side and then you can glue it up from there.


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rboe

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Reged: 03/16/02

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Re: Round Wooden Tubes? new [Re: JohnH]
      #4220786 - 12/01/10 11:00 AM

John, keep us posted on the birds mouth bit project. I see those bits for sale and I'm always tempted but have not pulled the trigger.

Tim; jig and router sounds like the cat's meow.


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Achernar
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Loc: Mobile, Alabama, USA
Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4220822 - 12/01/10 11:13 AM

I made the shell in my 15-inch Dob's upper cage from 1-inch beveled wide slats of plywood. I used blue painter's tape to hold them together on the outside, then put glue in the gaps. Then I wrapped the assembly around a mandrel made of wooden disks of the desired inside diameter and used web clamps to hold the slats in place until the glue dried. All you need do is figure out the circumference of the tube on the outside, how many slats you will need and their width, then the angle of the bevel necessary. Use a table saw and push sticks to make the slats. Titebond or any other similiar yellow wood glue is an good choice for bonding the slats together. If you want to stain and varnish the tube, use a solid hardwood such as oak or cherry, and be careful to remove all traces of glue on the outside before staining. Always use an exterior grade polyurethane if you opt to varnish it, because other varnishes, shellacs and lacquers will rapidly degrade and fail.

Taras


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ed_turco
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Reged: 08/29/09

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Re: Round Wooden Tubes? new [Re: JohnH]
      #4220829 - 12/01/10 11:16 AM Attachment (81 downloads)

A wood lathe would be a great saver of time, if you know how to use one. I recall an article in the Gleanings section of S&T from the 1950's (Anyone got the DVDs?) where an ATM made his own approximation of a wood lathe with the centers staked into the ground, a motor attached to the ground and some ropes to pulley the polygonal thing along. I think he did a 7" tube (or so) about 5 ft long.

Please remember that I am drawing upon something I read in the early 1970's.

I did make a tube out of cherry in the early 90's out of a 16 sided polygon that I cobbled together.

I have a industrial wood lathe and used a rasp to get the roundness about right, and successive grades of files and then sandpapers to complete the job.

The cherry was 3/4" thick. The tube 7.5" in diameter and 20" long.

I disassembled and refigured a 6" f/6 portrait lens and made an RFT refractor out of it. Still works great.



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eric moerman
sage


Reged: 11/08/03

Loc: belgium
Re: Round Wooden Tubes? new [Re: ed_turco]
      #4220903 - 12/01/10 11:57 AM Attachment (110 downloads)

Hi,

i have made several wooden round tubes for newtons of 6" up to 16".
Here are a couple of picture of a 15" tube.
I use normal plywood for the rings and "airgraft plywood"(thats how they call it here) of 1mm thick.
For the piece that need to be stronger (mirror cell ,focuser) i use 2 layers of 1mm.
Very strong and lightweight.

eric


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eric moerman
sage


Reged: 11/08/03

Loc: belgium
Re: Round Wooden Tubes? new [Re: eric moerman]
      #4220905 - 12/01/10 11:58 AM Attachment (91 downloads)

2 picture

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tim53
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Round Wooden Tubes? new [Re: Achernar]
      #4220909 - 12/01/10 11:58 AM Attachment (65 downloads)

Quote:

I made the shell in my 15-inch Dob's upper cage from 1-inch beveled wide slats of plywood. I used blue painter's tape to hold them together on the outside, then put glue in the gaps. Then I wrapped the assembly around a mandrel made of wooden disks of the desired inside diameter and used web clamps to hold the slats in place until the glue dried. All you need do is figure out the circumference of the tube on the outside, how many slats you will need and their width, then the angle of the bevel necessary. Use a table saw and push sticks to make the slats. Titebond or any other similiar yellow wood glue is an good choice for bonding the slats together. If you want to stain and varnish the tube, use a solid hardwood such as oak or cherry, and be careful to remove all traces of glue on the outside before staining. Always use an exterior grade polyurethane if you opt to varnish it, because other varnishes, shellacs and lacquers will rapidly degrade and fail.

Taras




That's similar to what I did with my 10" f/6's tube, but I should have made mandrels to force it rounder than it is.

-Tim.


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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4220942 - 12/01/10 12:15 PM Attachment (84 downloads)

Here's one I made in a similar manner to the 10"er's tube, but using solid stock vermillion padauk, resawn on my bandsaw and thickness planed to 1/4" thick. This was to be for a 5" f/5 refractor, but I'm starting to think I should leave the lens in the PVC tube it came in (probably dates to the 50's or 60's).

-Tim.


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JohnH
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Re: Round Wooden Tubes? new [Re: rboe]
      #4220992 - 12/01/10 12:40 PM

Quote:

John, keep us posted on the birds mouth bit project. I see those bits for sale and I'm always tempted but have not pulled the trigger.

Tim; jig and router sounds like the cat's meow.




I got the wood two years back at a store. They were blowing it out because it had gotten water-damaged. It turned out to be spalted maple. The fungus creates interesting patterns in the wood.

Its all ripped and planed to the right thickness, I just have to get my ambition together to work in my cold shop for a few days.

The bit came from Lee Valley. They come in different types. Mine can do either 6 or 12 sides. To do 6 or 16 sided objects, you need separate bit for each.

You can also do conical forms using tapered staves.


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JohnH
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Re: Round Wooden Tubes? new [Re: tim53]
      #4220994 - 12/01/10 12:42 PM

Quote:

Here's one I made in a similar manner to the 10"er's tube, but using solid stock vermillion padauk, resawn on my bandsaw and thickness planed to 1/4" thick. This was to be for a 5" f/5 refractor, but I'm starting to think I should leave the lens in the PVC tube it came in (probably dates to the 50's or 60's).

-Tim.




Do you have photos inside the ends? I always like seeing how wooden constructs are put together inside.


