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Best approach for attaching rail angle iron

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#1 Lord Beowulf

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Posted 31 December 2012 - 12:27 PM

Hi All:

I've been debating back and forth about the best way to attach the angle iron for my V-groove wheels to the top of the rail. I'd originally planned to do it as shown on the left, which would require a lot of drilling and countersinking, etc. over about 140 feet of railing (2x 70 feet). What I realized though is that doing so eliminates any possibility of controlling the height of the rail, and if the screw goes in wrong, then the rail is being supported on the screw rather than flush on the wood base, which would most likely shear the screw (or bend it if I'm lucky) as the roof rolls over it.

Instead what I'm considering is what's shown on the right hand side of the picture. No countersinking would be required, and simple notches with an angle grinder would be enough to keep the rail from moving. I'd also have some level of vertical control for shimming or other adjustments to the rail.

So what have others done on their rails?

On a related note, what do people typically do for joining the segments of angle iron? I know I could weld and grind them, but that adds the possibility of warping, but more importantly adds the risk of burning down the observatory frame I just got built! That's something I'd rather avoid...

Thanks,

Beo

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#2 Gastrol

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Posted 31 December 2012 - 12:54 PM

I did my rails as illustrated on the right. Fast and easy, and the rails can easily be fine tuned for straightness.

#3 rimcrazy

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Posted 31 December 2012 - 01:40 PM

FWIW.....You realize you don't need V-Groove rails on both sides and in fact if you only put them on one side, it will prevent any binding you might get from differences in the distances between the rails for the 70' of travel. It does require that the flat rollers be larger and/or have a piece of flat stock to ride on so the height is constant but it completely eliminates any binding.

#4 jaddbd

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Posted 31 December 2012 - 01:52 PM

I ended up doing a little bit of both - mostly 'cause I got sick of breaking drill bits trying to drill holes thru the rails.... :smirk:

As far as the alignment, I just lined them up and put them together. I have one joint to rollover and you barely notice when it goes over the joint -no issues. We were extremely careful to make sure everything was very square and level with the walls and rail supports and it has stayed that way.... But I just noticed you are talking about a 70ft run of rail (wow!) so not sure if that presents an additional problem.

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#5 HunterofPhotons

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Posted 31 December 2012 - 02:06 PM

Here's a third option:
Weld flat crosspieces to the bottom of the track at appropriate intervals. Predrill oversize or oblong holes in the flat cross-pieces. That allows for easy installation and future adjustments. A lag screw with washer makes for a robust fastener.
Shimming under the unsupported areas of track will probably be required.
Welding lengths of track together is easy and strong. A proper weld won't distort the track. You don't have to weld them in place. Weld them near the observatory, grind as needed, and then lift into place.
I like to keep one section of track fastened down solidly and just snug down the 'follower' track to allow for seasonal changes, etc.

dan k.

#6 Gastrol

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Posted 31 December 2012 - 02:30 PM

FWIW.....You realize you don't need V-Groove rails on both sides and in fact if you only put them on one side, it will prevent any binding you might get from differences in the distances between the rails for the 70' of travel. It does require that the flat rollers be larger and/or have a piece of flat stock to ride on so the height is constant but it completely eliminates any binding.

Although the casters themselves have some lateral play in them that can prevent potential binding as they roll, what I did was let the other angle iron "float" on the beam, just secured only at both ends and at mid-length.

#7 Lord Beowulf

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Posted 31 December 2012 - 03:40 PM

FWIW.....You realize you don't need V-Groove rails on both sides and in fact if you only put them on one side, it will prevent any binding you might get from differences in the distances between the rails for the 70' of travel. It does require that the flat rollers be larger and/or have a piece of flat stock to ride on so the height is constant but it completely eliminates any binding.


