AstroArlo
sage
Reged: 01/29/06
Posts: 419
Loc: Jackson Hole, Wyoming
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I'm curious where people find the angle iron track to use with V-groove casters.
Is this available pre-welded (angle iron on flat iron), or do you have to buy angle iron and flat ribbons of iron separtely and have them welded together?
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Best Regards, Arlo
Grand Cosmic Observatory, Jackson Hole, Wyoming
CATS/CASS - 20" RCOS Ritchey-Chretien, C14, C8
REFRACTORS - 155mm Astro-Physics Starfire EDF w/4" Focuser, 102mm Televue Genesis, 78mm FS Takahashi
ASTROGRAPHS - 8" Lichtenecker Flat Field Camera, 6" JSO Schmidt Camera
MOUNTS - Paramount ME, Losmandy GM200, Takahashi EM-100
CCD/IMAGING - SBIG STS-4, SBIG STL-11000M
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pbealo
super member
Reged: 10/12/06
Posts: 126
Loc: New Hampshire
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Angle iron is kind of a standard stock item at many metal fabrication shops. What we did for my observatory was to weld two pieces of angle iron like this:
11 /\
__/ \__
l
l
l
Sorry, I couldn't make a 90 deg angle with slashes...
The horizontal and vertical parts were just attached to a wood beam.
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PeterB
15" fecker cass
12" Fecker cass
6" Fecker Celestar
4" Fecker Celestar
4"/4" dual tube Brashear
Porter Garden telescope
3.5" Mogey
Quantum 6
Quantum 4
6" AP Starfire
misc. smaller stuff
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MichaelW
Carpal Tunnel
Reged: 06/03/06
Posts: 1538
Loc: Cartoon City, Nirvana
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Any steel supplier should be able to get you what you need. You could weld it together and weld id down to your mounting plates, which is probably preferred. But I am sure you could also screw it down in place and that too would work as the angle/v-caster mounting isn't holding the rood down as much as your latching mechanism is.
Note, I used V-casters on my dome but used 0 gauge wire as my angle since it was in a circle and not a straight line.
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Michael W
Washoe Zephyr: 
Arizona Sky Village: 
I miss my AP1200. 
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Tom Clark
sage
Reged: 11/14/07
Posts: 248
Loc: Chiefland, Florida
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V-groove wheels are also designed to run on the edge of angle iron, with either the wheel on top or underneath. You can run them on the side of angle iron, but they produce higher friction in that manner.
This photo shows a close-up of my dome track.
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Tom Clark
sage
Reged: 11/14/07
Posts: 248
Loc: Chiefland, Florida
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I had the three-inch angle rolled into the diameter my dome required, and had it welded in place - after measuring it many times to make sure that it was round within 1/4".
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csa/montana
Wild Spirit
Reged: 05/14/05
Posts: 40257
Loc: montana
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Mine (from BYO observatories) was one piece (not welded together). It was screwed down in place, & sections were simply butted up against each other.
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Carol
AstroTech 16" Dob (Thanks ASTRONOMICS!)
Vixen 80MF/AstroTech Voyager
Masuyama's 7.5, 15, 25W, 35mm,
Pentaxes; 5XW, 7XL, 10XW.
14mm Meade 4000 UWA
TV Panoptics; 22, 35
DreamCatcher Dobservatory, #2
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soreneck
scholastic sledgehammer
Reged: 04/01/06
Posts: 920
Loc: Toronto, Canada
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Hi Arlo,
For my roll-off design, I went with a simple L-channel angle iron, inverted to make a V. It was the cheapest solution I could find. I secured the angle-iron to the 2x10 rails using screws and washers. So far it has proved more than sufficient to handle the weight of my small roof.
Unfortunately I can't find a detailed photo, but this one is the closest I can manage. (The observatory roof and support beams were unfinished at that point, but it illustrates the channel.)
Hope this helps.
Cheers,
Adam
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Adam
WO 110 FLT / WO 66 Triplet
QHY9 / Modified Canon 450D
SkyWatcher EQ-6 Pro
Backyard (urban) roll-off observatory
One small but fearless dog (observing companion)
my astrophotos on flickr
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f29pc
professor emeritus
Reged: 05/23/05
Posts: 651
Loc: Maine
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Here is how I did mine. I got the matirial from the local fab shop.
http://www.burkesobservatory.com/showPic.php?id=45&&cls=O
Paul
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12" LX200 UHTC OTA
10" LX200 EMC
WO 105mm APO, 80mm APO, 66mm APO
MI250
Next day air makes every night X-mas eve!
www.burkesobservatory.com
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kiwisailor
Pooh-Bah
Reged: 01/07/04
Posts: 1221
Loc: Lyttelton, New Zealand
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Quote:
I used V-casters on my dome but used 0 gauge wire as my angle since it was in a circle and not a straight line.
Neat idea Michael, did you spot weld the wire to a continuous base plate or series of plates spaced out round the wire circle?