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tim53
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Re: Round Wooden Tubes? new [Re: JohnH]
      #4221012 - 12/01/10 12:51 PM Attachment (89 downloads)

It's ridiculously simple. When I made the first tube like this, I was worried it wouldn't be strong enough, but glues these days!...

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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4221019 - 12/01/10 12:54 PM

...but I like the idea of the birdsmouth bits for a stronger joint. They'll also "control" the angle without needing a form.

One could make more or fewer-sided tubes by building a jig to feed the work into the router bit at an angle to the table. I've thought about doing something like this, since I like odd-numbered polygons.

-Tim.


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ZeroID
sage


Reged: 04/21/10

Loc: Auckland, New Zealand
Re: Round Wooden Tubes? new [Re: tim53]
      #4222064 - 12/01/10 08:03 PM

Have a look at this Japanese Astronomers site
http://www.geocities.jp/toshimi_taki/index.htm
Lots of other interesting stuff there as well


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JohnH
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Re: Round Wooden Tubes? new [Re: ZeroID]
      #4222111 - 12/01/10 08:25 PM

I forgot I did this experiment using some off-cuts of MDF in an octagonal fashion.

I did as tim5.3 did, just taped the outside faces, spread glue on the cuts between, pulled them together and let dry.

I was also very skeptical this would support any large amount of weight.

It dryed for a few weeks and then I pushed it down on the floor and finally STOOD on it without it breaking. I actually had to jump on it to get this short section ~16" or so to fracture. The glue failed.


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Astro88
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Reged: 08/30/09

Re: Round Wooden Tubes? new [Re: ZeroID]
      #4222245 - 12/01/10 09:25 PM

I know you asked for tips on making a wooden tube, not buying one, but there is a company called Anderson International Trading that sells them. For example:

http://www.aitwood.com/StoreFront.Asp?ItemID=37500&wdesc=Pedestals%2048%20inches%20Tall%20Paint%20Grade

Click on Millwork Components, then Plywood Cylinders to view all the sizes they make.


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Brian Reed

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Reged: 10/29/04

Loc: North East Illinois
Re: Round Wooden Tubes? new [Re: Astro88]
      #4222414 - 12/01/10 10:55 PM

Check out Chuck Fellows scopes. He has instructions on his web page

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tim53
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Re: Round Wooden Tubes? new [Re: Brian Reed]
      #4222456 - 12/01/10 11:30 PM

Lots of neat stuff there. I'd seen Chuck Fellow's site before, but not the Japanese guy's!

I made my Cass's tube similarly, a few sides at a time. But I had longitudinal ribs (corners, really) to define the angle between sides. I did it this way to avoid having tube currents cascading off baffles inside the tube and into the light path, which was a problem I had on a prior tube for those optics: Cass thread

-Tim.


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ColoHank
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Re: Round Wooden Tubes? new [Re: tim53]
      #4222486 - 12/01/10 11:59 PM Attachment (45 downloads)

I made a round tube for a Galileo scope built-up from sixteen staves of red alder. I too used blue masking tape to hold the staves together while I applied a liberal amount of plastic resin glue (that glue has a long open time, so it won't set prematurely). Then I rolled the assembly up, tightly wrapped the resulting tube with nylon monofilament fishing line to exert even pressure all around, rolled the whole assembly back and forth across a table until the staves squirmed into proper registration with one another, and then set it aside overnight to let the glue cure. Hand-sanding of the exterior removed the sixteen facets to produce a tube that was uniformly round from one end to the other.

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DarkSkys
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Reged: 10/11/10

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Re: Round Wooden Tubes? new [Re: ColoHank]
      #4222522 - 12/02/10 12:40 AM

Anyone know what the dementions of the boards would have to be for a 6 sided tube? I'm planning to make it out of poplar boards, useing a table saw to cut the angles, and then useing a biscut cutter and biscuts+ glue to make a tough,lightweight and good lookin tube.

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scopemankit
sage


Reged: 01/27/09

Loc: south africa
Re: Round Wooden Tubes? new [Re: ZeroID]
      #4222655 - 12/02/10 03:09 AM

I made a 127mm rich-field telescope in 1999. The tube was of strips of different color merante, wood 6mm thick and 20mm wide. I cut the strips with a small angle so the pieces would nest together. They were then glued with polyester resin inside a pair of aluminum bands (one is hidden by the base cover made of denim). They fit very tightly inside the bands and every fourth strip was pop riveted to the bands. No mounting, you simply sat down and clutch the telescope, partially suspended by the fabric strap, to your body and enjoy the skies! It is very strong and, I believe it now lives in Canada.

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scopemankit
sage


Reged: 01/27/09

Loc: south africa
Re: Round Wooden Tubes? new [Re: scopemankit]
      #4222658 - 12/02/10 03:17 AM Attachment (52 downloads)

A picture of the "Peanut" 127mm rft

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dan_h
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Reged: 12/10/07

Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4223175 - 12/02/10 11:20 AM Attachment (44 downloads)

I made a round tube from slats for a 100mm Refractor. Finished size about 106mm outside. The dew shield was larger, about 130mm outside.

I cut 18 slats on the table saw and they went together perfectly. A quick pass with a plane over the high spots on the finished tube allowed for an easy sanding job. I used 20 slates for the dew shield. I used an on-line circle calculator to help with the arithmetic.

http://www.1728.com/circsect.htm

When cutting the slats, the angle bewteen two adjacent pieces is shared so each piece gets 1/2 the needed angle. Cut the angles just a hair large to ensure any gap at the joined pieces in on the inside. (If you need a 5 degree cut, make it 5.05 rather than 4.95)

I got my inspirations from Chuck Fellows. He does beautiful work that I cannot begin to match. Check out his telescopes on his site.

http://cfellows.com/

good luck with your project,

dan


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PhotoGazer
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Re: Round Wooden Tubes? new [Re: dan_h]
      #4224712 - 12/02/10 11:44 PM

Thanks for some really good ideas and links. I have several thought and ideas that I have developed from reading the comments here, and viewing the links. I plan to test some of them tomorrow in the wood shop. Just in case you don't know, I build guitars, but many of the techniques used in forming guitar bodies cannot be easily transferred over to the larger areas on wood used in telescope tubes. However, I have a large selection of beautiful and exotic woods at my disposal. Many of them were purchased in lots that contained the wood I wanted, but are not suitable for guitar tone woods. They are, however, terrific choices for telescope tubes. Since I started this thread, I am now more excited than ever about where I can go with this project. I plan to photograph the processes that I develop so others can take advantage of them, if they work out. Feel free to keep this thread going with more ideas and links if you have any. I think a lot of ATM'ers can take advantage of this info.

