Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

ROR project questions

  • Please log in to reply
20 replies to this topic

#1 davidpitre

davidpitre

    Aurora

  • *****
  • topic starter
  • Posts: 4,782
  • Joined: 10 May 2005
  • Loc: Central Texas

Posted 05 December 2021 - 02:40 PM

I’m beginning a new ROR. Roughly 11’x 17’ with 6’ tall walls and a fold down south wall. Though I am new to observatories, I’ve got construction experience and am a good welder. Rather than dredge up a bunch of old threads with new questions, I thought I’d put my questions in a single thread. Thanks in advance.
1. I’m at a loss as to how to capture the roof so as to not lose it in high winds. I have seen large hook and eye bolts for when it’s closed. Any other ideas?
2. V groove track on one side vs 2 sides?
3. Most roofs seem to be asphalt shingles. It seems metal roofing has advantages. I’m wanting as low a pitch as possible. 12:1 with metal?
4. My roof will roll north and I am concerned with Polaris not being obscured. I thought about a hipped roof, but that precludes standard trusses. Ideas?
  • lee14 likes this

#2 macdonjh

macdonjh

    Fly Me to the Moon

  • *****
  • Posts: 7,117
  • Joined: 06 Mar 2006

Posted 05 December 2021 - 02:55 PM

I’m beginning a new ROR. Roughly 11’x 17’ with 6’ tall walls and a fold down south wall. Though I am new to observatories, I’ve got construction experience and am a good welder. Rather than dredge up a bunch of old threads with new questions, I thought I’d put my questions in a single thread. Thanks in advance.
1. I’m at a loss as to how to capture the roof so as to not lose it in high winds. I have seen large hook and eye bolts for when it’s closed. Any other ideas?
2. V groove track on one side vs 2 sides?
3. Most roofs seem to be asphalt shingles. It seems metal roofing has advantages. I’m wanting as low a pitch as possible. 12:1 with metal?
4. My roof will roll north and I am concerned with Polaris not being obscured. I thought about a hipped roof, but that precludes standard trusses. Ideas?

davidpitre,

 

  1. If you decide to use asphalt shingles, I'm not sure you need to worry about uplift from wind.  The roof for my much smaller 11'x11' observatory weighs approximately 2200 pounds (2"x4" framing, 1/2" or 3/4" OSB deck, felt, shingles).  As for fixing the roof when I'm not there, I use hooks and turn-buckles which hook into eye bolts.
  2. I used V-groove casters and inverted angle rails on both sides and haven't had any problems not created by my less-than-perfect framing.  In fact, while my roof was under construction the wind would blow it's skeleton from one end of the track to the other.  Once the sheathing and shingles were on, the wind wouldn't budge it, though.  I can see the advantage of only guiding one track, though.
  3. The consequence of asphalt shingles is the weight.  Good for resisting up-lift, perhaps bad for your back when opening and closing.  As you say, 1:12 is shallower pitch than recommended for asphalt shingles, too.  What about a flat roof with membrane sealer?
  4. I also roll north.  I have a simple gable roof (didn't want to learn how to frame a hip roof), gables on the east and west sides.  That didn't leave much framing on the north and south sides where the weight of the roof fell.  My initial attempt sagged.  I ended up installing some 1/4"x6" flat bar to reinforce the north and south ends of the roof.  That worked, but I should have seen that problem coming.

It sounds like your project and mine will have a few similarities.  You can see my observatory here: https://www.cloudyni...orly-lit-place/


Edited by macdonjh, 05 December 2021 - 09:52 PM.


#3 lee14

lee14

    Apollo

  • *****
  • Posts: 1,450
  • Joined: 19 Dec 2009
  • Loc: CNY

Posted 05 December 2021 - 03:35 PM

I'd think your main concern with high winds would be when the roof is closed. The local observatory where I used to do outreach, about 50% larger than yours, used a heavy duty turnbuckle at each corner. My personal ROR employs metal wheels in a 'C' channel, so they're captured vertically by default. When closed, a single peg slips through two eyebolts at one corner to prevent lateral movement. 

 

Asphalt shingles are indeed heavy, but there're no guarantee against strong winds (pictures of hurricane-detached roofs come to mind). Anchoring the four corners will be sufficient unless the wind is strong enough to damage the structure at large.

 

I used wood shingles to keep the weight down, but they're a high maintenance option. I'd never use them again. Metal is definitely the way to go. From your location I'd say snow is not much of a concern, so a low pitched metal roof will be fine. I would sheath the framing with 3/8 or 1/2 inch plywood though. 

 

If you design the roll off supports to accept the entire roof, access to Polaris should not be an issue. (unless your pier/mount is unusually low).