Any fabrication/general engineering shop should be able to help you out Arlo, or track down your nearest supplier of mild steel bar and angle iron, if you want to DIY
Steve
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Don't wait until tomorrow, start procrastinating today!
Sky-Watcher 8" F5 Newt
Mmmm Moonlite CR2
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MichaelW
Carpal Tunnel
Reged: 06/03/06
Posts: 1538
Loc: Cartoon City, Nirvana
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Quote:
Neat idea Michael, did you spot weld the wire to a continuous base plate or series of plates spaced out round the wire circle?
Thanks Steve.
No, I placed the cable in a routed channel in my plywood base ring on a bed of adhesive and nailed down with small tacks through the middle of the cable down to the base ring. The weight mostly rides on the base plate and the cable is more of a guide. I can't take credit for the concept though, I got it from the Autopia ride at Disneyland in CA. The cars drive around like cars but there is a steel "track" to limit the wanderings of the "car".
This is how I will also guide my roll off roof. Easy to install and the materials are cheaper. 
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Michael W
Washoe Zephyr:
Arizona Sky Village:
I miss my AP1200.
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kiwisailor
Pooh-Bah
Reged: 01/07/04
Posts: 1221
Loc: Lyttelton, New Zealand
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Quote:
No, I placed the cable in a routed channel in my plywood base ring on a bed of adhesive and nailed down with small tacks through the middle of the cable down to the base ring
It just gets better  , seems like an ideal solution for a lightweight dome or ROR obs
Quote:
I can't take credit for the concept though, I got it from the Autopia ride at Disneyland in CA.
Imitation is the sincerest form of flattery
Thanks for sharing the idea.
Steve
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Don't wait until tomorrow, start procrastinating today!
Sky-Watcher 8" F5 Newt
Mmmm Moonlite CR2
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kiwisailor
Pooh-Bah
Reged: 01/07/04
Posts: 1221
Loc: Lyttelton, New Zealand
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Thinking about tracks, how about using 3/4 Galv pipe as a track.
For ROR's, you could rout out a small channel, bed it in Epoxy and drill through the pipe and screw it. You'd need V-groove castors with a suitable profile, there would only be two points of spot contact, so rolling drag would be minimal.
For domes, the pipe would have to be bent, (but so does angle iron)and Galv isn't flash to weld (spline it with a bit of Mild Steel rod turned to match the pipe ID?) and fix down the same as for a ROR.
Steve
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Don't wait until tomorrow, start procrastinating today!
Sky-Watcher 8" F5 Newt
Mmmm Moonlite CR2
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 12941
Loc: Amargosa Valley, NV, USA
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Quote:
Note, I used V-casters on my dome but used 0 gauge wire as my angle since it was in a circle and not a straight line.
Michael, is that copper wire or aluminum? Is it less costly than angle iron?
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"Since the process of science generates more mysteries than it solves, I predict that we'll never learn everything: and we'll continue to generate new ignorance at the speed of knowledge."
"S.O.E." (Sauron's Other Eye), with 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Under Construction: The "Eye of Sauron" Observatory!
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MichaelW
Carpal Tunnel
Reged: 06/03/06
Posts: 1538
Loc: Cartoon City, Nirvana
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Thanks!
You could use almost anything (I'm sure) to guide the wheels and pipe should work as well.
I used copper encased in a plastic shield but only because that's what they had at the home store and it added some diameter over bare wire. I took one of the casters down to the store and purchased the wire that best fit the groove. I'd imagine that either copper or aluminum would work equally as well. Both are equally soft but the design isn't to ride on the wire but the base and use the wire as a guide.
In my case where I needed a large diameter circle for a rotating dome, the angle iron was one price the other price was getting the correct bend in each piece to match my dome. But even in a straight application copper would be cheaper if memory serves. I went into the store to see what size I needed or you could use a chart. I think I spent about 30 bucks in wire and I needed 10'x3.14(etc). So at the time I was looking at about a buck and change a foot. Angle iron is a tad over that.
The drawback to this concept is in places such as where I live, where you would need to ensure the track is clear before you roll because in the case of snow or ice build up you could "jump the track". Whereas a angle iron track tends to shed the snow from the track.
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Michael W
Washoe Zephyr:
Arizona Sky Village:
I miss my AP1200.
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polaristom
super member
Reged: 12/17/07
Posts: 157
Loc: Alaska
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Careful, 3/4" pipe is the inside diameter and will be too large for your casters. I used 1/2" pipe for my shutter assembly and it worked great. 1/2" pipe is about 7/8" outside diameter.
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5025
Loc: Mobile, Alabama, USA
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You can buy angle iron, which is really steel, at many home improvement centers and steel supply shops. I would contact a local steel supplier because you'll be using a good bit of steel and the prices are better. You could also try searching for what you need at a scrap yard. It is preformed so no welding is necessary, which would be time consuming and laborious because it would have to be fitted carefully so after welding the wheels would roll in the track properly. Just select the size and thickness you need. Cutting angle iron with a hack saw is possible, but slow. I would borrow or buy a saw such as a reciprocating saw called a "Sawz All" or a portable band saw, and buy a package of blades suitable for the metal you'll be cutting. Or get measurements ahead of time and have the shop cut the angle iron to length for you.