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FlashJohnson
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Reged: 10/14/10

Loc: Southern tip of Lake Michigan
Re: Round Wooden Tubes? new [Re: DarkSkys]
      #4228586 - 12/04/10 06:30 PM

To create a six sided cylinder, divide 360 degrees (the quantity of degrees in a circle) by the quantity of boards (a.k.a. "staves") you will use...(360/6=60).

Next, divide THAT number (in this case 60 degrees) by "two" (60/2=30) since each of the six boards has two ends each that need beveled... requiring a thirty degree bevel on each of the two ends of the "staves".

Write back if you need any more info, as I just recently completed making a series of wooden cylinders and found much information on websites that cater to wooden drum makers, of all people (yes Lucy, Rickey WILL BE HOME after tonight's show at de club! )

And by the way, C. Fellows' website (mentioned elsewhere in this thread) instructions are so incredibly well done, they've given me MORE REASONS to build my next scope......

Sheeeshhh... does it EVER end??? ;-)


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FlashJohnson
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Reged: 10/14/10

Loc: Southern tip of Lake Michigan
Re: Round Wooden Tubes? new [Re: FlashJohnson]
      #4228592 - 12/04/10 06:33 PM

Ooooops... my reply may be redundant, now that I have read more of the thread ... hope I didn't confuse things..... as is my usual "M.O."!

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tim53
Postmaster
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Round Wooden Tubes? new [Re: FlashJohnson]
      #4230854 - 12/05/10 08:18 PM Attachment (43 downloads)

Here's one I tossed together for a short-focus 3" lens I have:

Dark Lauan Mahogany. 13 staves, just cause it worked out that way. I don't like working with such narrow and thick pieces on the table saw. Freaked me out somewhat. And I've got a couple wide joints that'll need filling, probably with epoxy.

Here it is on the lathe for turning the OD:

-tim.


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tim53
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Reged: 12/17/04

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Re: Round Wooden Tubes? new [Re: tim53]
      #4230859 - 12/05/10 08:20 PM Attachment (38 downloads)

And here it is now. I tured a step in the end for mounting a ring to adapt the focuser to. I'm planning on using an old Jaegers focuser, but I might spring for a Crawmach if the lens is a good one (haven't ever looked through it).

-Tim.


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tim53
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Reged: 12/17/04

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Re: Round Wooden Tubes? new [Re: tim53]
      #4230862 - 12/05/10 08:21 PM

I hate that my Mac's "Preview" software will rotate the image from the iPhone as I took it, but it won't save it that way. sorry if looking at those makes you feel like you're going to fall over!

-Tim.


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Dane Lance
journeyman


Reged: 12/04/10

Re: Round Wooden Tubes? new [Re: tim53]
      #4231012 - 12/05/10 09:42 PM

I can only think of one question here...why on earth would you want to make the tube for a telescope out of a material so susceptible to movement with changes in humidity?

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cloudmagnet
sage


Reged: 12/04/08

Loc: Georgetown, Texas
Re: Round Wooden Tubes? new [Re: Dane Lance]
      #4231095 - 12/05/10 10:31 PM

Here's a link to building round sailboat masts....just like telescope tubes, only loooonger!!!
http://www.duckworksmagazine.com/06/howto/birdsmouth/index.htm


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tim53
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Reged: 12/17/04

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Re: Round Wooden Tubes? new [Re: Dane Lance]
      #4231265 - 12/06/10 12:24 AM

Quote:

I can only think of one question here...why on earth would you want to make the tube for a telescope out of a material so susceptible to movement with changes in humidity?




The trick is to stabilize it so moisture doesn't affect it. Epoxy or polyurethane.

...and don't forget materials that are susceptible to movement with changes in temperature or flexure - like aluminum, graphite-epoxy, fiberglass... the list does indeed go on.

-Tim.


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plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: Round Wooden Tubes? new [Re: Dane Lance]
      #4231353 - 12/06/10 02:10 AM

If it's good enough for Mr Fraunhofer then why not use wood?
Dorpat Refractor
Tim is correct, it is not so much the material you need to worry about, more the design and application. Wood is fine if the right type is chosen and it is protected with paint, sealer or varnish of some sort. I must admit I am biased.

Andy


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Dane Lance
journeyman


Reged: 12/04/10

Re: Round Wooden Tubes? new [Re: plyscope]
      #4231513 - 12/06/10 06:42 AM

Sorry guys, I didn't mean that to come across as any kind of put down. I've been woodworking for over 20 years, but I'm a total newbie to telescopes and astronomy and you guys certainly know way, way more than I do when it comes to scopes.

I just know how much wood moves, and how unevenly, even when it is sealed. You can never completely seal wood, even with epoxies, etc.

However, since I have a desire to try to contribute, I will say, if you can get it in the lengths you need, mesquite wood moves very little in comparison to most woods. It's also beautiful and strong, albeit pricey. It is hard on cutters though as it is very salicious.

I turn it "green" on the lathe, and even very thin walled bowls or hollow vessels rarely warp or crack when drying.


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rboe

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Reged: 03/16/02

Loc: Phx, AZ
Re: Round Wooden Tubes? new [Re: Dane Lance]
      #4231591 - 12/06/10 08:47 AM

For our purposes, visual use for the most part, wood is just fine. Sure it will move but if you assemble the staves with some care the movement will be even so you won't have stress cracks and it won't affect focus as the movement is quite slow over time.

All in all it works rather well; just don't leave it out in the weather.

I agree, you can't really seal up wood against moisture but a good finish will keep gross changes in moisture abosorbtion from happening and that is all you really need.


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ColoHank
Carpal Tunnel
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Reged: 06/07/07

Loc: western Colorado
Re: Round Wooden Tubes? new [Re: Dane Lance]
      #4232068 - 12/06/10 01:30 PM Attachment (49 downloads)

Quote:

I can only think of one question here...why on earth would you want to make the tube for a telescope out of a material so susceptible to movement with changes in humidity?







Wood movements induced by changes in humidity are far more pronounced radially (from pith to cambium) and tangentially (across-the-grain) than they are longitudinally (along-the-grain). Thus, a scope tube made of properly cured, more stable woods like mahogany, walnut or cherry would likely exhibit only modest changes in length in response to seasonal or other variations in ambient humidity. Such change could be easily compensated for by the scope's focus mechanism. Composite construction, where the tube is built-up of numerous staves (carefully selected for grain attributes) rather than produced by simply boring a hole through a log, also promotes stability because, with careful grain selection, each stave's tendency to shrink, swell or warp is subordinate to the whole assembly, and undesirable movements cancel one another out. I've attached a picture of the wood-tubed Merz und Mahler scope, with Fraunhofer objective, which has been in regular service at the Cincinnati Observatory for almost 170 years. It's not only functional, but also a thing of beauty.

Edited by ColoHank (12/06/10 09:57 PM)


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tim53
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Re: Round Wooden Tubes? new [Re: ColoHank]
      #4232440 - 12/06/10 04:22 PM

That's the bottom line, as to the real reason why most of us who used wood do so.

It's downright purdy!

I wish I could afford the quantity of African Blackwood it would take to make my next OTA. I've made pens of that stuff, and it's got the most amazingly deep purple-black tight grain!

-Tim.


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rboe

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Re: Round Wooden Tubes? new [Re: tim53]
      #4232562 - 12/06/10 05:14 PM

http://www.woodworkerssource.com/blackwood_african.html

Hard to shop on line due to defects, should really shop in person but the price runs about $80-$85 per board foot.

For folks that may not know, a board foot is 1" thick by 12" by 12".

Sounds pricey (it is) but when you do small projects you won't need that much and can splurge a bit. You probably would not want to floor your house in it - but a small refractor might be just the ticket.

I'd have more concerns about machining it.


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Re: Round Wooden Tubes? new [Re: tim53]
      #4233040 - 12/06/10 08:56 PM

Wow, That scope at the Cincinatti Observatory is beautiful. I feel that wood is a good choice for an optical tube. Sure it swells and moves a little, but very little. Would it be the best choice to a scope that is doing imaging constantly? Probably not. But most of us are talking visual use here, and as everyone knows, we are ALWAYS! fiddling with the focuser. Inaccuracies would be nearly non-existent. Attention to grain and runout would be a good idea for assembling the most stable tube, but not extremely critical. I think well made wood OTA's are functional as well as beautiful. Just look at Normand Fullums' work to see what wood can do with a scope.

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Re: Round Wooden Tubes? new [Re: rboe]
      #4233061 - 12/06/10 09:02 PM

Quote:

http://www.woodworkerssource.com/blackwood_african.html

Hard to shop on line due to defects, should really shop in person but the price runs about $80-$85 per board foot.

For folks that may not know, a board foot is 1" thick by 12" by 12".

Sounds pricey (it is) but when you do small projects you won't need that much and can splurge a bit. You probably would not want to floor your house in it - but a small refractor might be just the ticket.

I'd have more concerns about machining it.




Yeah, but African Blackwood is a rare exotic, and difficult to find in decent lengths and widths. Besides that, at $85 a board foot, you can get carbon fiber tubes, and maybe even honeycomb carbon fiber. If I had a choice of African Blackwood for a scope, or Carbon Fiber for the same price or less, I am going with the Carbon Fiber.


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tim53
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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4233255 - 12/06/10 10:43 PM

Quote:

Wow, That scope at the Cincinatti Observatory is beautiful. I feel that wood is a good choice for an optical tube. Sure it swells and moves a little, but very little. Would it be the best choice to a scope that is doing imaging constantly? Probably not. But most of us are talking visual use here, and as everyone knows, we are ALWAYS! fiddling with the focuser. Inaccuracies would be nearly non-existent. Attention to grain and runout would be a good idea for assembling the most stable tube, but not extremely critical. I think well made wood OTA's are functional as well as beautiful. Just look at Normand Fullums' work to see what wood can do with a scope.




I image with my wood scopes all the time!

-Tim


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rboe

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Re: Round Wooden Tubes? new [Re: tim53]
      #4233809 - 12/07/10 09:58 AM

When it comes to material choices logic may or may not enter into it. Sometimes we say we're gonna use X, price and logic be damned. You and I would choose something else (and I'm pretty sure they would not be the same thing).

Tim; did you post pics of your completed wood scopes yet? Could you pop in one or two here?


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Re: Round Wooden Tubes? new [Re: rboe]
      #4253271 - 12/16/10 09:05 PM

I hope to put up some pics soon of the wood round tubes that I am making and the system I am using to make them. Hopefully, they will possibly jog some new ideas. Anyone else doing anything along this line right now. BTW, I am ramping back the time in the shop until after the holidays.

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Re: Round Wooden Tubes? new [Re: cloudmagnet]
      #4253364 - 12/16/10 09:44 PM

Never thought about that type of joint. Thanks for sharing.

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Re: Round Wooden Tubes? new [Re: Pinbout]
      #4253536 - 12/16/10 11:15 PM Attachment (56 downloads)

Ron:

Here's one of my 10" f/6, in a 9-sided chinese mahogany 1/4" plywood tube (edit, this pic is more recent, and shows the current backplate/cell):

Edited by tim53 (12/16/10 11:28 PM)


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Re: Round Wooden Tubes? new [Re: tim53]
      #4253554 - 12/16/10 11:21 PM Attachment (45 downloads)

Here's my 12.5" f/23 Cass (Mirrors by Ed Beck) in a 1/4" Teak plywood tube with poplar corners and 3/4" Birch plywood backplate (rest of cell is Novak):

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Re: Round Wooden Tubes? new [Re: tim53]
      #4253576 - 12/16/10 11:37 PM Attachment (61 downloads)

Here's me and my 6" f/15 Jaegers in walnut plywood tube, at Mt Pinos classics star party in August 2009. The blue thing piggyback is a 6" f/5 Jaegers in a blue anodized aluminum tube.

The tube for the f/15 worried me a bit, because the plywood has an MDF core. But it's doing okay!


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Re: Round Wooden Tubes? new [Re: tim53]
      #4253762 - 12/17/10 02:08 AM

You do good work Tim. The wood tubes look great on the Tak green mounts.

Andy


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rboe

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Re: Round Wooden Tubes? new [Re: plyscope]
      #4253995 - 12/17/10 08:57 AM

Holy Moly Tim! Some very nice work there.

Have you considered making a wood version of the telerad - then gutting the plastic one for its' parts?


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Re: Round Wooden Tubes? new [Re: rboe]
      #4254054 - 12/17/10 09:40 AM

Wood is good. Thanks to all for posting some incredible pictures of their wooden scopes.

Regards,

Neil.


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Re: Round Wooden Tubes? new [Re: rboe]
      #4254965 - 12/17/10 05:59 PM

Quote:

Holy Moly Tim! Some very nice work there.

Have you considered making a wood version of the telerad - then gutting the plastic one for its' parts?




Funny you should ask! I haven't done this, but I've been thinking about making veneer inserts for the sides where they're recessed inside that ridge edge?

-Tim.


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Re: Round Wooden Tubes? new [Re: tim53]
      #4254982 - 12/17/10 06:06 PM Attachment (57 downloads)

Here's my 8" f/6 Springfield Newtonian, built in 1981. For this one, I used a sheet of 1/4" Indian Rosewood plywood. I remember thinking it was awfully expensive, at $48 for a 4x8 sheet. I doubt you can buy it anymore, and if you could, it'd be a heckuva lot more expensive!

-Tim.


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Re: Round Wooden Tubes? new [Re: rboe]
      #4255132 - 12/17/10 07:29 PM Attachment (53 downloads)

Quote:

Holy Moly Tim! Some very nice work there.

Have you considered making a wood version of the telerad - then gutting the plastic one for its' parts?




Here is a wooden "Telrad" on top of a "Schmidt and Wesson Cassegrain". I built this as a prop for an astronomy skit about 15 years ago. The Telrad is full size you can sorta get the idea of the size of the "scope". Nothing is functional.

BTW, beautful scopes, Tim!


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Re: Round Wooden Tubes? new [Re: StarStuff1]
      #4255363 - 12/17/10 10:00 PM

I think all of those scopes are beautiful. I hope my work stands up to those nice pieces. I was wondering about the rings I would use, but I noticed Tim made some beefy looking custom rings on the scope, with some Losmandy "D" mounting plates. That answers some of my questions. Tim, are those rings from plywood or solid wood?

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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4255378 - 12/17/10 10:12 PM

Mike:

They're 17" aluminum lazy susan bearings that I bought at Rockler. Cost ~$60 each, but that's cheap compared to Parks or Parallax rings for a 10" (really, probably a 12 or 14, since my tube isn't round). This thread has all the details!

-Tim.


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Re: Round Wooden Tubes? new [Re: tim53]
      #4259363 - 12/19/10 09:12 PM Attachment (54 downloads)

An update on that small wooden tube I was working on a couple weeks ago...

I turned a couple end rings for it - one to hold the lens and cell of a 3" f/6 achromat, the source of which I don't know - the other end to support a Jaegers 1 1/4" focuser I had laying around.

Here are the parts, laid out:


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Re: Round Wooden Tubes? new [Re: tim53]
      #4259367 - 12/19/10 09:13 PM Attachment (47 downloads)

And here are a couple of it drylabbed together.

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Re: Round Wooden Tubes? new [Re: tim53]
      #4259369 - 12/19/10 09:14 PM Attachment (35 downloads)

2

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Re: Round Wooden Tubes? new [Re: tim53]
      #4259374 - 12/19/10 09:17 PM

I have a couple things to do still...

The tube is about an inch too long to reach focus with the star diagonal, so I'll have to cut it shorter. The aluminum rings will be painted and the tube will be poly'd, maybe stained first.

I bought some "old brass" paint for the rings, but I wonder if that might be too much with the wrinkle black cell? Got a couple colors of hammertone paint - bronzish I think, that might work okay.

Will have to cogitate.

-Tim.


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slobeek
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Re: Round Wooden Tubes? new [Re: tim53]
      #4259805 - 12/20/10 03:36 AM

Guys help me out a little. If I want to make wooden tube (coopered) out of plywood...what is the minimum thickness of plywood for 8" tube?

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Re: Round Wooden Tubes? new [Re: slobeek]
      #4260199 - 12/20/10 10:58 AM

I've made all my plywood tubes out of 1/4". You might want to reinforce it, particularly if you have a large number of sides.

-Tim.


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slobeek
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Re: Round Wooden Tubes? new [Re: tim53]
      #4260250 - 12/20/10 11:20 AM

Thanks Tim. 1/4" it is then

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Re: Round Wooden Tubes? new [Re: slobeek]
      #4261618 - 12/21/10 01:28 AM Attachment (56 downloads)

If you use the best quality marine ply you can go thinner, I used 4mm occoume marine ply for my octagonal tubes. They are built with ply ring frame/baffles. It is light and strong. My next project wil be a octagonal tube for a 5 inch refractor using 3mm marine ply. This picture shows an octagonal tube made 4 years ago for a 6 inch refractor with 4mm ply sides and baffles. 12mm ply is used at the ends. This scope is similar to Tims nonagonal 6 inch f15.

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Re: Round Wooden Tubes? new [Re: plyscope]
      #4261670 - 12/21/10 02:18 AM

Very cool Andy. Does anyone have a program or equation that helps determine the size of the sections for the tube? In other words, if I wanted to have an 8" tube, and I wanted to use 8 slats for the tube, how wide would those slats have to be to make the 8" tube?

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Re: Round Wooden Tubes? new [Re: tim53]
      #4261755 - 12/21/10 03:30 AM

Quote:

Quote:

Holy Moly Tim! Some very nice work there.

Have you considered making a wood version of the telerad - then gutting the plastic one for its' parts?




Funny you should ask! I haven't done this, but I've been thinking about making veneer inserts for the sides where they're recessed inside that ridge edge?

-Tim.




Hmmmm. if i get a telrad, I might have to do that, to go along with the rest of the wood of my scope.


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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4262003 - 12/21/10 08:34 AM

Quote:

Thanks for some really good ideas and links. I have several thought and ideas that I have developed from reading the comments here, and viewing the links. I plan to test some of them tomorrow in the wood shop. Just in case you don't know, I build guitars, but many of the techniques used in forming guitar bodies cannot be easily transferred over to the larger areas on wood used in telescope tubes. However, I have a large selection of beautiful and exotic woods at my disposal. Many of them were purchased in lots that contained the wood I wanted, but are not suitable for guitar tone woods. They are, however, terrific choices for telescope tubes. Since I started this thread, I am now more excited than ever about where I can go with this project. I plan to photograph the processes that I develop so others can take advantage of them, if they work out. Feel free to keep this thread going with more ideas and links if you have any. I think a lot of ATM'ers can take advantage of this info.



I would just advise choosing the *lightest* wood possible.
I built a nice 8" square tube newtonian and the major drawback was how heavy it was ;-)
Jim


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DL Sharp
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Re: Round Wooden Tubes? new [Re: ColoHank]
      #4280436 - 12/30/10 03:10 PM

Quote:

I've attached a picture of the wood-tubed Merz und Mahler scope, with Fraunhofer objective, which has been in regular service at the Cincinnati Observatory for almost 170 years. It's not only functional, but also a thing of beauty.




I agree - The 1843 Merz und Mahler 11" Refractor at the Cincinnati Observatory is a thing of beauty. I've had the opportunity to look through it on many occasions. They have a photo gallery of it on the observatory's website:

http://www.cincinnatiobservatory.org/merzundmahlerref.html

While you're there, you might as well check out the photo gallery for their "New" scope, a 1904 Alvan Clark & Sons 16" Refractor:

http://www.cincinnatiobservatory.org/alvanclarksonsre.html


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dan_h
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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4280561 - 12/30/10 04:26 PM

Quote:

Very cool Andy. Does anyone have a program or equation that helps determine the size of the sections for the tube? In other words, if I wanted to have an 8" tube, and I wanted to use 8 slats for the tube, how wide would those slats have to be to make the 8" tube?




I use an on line circle calculator. It's amazing just how accurate this thing is. Certainly more accurate than I can cut wood.

http://www.1728.com/circsect.htm

Hope this helps,

dan


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Re: Round Wooden Tubes? new [Re: DL Sharp]
      #4280705 - 12/30/10 05:35 PM Attachment (34 downloads)

Quote:

I agree - The 1843 Merz und Mahler 11" Refractor at the Cincinnati Observatory is a thing of beauty. I've had the opportunity to look through it on many occasions.




I grew up in Mt. Lookout about 3/4 mile from the Observatory, a familiar neighborhood landmark. I first peeked through the Merz und Mahler when I was only about five or six years old. My parents were acting as chaperones one evening for a Girl Scout outing at the Observatory, and since I was too young to stay at home alone, I was dragged along. I have no recollection of what I viewed that night, but remember ascending a ladder or stairs of some kind to reach the eyepiece.

One evening in the autumn of 2008, after a lapse of sixty-one years, I was given the honor of removing the Merz und Mahler's lens cover (picture), after which I enjoyed my second peek through that scope -- this time at Jupiter.

My older sister was a classmate and friend of Marilyn Herget, whose father Paul was the Observatory's Director during my youth and beyond. Years later, while attending the University of Cincinnati, I was privileged to hear Dr. Herget speak at one of our regular geology department seminars about plotting minor planet and artificial satellite orbits and of his early adventures with the ENIAC computer.


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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4282453 - 12/31/10 12:29 PM

Yep - twin-skinned diaphragm construction is exceptionally rigid but lightweight for 17.5" Newt then Dob



ps: some hereabouts confuse round wooden tubes with multi-faceted tubes


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Re: Round Wooden Tubes? new [Re: nytecam]
      #4282499 - 12/31/10 12:49 PM Attachment (36 downloads)

LOL!

Well, *I* know the difference! Here's a few progress photos of my 3" f/6 Jaegers' tube. Here, I'm boring it out so it'll be round on the inside as well as the outside. Also, I needed to bore out the objective end quite a bit because it was so thick it was stopping down the lens to about 2 1/4"!

-Tim.


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Re: Round Wooden Tubes? new [Re: tim53]
      #4282507 - 12/31/10 12:52 PM Attachment (31 downloads)

Here, I've mounted it in my wood lathe so I could turn it by hand easier and work on the sanding and finishing of the exterior:

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Re: Round Wooden Tubes? new [Re: tim53]
      #4282514 - 12/31/10 12:54 PM Attachment (32 downloads)

And here it is with a second coat of poly/stain combo, waiting to dry:

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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4282522 - 12/31/10 12:59 PM

Still, it's taken me a LOT longer to make this round tube than it would to make a faceted tube. Part of that is because it's the first one I've tried, but most of it is in the turning from the glued-up staved tube. I may have been overly cautious in my cuts on the lathe, but I did have it bit and come out of the chuck a couple times, so it probably was a good idea to take it slow and easy.

It's also a very short tube. I'd like to make a matching tube for a 3" f/15 I have, but my lathe bed isn't long enough! (and I can't imagine boring something that deep - how would you support the tailstock end? Steady rest, I suppose. But my lathe doesn't have one).

-Tim.


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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4283143 - 12/31/10 05:37 PM Attachment (51 downloads)

Done except for buying brass fasteners to hold the lens cell and focuser. The ones sticking out of the lens cell end are temporary.

Next, I'll have to figure out how to mount it!

-Tim.

Edited by tim53 (12/31/10 05:38 PM)


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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4283148 - 12/31/10 05:39 PM Attachment (41 downloads)

too

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dan_h
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Re: Round Wooden Tubes? new [Re: tim53]
      #4283247 - 12/31/10 06:25 PM

Really nice. I like the color combo!

dan


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rboe

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Re: Round Wooden Tubes? new [Re: dan_h]
      #4284481 - 01/01/11 11:06 AM

Say Tim, how about some brass focuser knobs?

It looks so good I"m thinking of going the wood tube route instead of the kit that seems to be on long term hold. As fast as I work the kit may be available first.


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tim53
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Re: Round Wooden Tubes? new [Re: rboe]
      #4284528 - 01/01/11 11:23 AM

Ron:

I've thought about giving it a test drive and maybe adding a Crawmach if it's really good. So far, daytime views have been very nice, but I'm hand-holding it until I can make some rings that won't hurt the finish!

But that's just Rustoleum "old brass" paint over aluminum. Last time I bought a 1 5/8" x 12" bar of brass, it cost me $37. But I sure like turning brass on the lathe!

-Tim.


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PhotoGazer
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Re: Round Wooden Tubes? new [Re: tim53]
      #4288440 - 01/03/11 09:18 AM

Thanks for those snarking this thread about round wooden tubes. Yes, I am quite aware that they are not "truly" round. I have NEVER heard them called "faceted". But what we are talking about is closer to round than they are to square, and everyone else seemed to know what we were talking about as well. On to more questions. Thanks for the posting of that circle calculator link, but I find it very difficult to use. Does anyone know the formulas that would allow me to insert into an excel spreadsheet that would allow someone to put in values such as "Inside Diameter", "Number of Strips", "Strip Thickness", and get the spreadsheet to do the calculations to let me know how wide to make the strips, and the angle of the cuts to produce the tube tube with the ID desired?

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rboe

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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4288471 - 01/03/11 09:42 AM

Google search is dicey. You want to make staves and typically you want to know the number of strips/staves from the get go.

There are predetermined angles for known stave counts and folks even make router bits for that angle. But they don't tell you the width you need for a given diameter.


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Pinbout
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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4288620 - 01/03/11 10:59 AM Attachment (40 downloads)

Here's from Machinery's Handbook:

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Biff
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Re: Round Wooden Tubes? new [Re: rboe]
      #4288672 - 01/03/11 11:19 AM

Quote:

... and folks even make router bits for that angle.



Didn't even think of that. Sound like it would eliminate a lot of error rather than trying to dial in the TS blade to a good amount of accuracy.


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Pinbout
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Re: Round Wooden Tubes? new [Re: Biff]
      #4288744 - 01/03/11 11:49 AM

I always use a bevel protractor to set the angle of the blade, especailly when making compound angle cuts. Makes all the difference.

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nytecam
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Re: Round Wooden Tubes? new [Re: Pinbout]
      #4290546 - 01/04/11 04:38 AM

Quote:

I always use a bevel protractor to set the angle of the blade, especailly when making compound angle cuts. Makes all the difference.


Can a single bevel cut suit two adjoining sections if one piece is reversed

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Pinbout
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Re: Round Wooden Tubes? new [Re: nytecam]
      #4290753 - 01/04/11 08:48 AM

yes, it's a theorem in geometry

Parallels:

Alternate Interior Angles - If two parallel lines are cut by a transversal, then the alternate interior angles are congruent

Alternate Exterior Angles - If two parallel lines are cut by a transversal, then the alternate exterior angles are congruent.


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Attaboy
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Re: Round Wooden Tubes? new [Re: Pinbout]
      #4296312 - 01/06/11 03:04 PM

As a cheap alternative, you can use your miter saw, if you have one, to cross cut a 3" wide board and use that to set your tablesaw blade. You can usually get within half a degree with your miter saw... Chuck

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Chriske
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Re: Round Wooden Tubes? new [Re: tim53]
      #4296449 - 01/06/11 03:52 PM

Hi guys,

Another possible and simple way making 'wooden' tubes is using hardboard. Making hardboard wet one can bend it anyway you like. We use to make scopes out of this material.
You need water ....lots of it...!
It'll take you about 20 minutes to make a round tube out of a sheet of hardboard. Two of these tubes glued in one another makes a VERY strong, yet very light tube. You could stand on such, it won't deform at all. Not as light as carbon I know, but much cheaper. A 12" hardboard tube, 8 feet long will cost you about 7$ , glue included.
Some pictures...
(If I'm not mistaken I've posted this a few years ago... )







This is a smaller one 10" diameter almost 6 feet long.



We had lost of fun making these. Especially during hot weather...
These days we make trusscopes during course.