 

Instead of trusses, I used rafters and a ridge pole, without collar ties. More head room than a truss, and just as rigid. The building is almost thirty years old, and the joints are just as tight as when it was first built. Since yours is larger than my 10 x 12, you might add collar ties to give you the rigidity of a truss.

 

Lee


Edited by lee14, 05 December 2021 - 03:45 PM.

  • Jeff B likes this

#4 lee14

lee14

    Apollo

  • *****
  • Posts: 1,450
  • Joined: 19 Dec 2009
  • Loc: CNY

Posted 05 December 2021 - 03:50 PM

Roof detail.

 

roof detail.jpg

 

interior.jpg

 

Lee


  • Jeff B, Jaimo!, R Botero and 2 others like this

#5 greenstars3

greenstars3

    Viking 1

  • *****
  • Posts: 512
  • Joined: 20 Dec 2017
  • Loc: Wind River valley

Posted 05 December 2021 - 04:24 PM

I used V track wheels on both sides of my RoR and am very pleased with the system. As to the method of roof tie down I use chains and boomers (chain binders)

The roof was constructed using premade 12 ft trusses, sheeted with 1/2inch OSB and the building is just off North so I can align to Polaris 

The roofing I used is regular corrugated roofing like the type that you see on barns, the first time I installed the roof I used tar paper under the metal but I had very high heat gain from the roof, I took the roofing off and put a reflective layer under the sheet metal to cut down on the heat gain

Be sure to ventilate the structure, I have gable end vents using round 4 inch vents and the soffits have vents in them also, plus I have a 6 inch vent fan mounted in the north gable end on a thermostat that blows air into the building when needed so the hot air goes out the gable and soffit vents  

 

Robert



#6 davidpitre

davidpitre

    Aurora

  • *****
  • topic starter
  • Posts: 4,782
  • Joined: 10 May 2005
  • Loc: Central Texas

Posted 05 December 2021 - 10:05 PM

Another question. Is there any reason the 2 load bearing walls (the ones with tracks/casters) can’t be at different heights?

#7 mrlovt

mrlovt

    Viking 1

  • *****
  • Posts: 624
  • Joined: 08 Sep 2012
  • Loc: Smyrna, TN

Posted 06 December 2021 - 12:16 AM

I’m beginning a new ROR. Roughly 11’x 17’ with 6’ tall walls and a fold down south wall. Though I am new to observatories, I’ve got construction experience and am a good welder. Rather than dredge up a bunch of old threads with new questions, I thought I’d put my questions in a single thread. Thanks in advance.
1. I’m at a loss as to how to capture the roof so as to not lose it in high winds. I have seen large hook and eye bolts for when it’s closed. Any other ideas?
2. V groove track on one side vs 2 sides?
3. Most roofs seem to be asphalt shingles. It seems metal roofing has advantages. I’m wanting as low a pitch as possible. 12:1 with metal?
4. My roof will roll north and I am concerned with Polaris not being obscured. I thought about a hipped roof, but that precludes standard trusses. Ideas?

Congrats, you'll love having an observatory!  Here's what I've done:

1. Heavy duty u-bolt clamps.  They lock down and supposedly have a 2,000 lb capacity.  I figure a heavy wind will pull the roofing material off before it takes the entire roof.

2. Black pipe as a channel and brass u-wheels on both sides.  If I were doing v-channel I'd likely do the same just for simplicity's sake.  Frame it square and you'll be fine.

3. White PVC roofing because it's light, reflective, and easy to install.

4. 12:1 with PVC.  My roof is constructed similarly to Lee's posted above.  Extend the rails that the roof rolls out onto by whatever length you need to give you a view of Polaris.  Also, keep in mind that with PA routines such as in SharpCap, you don't actually HAVE to see Polaris from your observatory.

5. No reason I can think of other than ease of construction. If you have a need for two different height walls and can still make the rolling roof stable while accommodating different height walls on each side, go for it.



#8 t-ara-fan

t-ara-fan

    Vanguard

  • -----
  • Posts: 2,129
  • Joined: 20 Sep 2017
  • Loc: 50° 13' N

Posted 06 December 2021 - 03:04 PM

1. My observatory (12x18) is regularly exposed to 60mph winds. Many times a year.  The roof tracks are garage door rails that are a "C" in cross section. With a wheel every foot along the track.  The roof can't be lifted off. 

3. Asphalt on plywood will be VERY heavy.  My roof is steel sheeting on 2x4 trusses with a few 1x4 cross members.  Much lighter. The roof is white steel so cooler than dark asphalt.