Yeah, but that has its own problems with leveling, etc. Frankly with the size of the roof, I'd be more concerned about binding or twisting of the roof due to guiding it only on one side. With the length of the rail system, the wheels are going to have to have a small amount of side to side drift anyway even if only on one rail. The trick of course is that they can't drift so far that the capture rail rubs. I might have to add some side casters (probably should have planned on that to begin with) to keep things centered, but we'll see.

Beo

#8 Lord Beowulf

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Posted 31 December 2012 - 03:47 PM

I ended up doing a little bit of both - mostly 'cause I got sick of breaking drill bits trying to drill holes thru the rails.... :smirk:


I could easily avoid that if I use my drill press, but then that means handling 20' sections each. Not impossible, but not fun!

As far as the alignment, I just lined them up and put them together. I have one joint to rollover and you barely notice when it goes over the joint -no issues. We were extremely careful to make sure everything was very square and level with the walls and rail supports and it has stayed that way.... But I just noticed you are talking about a 70ft run of rail (wow!) so not sure if that presents an additional problem.


With 20' sections, it'll be four joints. It's just a question of the drift over time. I'm all about low maintenance!

Beo

#9 Lord Beowulf

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Posted 31 December 2012 - 03:58 PM

Here's a third option:
Weld flat crosspieces to the bottom of the track at appropriate intervals. Predrill oversize or oblong holes in the flat cross-pieces. That allows for easy installation and future adjustments. A lag screw with washer makes for a robust fastener.
Shimming under the unsupported areas of track will probably be required.
Welding lengths of track together is easy and strong. A proper weld won't distort the track. You don't have to weld them in place. Weld them near the observatory, grind as needed, and then lift into place.
I like to keep one section of track fastened down solidly and just snug down the 'follower' track to allow for seasonal changes, etc.

dan k.


Yeah, I'd thought of that too, although I was considering welding on tabs rather than a piece all the way across. That would certainly be stronger and straighter than the tabs idea (part of why I'd dismissed it) but has the side effect of elevating the angle from the face of the wood in that case. I could see cutting channels for the tabs, but that brings up water and rot worries! Choices, choices!

The tabs would certainly make it easier to let one rail float by using slotted tabs (more work slotting!). So is it better to float the rail vs. the wheels? That does give me a good idea though that I should have the wheels on one side with very little float to address any minor variations in a single rail, while allowing more float on the other side to allow for variations between rails.

Thanks,

Beo

#10 *skyguy*

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Posted 31 December 2012 - 04:40 PM

I tack welded the angle iron onto a length of steel square tubing and inside I welded some tabs (angle iron cut-offs) onto the square tubing to bolt the track onto the wood frame. You just need to be careful not to warp the track when welding. BTW, My observatory is 11 years old and I've never had a problem with this track design.

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#11 DGB

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Posted 31 December 2012 - 05:53 PM

Hello Beo,

I just posted in my Morning Calm thread on almost what you are contemplating! I had the "v" angle iron welded to a 5/16"x4" wide steel plate to the length required. This spreads the weight of the roof over a larger surface area and not have the bare "v" angle iron compress into the wall header plates.
http://www.cloudynig...5592040/page...
Here's another pic than the one I posted in my thread, showing the locking mechanism. I must have missed it, what dimension is your observatory going to be????

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#12 Lord Beowulf

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Posted 31 December 2012 - 08:11 PM

Hi Donovan,

Nice approach. That's a beefy bunch of metal there! Skyguy's square tubing isn't a bad idea either. Of course I could have taken that up to an I-beam and eliminated the need for the wood beams I'm building. A bit late in the design plan to change that far though!

You can see my Orion Ranch Observatory build thread for the details to date. The total observatory plus warm room length is 38 feet, and the roof needs to roll off about 28 feet to clear the eaves on the north side, so I'm putting about a 31' rail system for close to 70 feet total.

Beo

#13 jbattleson

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Posted 31 December 2012 - 10:58 PM

I cut a pocket in the top beam and let both angle iron rails float. Never had a binding problem. Rolls smooth as silk.

#14 Scott Horstman

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Posted 01 January 2013 - 01:34 AM

Figure A, the one on the left, off set as you have shown. You don't need to do anything for the butts other than be sure they line up. The 45 degree rollers are acually 46 or 47 degrees so to eliminate friction and there's really no big "bump" or anything when the wheels pass the joint. If you're using 2"x4" rollers and you drill the holes 3/8" from the edges, you don't need to countersink as the screw heads are well below the wheel.

You'll still have to look at it every year and do proper maintenence but if you do figure B, the one on the right, if the rails move it'll pop the angle iron right off and you may not catcht it. That could be bad.

#15 roscoe

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Posted 01 January 2013 - 10:28 AM

I have a small sawmill, that has a bandsaw head that rolls on rails, over the log to be cut. It runs on rollers same as a roll-off, and the angle iron track stands up in an L-shape. Much easier to drill and fasten down that way.
Russ

#16 Pat at home

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Posted 01 January 2013 - 01:18 PM

I have a small sawmill, that has a bandsaw head that rolls on rails, over the log to be cut. It runs on rollers same as a roll-off, and the angle iron track stands up in an L-shape. Much easier to drill and fasten down that way.
Russ


Good idea. I'll remember that next summer when I build a RoR.

#17 DeanS

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Posted 01 January 2013 - 07:40 PM

I bolted down a steel plate, then tack welded one angle iron on. then set the roof on with the other side angle iron loose, as we moved the roof it self centered and we tacked it as we went. Perfectly aligned. Pics can be seen on my website.

Here is a cadd drawing of the roller details, sorry about the poor quality.

Dean

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#18 Lord Beowulf

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Posted 05 January 2013 - 09:42 AM

Hi Dean,

I'm planning to do something similar to your keeper arrangement with wood. While I like the steel plate idea, that's a lot of extra expense without a lot of structural benefit. Looking back, it might have been more cost effective to do some square tubing like SkyGuy's setup, but too late now! The one thing that having all that steel would do is provide a smoother surface for a gasket or brush to slide along, minimizing the friction, but I'll have to make do! It also looks like you're running 6" wheels and 2" angle judging by the scale.

At any rate, I think I've decided that I'll probably be doing a mix of the two mountings shown originally, with about six through hole diagonal screws at ends and middle to minimize any chance of things "popping out" and the vertical wedge capture screws more often down the length.

Beo

#19 roscoe

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Posted 05 January 2013 - 09:55 AM

Referring to Beowolf's graphics, one could also put round-head - or pan-head - screws in at a 45 degree angle, so the heads were parallel to the angle-iron, with the bottom edge touching the wood.......
R

#20 Midnight Dan

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Posted 05 January 2013 - 10:31 AM

Hi Beowulf:

With your 70 foot run, you might want to give some thought to the difference in expansion rates between the wood and metal. The difference between their two coefficients is about .000005 inches per inch-degreeF.

Your run of 70 feet is 840 inches, which makes the overall expansion difference .0042 inches per degree F. If you figure a temperature difference between max summer heat and minimum winter cold of maybe 80 degrees F, then the end of your 70' steel rail will move back and forth a third of an inch relative to the wood. That's a lot!

Using through-holes at both ends would probably only serve to rip the screws out over time. For that long of a run, you might want to secure only one end and use the side screws for the rest so the rail can slide by them, or use some kind of bracket that captures the rail from the sides but does not hold it solidly in place. Another thing to consider is leaving expansion gaps between the rail segments. Of course that can cause bumpiness in the roof travel, and it may be difficult to keep the segments aligned with each other.

-Dan

#21 Lord Beowulf

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Posted 05 January 2013 - 10:36 AM

Thanks Dan:

I was actually referring to each of the 20' segments for the angle iron, not the entire span, and yes, I'll have to look at leaving at least some small gap and/or even slotting the holes on the sections. Of course at the moment I'm just as worried about the wood shrinking as it dries!

Beo






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