Does any one know where you can get Plans to build a G.E.M. to hold a 15 O.D. Newtonian Telescope. or Where you could buy one. Every Where I look all I see is ones for Schmidt-cassagrains or Refractor that claim to be heavy duty. The Weight of the Telescope with is about a 100lbs so I would assume it would need to hold 200lbs with the counter weights.

WOW!!  That's a tall order.    Regardless of the design, you're going to have to be either a master woodworker or top-notch machinist -- probably both -- if you are going to make something like that!!  If you have never made a telescope mount before, I would caution you against beginning with something so ambitious.

Have you considered making a Dobsonian mount for the scope?  Unless you are contemplating guided astrophotography, that would be a much easier, and probably sturdier, way to go.  There are plenty of plans for Dob mounts on-line as well as in print, which you could adapt to your needs.  Do a Google search for the San Francisco Sidewalk Astronomers.  They have a good set of plans on their web site.

If you're still set on a GEM of some sort, the best way to learn is to review what others have done.  I'd recommend that you take a look at the photos from previous Stellafane conventions, available at http://www.stellafane.com.  Once you see what others have done, it might give you some idea as to what you can do.

Very few commercial mounts will support that much weight or that long a moment arm.  I'd recommend looking into the Losmandy HGM Titan, possibly the Astro-Physics 900, the Parallax HD150C, and the Takahashi EM-500 Temma II.  But be sure you're sitting down before you check their prices.

Good luck!!

I keep looking but I don't seem to find any complete plans w/dimensions on the web.

There is a nice on in Richard Berry's book "Build Your Own telescope."

I'll keep looking and if I run across one I'll post it.

I have the same problem.

I came across one setup using galvanized pipe, but did not say how they built the bearing for the Head Unit...

I hesitated sending this because the picture is all I have, but it might be useful to you.

 

Lets try this again, hopefully here is the pic.

http://i5.photobucket.com/albums/y183/LargeSarge/pipemount.jpg

I remember seeing this plans years ago, I did not no were I had seen them…

 

Thanks for the Input…

I just got done making an equatorial mount for my six inch newt.  It is not nearly as sturdy as I thought it would be.  I have not mounted the scope on it yet, hopefully the weight will help calm it down a bit.  I had some scrap aluminum I-beam that I used to make most of the actual mount out of and I used treated 2x4's for the legs.  For the rotation, it is merely the movement alloted by the thread in the pipe.  I plan to either redesign and build another, or work some kind of adjustment capability into this one. 

For a 100 lb. scope you need to build a mount with a suggested load capacity of at least 400lbs. That is to say, a mount needs to easily support double the weight of the scope and counterweights, for it to be an effective mount for astrophotography. For visual work only, a 300 lb. load capacity would be fine. Make friends with someone who has a CNC milling machine, as finding some of the 'off the shelf' parts could be challenging. Access to auto salvage yard - drive shafts, transmissions with planar gears, etc..- could be a way to be creative and cut costs.

 WAlkey,

Let me know if you find one. I've got a 14.5" folded newt that weighs in at 110#. A Titan isn't big enough to handle it. You (we're) looking at something along the line of an Astro-Phyics AP1200GTO  or Astro-Physics 36000GTO  The 1200 will set you back $9400 plus any accessories. The 3600 hasn't had it street $ set yet.  I think I'm going to have to go the s Alt/Alz setup just to keep the $ and engineering down to a sane level.HTH

T-Man.
 

There is the Paramount ME from Bisque. It can handle 150 lbs.

http://www.bisque.com/help/paramountme/Paramount_ME.htm

And an offering from Meade.

http://www.optcorp.com/product.aspx?pid=439-278-7838

Hi,

Have you considered building some variation of a split-ring equatorial. That may be a bit easier to build than a large GEM-only a suggestion.

Good luck with your project.

Bill

You might see if your local library or bookstore has "Building & Enjoying Telescopes", by Robt. Miller & Kenneth Wilson. I has plans for an extremely sturdy rough-and ready GEM for an 8" Reflector, but, from the looks of it, it could hold 50 lb easily (!). Also, take a look here:

http://solar.physics.montana.edu/larson/Capella/index.html

Good luck!

Alton

I think what you want is one of Pierre Schwaar's Big Foot designs. I know that some plans were available years ago via the Saguaro Astronomy Club, but I do not know how to get them now.

I have a friend who owns one. He has two scopes for it: a 13" and a 16", and both are also fairly long.

I don't know how many Pierre made, nor how many others may have copied them. But the design is straightforward.

They look like this (that's a 14-inch newt):

Each of those counterweights is about 50 lb. and the counterweight shaft, itself, is about the same. My friend's BigFoot will track for about two hours before resetting. The RA drive gear is on the arc of a 40-degree section of a circle, so you track for a while, then reposition (as with a dob's EQ platform), then restart. The DEC head rotates 360 degrees, though with a scope mounted like this you wouldn't be able to go the full circle.

The typical mode of observing with these mounts is to observe for a couple of hours on one side of the meridian, then swap to the other side when you reset the mount.

The photo above is one of several from here. You might contact those folks to find out if plans, or close-up photos showing the mount's operating principles, are available. They're in Arizona and use some of Pierre Schwaar's equipment for outreach programs. Mr. Schwaar, a pioneer member of the SAC, died in 2000.

I have a similar problem. I have inherited a 14.5" f10 folded newt. (yeah 3 METER focal length!) The Coulter primary weighs 65# add in the 4.5'" secondary, diagonal, spiders & the OTA comes in at 110# and 2 meters long. Gianormous
I can't find ANYTHING that I can afford and still AP. The closest is a AP & it runs around $12-13k without a tripod or pier. I had build a drive for it for Shoemaker-Levy out of 3/4" Ply but it was so bad it didn't survive the day. The OTA & Drive part have been sitting on my porch since waiting for me to find/make something that will actually work. FWIT think BIG heavy-duty bearings and pillow blocks. I wouldn't even try to put this on a tripod again. Waaaay too much mass. A semi or permanent pier with a solid footprint is an absolute must.

 

Well if you want to equatorially mount a heavy scope using cheap technology, you might consider the split ring. It's great strenth is that all the stress within the mount are in compression. I have constructed an 18" split ring equatorial for about 400 dollars. I used wood. It weighs in at about a 1/4 ton yet rolls on wheels. It is very stable. It has a 5' equatorial disc about 2" thick. It uses skate board parts for the the rollers and drive. For the declination axis large pipe flange (12") and uhmw plastic do the job. There is a sixty pound counterweight behind the mirror. The reinforced cardboard tube rotates on 2' rollers inside a box. For tools I used a 10" table saw, drillpress, carpentry tools, and salvaged wood. Merit award winner Riverside 1989. 

Split ring types seem to get little notice here and are generally under appreciated by most amateurs. Part of the reason may be because they're only suitable for certain optical systems. For accuracy and load bearing ability they can't be beat.

A 60" ring for your 18" mirror? Sounds nice.