4. Does your observatory have to be aligned with due north? Or can you make it NNE for example and get more clearance for seeing Polaris.  Or do some math and see if you will be able to see Polaris at ~32º waytogo.gif



#9 davidpitre

davidpitre

    Aurora

  • *****
  • topic starter
  • Posts: 4,782
  • Joined: 10 May 2005
  • Loc: Central Texas

Posted 06 December 2021 - 04:20 PM

I’m wondering if a 11 x 17 fairly lightweight roof will be difficult to roll off at 6 feet high. Are there any tips on reducing friction? Number of rollers per side? Quality of the bearing? Plastic versus steel casters on one side?

#10 lee14

lee14

    Apollo

  • *****
  • Posts: 1,450
  • Joined: 19 Dec 2009
  • Loc: CNY

Posted 06 December 2021 - 05:53 PM

I’m wondering if a 11 x 17 fairly lightweight roof will be difficult to roll off at 6 feet high. Are there any tips on reducing friction? Number of rollers per side? Quality of the bearing? Plastic versus steel casters on one side?

All metal rollers, no plastic. Metal will minimize friction, and there's no risk of degradation over time as with plastic. At least half a dozen on each side. It's simple enough to calculate the weight of the roof, and then use [ enough, and decent quality] a proper number so that each is supporting a fraction of its rated weight bearing load.

 

Lee



#11 macdonjh

macdonjh

    Fly Me to the Moon

  • *****
  • Posts: 7,117
  • Joined: 06 Mar 2006

Posted 06 December 2021 - 09:52 PM

+1: there is no engineering reason forcing the walls your roof will roll on to be the same height.  Everything just has to be square and level.

 

+1: more wheels on each rail reduces rolling friction because each wheel will have a smaller load on it.  Keeping the wheel bearings greased will also help.  I need to regrease mine.

 

I push and pull my roof with my arms above my head.  It's a bit of trouble to get going (static friction), but rolls pretty well once it's going (sliding friction in the bearings).  As I said, I need to regrease my wheels.  I only used six casters total, I should have used eight.  Several people I know have installed manual winches, electric winches, gate/ garage door openers, etc. to automate the opening and closing of their roofs.



#12 *skyguy*

*skyguy*

    Skylab

  • *****
  • Posts: 4,160
  • Joined: 31 Dec 2008
  • Loc: Western New York

Posted 07 December 2021 - 09:42 AM

Interesting comments on the number of wheels used to support a ROR.

 

I have a small garage rooftop ROR observatory .... inside dimensions: 5'7" x 7'2" ....  and it has only 2 V-wheels on each side. I believe they are rated at 800 lbs. each. The roof rolls of fairly easily and I've never encountered any problems over the past 20 years of use.

 

Good Luck on your observatory build ...

 

https://www.flickr.c...57644177074161/

 

Home Observatory Inside.jpg

 

Obsevatory_wheel_and_turnbuckle_CN.jpg



#13 greenstars3

greenstars3

    Viking 1

  • *****
  • Posts: 512
  • Joined: 20 Dec 2017
  • Loc: Wind River valley

Posted 07 December 2021 - 03:52 PM

Great suggestions on the wheels - keep them lubricated and they roll( mine have grease fittings on them) - I have ropes attached to both ends of my roof and pull it open and closed with them

I know that some have automated the opening and closing of the roof, as my RoR is not used as a remote obs for imaging I find the idea of automation for roof opening and closing a complexity not needed for my use. Of course YMMV 

 

Robert 


  • dhkaiser likes this

#14 Jeff B

Jeff B

    Cosmos

  • *****
  • Posts: 8,252
  • Joined: 30 Dec 2006

Posted 08 December 2021 - 12:23 PM

David, congrats on your project.

 

I highly recommend metal roofing primarily for its lower weight compared to shingles.  Big hooks and/or turnbuckles are all you need to keep the roof from moving even with high winds.

 

My wheel and track hardware is actually used primarily for sliding gates but is perfectly suitable for a ROR observatory.  I have two sources:

 

L.A. Ornamental:

 

https://laornamental...atalogb97d.html

 

for the wheels

 

https://laornamental...olling-6ft.html

 

for the track

 

Architectural Iron Designs Inc:

 

https://www.archiron...ove-wheels.html

 

for the wheels

 

https://www.archiron...oove-track.html

 

for the track.

 

I have to tell you that I had issues working with LA Ornamental and had to file a claim with Paypal.  They eventually got the hardware (wheels and AL track) to me and it is of high quality. 

 

I had no difficulties at all with AIDI (4" V groove wheels).  Their prices are slightly higher than LAO, but they shipped promptly.  They were also fascinated by my application and want me to send them pictures of my installation.