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dan_h
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Re: Round Wooden Tubes? new [Re: Chriske]
      #4296471 - 01/06/11 04:03 PM

Amazing! Thanks for posting.

dan


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Bob Myler
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Re: Round Wooden Tubes? new [Re: dan_h]
      #4296918 - 01/06/11 07:11 PM

Chris, could you share some more details on on how to bend/glue/seam hardboard - perhaps under a separate thread?

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rboe

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Re: Round Wooden Tubes? new [Re: Bob Myler]
      #4297373 - 01/06/11 10:46 PM

Chuck! I had hoped to go see you in Cave Creek some day - but you moved! Good to see you posting again. (PM me if need access to your old account).

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1E1HFPPE
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Re: Round Wooden Tubes? new [Re: PhotoGazer]
      #4333828 - 01/23/11 09:24 AM

Here is an article with great online calculators and an extensive set of equations.

Duckworks
http://www.duckworksmagazine.com/04/s/articles/birdsmouth/index.cfm#online-calc


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JohnH
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Re: Round Wooden Tubes? new [Re: 1E1HFPPE]
      #4334590 - 01/23/11 02:48 PM

Lee Valley's Bird's Mouth Bits come with this http://www.leevalley.com/en/shopping/Instructions.aspx?p=45202

I have helped build a spar for a boat (2 3/4" X 7" Sitka Spruce staves, seven sided form, some very small taper amounting to less than a half degree)

Edited by JohnH (01/23/11 03:44 PM)


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tim53
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Re: Round Wooden Tubes? new [Re: JohnH]
      #4334606 - 01/23/11 02:55 PM

Ooo!

I really want to try that for a tapered tube for a 3" f/15 lens I have waiting for a home!

-Tim.


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tim53
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Re: Round Wooden Tubes? new [Re: tim53]
      #4334619 - 01/23/11 03:00 PM

Chris:

How thick a sheet of hardboard did you use to bend?

-Tim.


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Jim Curry
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Re: Round Wooden Tubes? new [Re: Chriske]
      #4335166 - 01/23/11 06:48 PM

Chris:
This hardboard tube construction is intriguing, can we get you to start a thread with description and maybe photos?

Jim


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Jaimo!
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Re: Round Wooden Tubes? new [Re: Jim Curry]
      #4335467 - 01/23/11 08:51 PM

I don't normally read the ATM forum, but this subject caught my attention.

Here's a tube I coopered for a Zeiss 50/540 lens. I made this scope years ago, if I remember correctly I used 22 strips of red oak...

I have flocked the inside since the photo was taken.





Edited by Jaimo! (01/23/11 09:01 PM)


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imjeffp
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Re: Round Wooden Tubes? new [Re: Jaimo!]
      #4336946 - 01/24/11 03:02 PM

I don't know the details, but the 12.5" Harlan Smith Telescope at the Austin Astronomical Society's Eagle Eye Observatory is a wooden-tube newt on a custom GEM: http://www.austinastro.org/Default.aspx?pageId=755670

Quote:

We cut the strips of cedar on my table saw and glued them to each other while mounted on a cylindrical form per the description in the 50th Anniversary issue of S&T (September, 1992). We let the tube dry for about a year in his garage while researching ideas on how best to finish the tube. Tom found someone to help him apply fiberglass inside and out to make it much stronger and resistant to moisture. After that, I lost track of how the tube was finally put into use. But now everyone knows where and how the tube came into being.




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Thomas Karpf
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Re: Round Wooden Tubes? new [Re: Chriske]
      #4337005 - 01/24/11 03:34 PM

Chriske:

What are you using for an inner form for your hardboard tubes?


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Tim A.
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Re: Round Wooden Tubes? new [Re: Thomas Karpf]
      #4337550 - 01/24/11 07:03 PM

There is one word I expected to find in this thread, and did not:

Steampunk!

My dream is making an 6" f/6 Steampunk APO. Summayoo guys are way out ahead.


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tim53
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Re: Round Wooden Tubes? new [Re: Tim A.]
      #4337627 - 01/24/11 07:25 PM

Tim:

Take a look at one of Ross Sackett's Dobs. I think it's even been called "steampunk" somewhere.

I love the stuff. Wish I had the artistic bent.

...Hm... it just occurred to me that I know a graphic artist who might be able to help me come up with something!

-Tim.


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Tim A.
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Re: Round Wooden Tubes? new [Re: tim53]
      #4340643 - 01/26/11 12:11 AM

Quote:

... it just occurred to me that I know a graphic artist who might be able to help me come up with something![



Yeah. That'd be me, if we lived in the same place.

The telescope of my dreams is of brass and leather and wood and engraved cog-wheels. No stainless, no anodized aluminum, no paint, no plastic (as if!). It has understated ornamentation that befits the dignity of a scientific instrument, nothing over the top (as so much of Steampunk is). It pays homage to a bygone era, but with top-flight glass and optical design that could not have even been dreamed of back in the day. In the dark it plays with the best; in daylight, no one doubts they are in the presence of Art.

I have the ideas, but neither the tools nor honed skills. Sigh ... if you have the tools and skills, and can collaborate with a designer who understands the aesthetic (and the optics), you will together fashion an instrument that is truly one for the ages.

Ah, that I would travel to see!


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PhotoGazer
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Re: Round Wooden Tubes? new [Re: Tim A.]
      #4587901 - 05/17/11 11:39 PM

I am in the process of building three telescopes with wood tubes. One is based on the 127mm Carton optics from the surplus shed. The other two are Off Axis Newtonians. One will be a solid tube, and the other will be a two piece collapsible tube. I have been imaging the progress and will post links soon, I hope.

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Achernar
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Re: Round Wooden Tubes? new [Re: tim53]
      #5787169 - 04/08/13 11:46 PM

I like your refractor, the tube looks almost too pretty to load into a vehicle and drive out to the wildernss with it.

Taras


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