Taras
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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
Two curious cats
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HunterofPhotons
sage
Reged: 04/26/08
Posts: 266
Loc: Rhode Island, USA
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I had a metal working shop order some galvanized angle iron. They welded two pieces together to make the long lengths that I needed, tacked on some drilled mounting feet, and delivered them to my house for a reasonable cost.
You might be interested in this alternative to metal track wheels:
polyurethane wheels .
They're quiet and they don't rust. Of course, they're more expensive <g>, but not by a lot.
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csa/montana
Wild Spirit
Reged: 05/14/05
Posts: 40257
Loc: montana
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I've never been bothered by what little noise the wheels make rolling the roof off. I also would question the strength of the polyurethane wheels with extreme temps; way below zero, for instance. 
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Carol
AstroTech 16" Dob (Thanks ASTRONOMICS!)
Vixen 80MF/AstroTech Voyager
Masuyama's 7.5, 15, 25W, 35mm,
Pentaxes; 5XW, 7XL, 10XW.
14mm Meade 4000 UWA
TV Panoptics; 22, 35
DreamCatcher Dobservatory, #2
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HunterofPhotons
sage
Reged: 04/26/08
Posts: 266
Loc: Rhode Island, USA
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Quote:
I've never been bothered by what little noise the wheels make rolling the roof off. I also would question the strength of the polyurethane wheels with extreme temps; way below zero, for instance.
The noise from my metal wheels is minimal, too. Not at all objectionable in my opinion.
The temperature range for the polyurethane is -40° to +200° F. I usually close up shop for the night when the temperatures get outside that range anyway. <g>
dan
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kiwisailor
Pooh-Bah
Reged: 01/07/04
Posts: 1221
Loc: Lyttelton, New Zealand
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Just been reading "Standard Handbook For Telescope Making-N.E. Howard, ISBN 0-690-76784-6" which has a chapter on Observatory building.
The author gives his opinions on tracks, and how to bend angle iron into a curve by rough hand bending and then a final smoothing into the final desired curve using a hardwood former cut to match the required final curve (2 foot long *2" thick- with a flat iron "shoe" screwed to the curved surface)The curve is faired up by using the Hardwood former as a dolly and hammering the roughly bent angle iron against it, checking the results regularly against a full size circle laid out on a suitable concrete floor.
Howard goes on to say that with sufficient patience and elbow grease, you can come within 1/4 of an inch of a perfect circle.
Steve
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Don't wait until tomorrow, start procrastinating today!
Sky-Watcher 8" F5 Newt
Mmmm Moonlite CR2
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DeanS
scholastic sledgehammer
Reged: 07/12/05
Posts: 954
Loc: Nicholasville, Kentucky
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Here is a drawing of how I did mine. It is spot welded to the steel top plate.
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AP1200GTO AP900GTO
TOA-150 Tak E160
C9.25 Tak FS60C
SXV-H9 ST2000XM STV
8" LX200GPS
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www.doghouseastronomy.com
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AstroArlo
sage
Reged: 01/29/06
Posts: 419
Loc: Jackson Hole, Wyoming
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Thanks everyone for all the great ideas.
I've had my roll-off for 3 years now. I just used flat rollers on doubled 2x6's. It's worked OK, but the 2x6's are starting to warp and split, and the roof is now at a very small angle to the 2x6's. I'd also like to automate the roof, so I'll need a motor and some gears - this obviously won't be possible unless the roof rolls along a consistent path.
So, I need to retrofit the rails to my existing roof. My wheels are located in the traditional place - attached to the bottom of the roll-off roof. But the diagram of the rotating dome gave me the idea of mounting the wheels to the wall, and the rails to the roll off roof. This may be a simpler retrofit than putting the v-coasters on the roll-off roof and the angle iron on the wall.
I'll have to think about this for a while. I have the obvious problem of supporting or lifting a one ton roof while I am retrofitting the angle iron and v-coasters.
So, anyone who is contemplating a roll-off, don't make my mistake with just plain rollers on 2x6's. You should definately get some type of track system.
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Best Regards, Arlo
Grand Cosmic Observatory, Jackson Hole, Wyoming
CATS/CASS - 20" RCOS Ritchey-Chretien, C14, C8
REFRACTORS - 155mm Astro-Physics Starfire EDF w/4" Focuser, 102mm Televue Genesis, 78mm FS Takahashi
ASTROGRAPHS - 8" Lichtenecker Flat Field Camera, 6" JSO Schmidt Camera
MOUNTS - Paramount ME, Losmandy GM200, Takahashi EM-100
CCD/IMAGING - SBIG STS-4, SBIG STL-11000M
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