 

BTW, I have a brand new spare set of 20 (or two sets of ten) 3" steel, sealed bearing  V groove wheels that I will be selling.  If you are interested just PM me.

 

Show us pictures! 

 

Jeff


  • lee14 likes this

#15 DeanS

DeanS

    Aurora

  • *****
  • Posts: 4,741
  • Joined: 12 Jul 2005
  • Loc: Central Kentucky

Posted 08 December 2021 - 12:33 PM

I did hip roof so I could see Polaris with the roof gable not in the way. 

 

Angle iron on both sides.

 

You can see construction pics on my old website.

doghouseastronomy.com


  • Jeff B likes this

#16 techmgr

techmgr

    Apollo

  • -----
  • Posts: 1,014
  • Joined: 31 May 2003
  • Loc: North Central Ohio

Posted 08 December 2021 - 01:30 PM

On my first ROR, Backyard Observatories used turnbuckles on each corner of the roof - a bit of a pain in the backside to remove them whenever you want to roll back the roof.  They changed their approach at some point and on my 2016 built ROR they use three brackets on each side that prevent the roof from lifting - picture attached, although it doesn't really show much detail on the bracket.  I have a metal roof over plywood sheeting - much lighter than a sheeting/shingle roof.  Both of my ROR's had the v-track on both sides and both roofs rolled off to the north.  No problem sighting Polaris from about 40.9N. You can get an idea of the roof pitch from the picture - not sure exactly what it is. Also, the first ROR had six foot walls, which meant a standard door couldn't be used.  BYO changed to seven foot walls to allow the use of a standard door.

Attached Thumbnails

  • Roof Retention.jpg


#17 Jeff B

Jeff B

    Cosmos

  • *****
  • Posts: 8,252
  • Joined: 30 Dec 2006

Posted 08 December 2021 - 04:41 PM

I did hip roof so I could see Polaris with the roof gable not in the way. 

 

Angle iron on both sides.

 

You can see construction pics on my old website.

doghouseastronomy.com

Dean, how in the heck are you?  You and your family doing well I hope?

 

Nick and Jen have moved down to KY.

 

Jeff



#18 Galaxyhunter

Galaxyhunter

    Mercury-Atlas

  • *****
  • Posts: 2,893
  • Joined: 02 Jan 2006
  • Loc: Northern Illinois

Posted 08 December 2021 - 05:27 PM

For the roof lifting off, I did this. These are on the South side,  The North side has this. When the roof is closed, it automatically holds the roof down so there's no need to eye hooks or turn buckles.

I have a steel roof which is much lighter and WAY less mass to hold the heat.  There is no reason you can not have two different wall heights.  As far as effort to roll the roof, use steel casters, they have far less

rolling friction.  My roof is 14 x 16 with inverted iron on both sides. 5 casters on each side.  When I built it, I hooked up a pull scale and it took 70# to start moving it & 50# to keep it going.


  • kolsen, archer1960, t-ara-fan and 1 other like this

#19 archer1960

archer1960

    Viking 1

  • *****
  • Posts: 955
  • Joined: 26 Jul 2011
  • Loc: Southern New England

Posted 09 December 2021 - 11:01 AM

For the roof lifting off, I did this. These are on the South side,  The North side has this. When the roof is closed, it automatically holds the roof down so there's no need to eye hooks or turn buckles.

I have a steel roof which is much lighter and WAY less mass to hold the heat.  There is no reason you can not have two different wall heights.  As far as effort to roll the roof, use steel casters, they have far less

rolling friction.  My roof is 14 x 16 with inverted iron on both sides. 5 casters on each side.  When I built it, I hooked up a pull scale and it took 70# to start moving it & 50# to keep it going.

So ingenious yet so simple!



#20 stargzr66207

stargzr66207

    Viking 1

  • -----
  • Posts: 664
  • Joined: 28 Aug 2014
  • Loc: Kansas, USA

Posted 11 December 2021 - 10:54 AM

My roof is 12/4 pitch and covered with 16 gage corrugated steel. No problems in 18 years!
Roof tie downs are “over center” type barn door latches. See details at www.astrolandofoz.com
Ron Abbott

#21 ram812

ram812

    Apollo

  • -----
  • Posts: 1,462
  • Joined: 10 Dec 2014

Posted 14 December 2021 - 12:51 AM

I had drifted the idea of using skateboard wheels with German racing bearings, which are quite fast when used as designed😯, but c-channel will keep the roof planted...metal is really the light weight material of choice for the roof, though I hear flat panel PVC of various thickness is used on some folks obsy roofs.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics