RoR track...thoughts please

[Gina]

If you're concerned with rigidity Gina then you might be able to put some sort of tie bar in the dividing wall? You could even perhaps use a length of your runner material appropriately cut and bent over to form a 90 degree flange at the end, bolted through the top member of the wall.

It's the rigidity of the roll off section that I'm slightly concerned about. I'm happy that I can make the walls rigid using diagonal bracing. I'm using 3x2 (75x47mm) for the main members which I think will make a pretty strong and rigid base structure.

I'd have thought that merely having an angled section on the top of the wall would help with rigidity no matter which way it faced. One might, I guess, argue that having the upright on the outer side would actually stress the wall outwards more, because any sideways load imposed by the roof is going to be pushing the wall outwards?

James

Again, I think 3" wide timbers will give plenty of sideways rigidity even with 8' spacing of the obsy walls. Yes, the angle track will add yet more rigidity.

[Gina]

Put the wheels on the bottom (walls) and the track on the top (roof) - nothing can get stuck in the track that way.

Yes, I thought of that but I figured that exposing the wheels and bearings to the weather was not a good idea. The track being corrosion resistant grade aluminium would not suffer from exposure to the weather etc. I don't want dirt getting in the wheel bearings either. Dirt on the track (or the "wrong sort" of leaves) isn't such a problem.

[Gina]

Just means twice the amount of wheels needed, half of which will be exposed to the weather: Result rusty wheels.

Absolutely! Though in my case the wheels won't rust being nylon. However, the axles are stainless steel bolts and are subject to surface rust. But up inside the roll off framework the wheels and axles will be well protected from the weather and even wind-blown dust to a large extent. I plan to apply a light coat of grease to the axles to reduce wear on the wheels.

[Gina]

A good point on the amount of wheels, but would you be opening the roof if there is weather to consider?

With wheels on the bottom (base part), only half the wheels would be inside when the roof is shut. The others would be outside in the elements.

[RogerTheDodger]

What elements? would you open the roof in rain?

[Gina]

What elements? would you open the roof in rain?

No but the roof rolls out into the open. The "open" part is only covered up when the roof is open. Maybe a diagram would help

Or have a look at photos of completed builds... There is even an animation of how one roof rolls off over the exposed section.

[RogerTheDodger]

Ahh... penny drops

[JamesF]

It's the rigidity of the roll off section that I'm slightly concerned about.

Ahhh, right, I see. That is more of an issue I can see, as you want it as light as possible to make it roll easily, but strong enough not to deform under its own weight. If belt and braces are required then perhaps a few eye bolts and some diagonal runs of heavy gauge wire or steel cable could be used internally to stop the sides splaying.

I can't wait to see your sketchup model. I've done mine twice already (at nowhere near the level of complexity that yours appears to be from your screenshots) and changed my mind about layout as a result. I'm going to try another arrangement this evening, since it doesn't look like there'll be much visible to trouble a scope with tonight.

James

[fwm891]

I use a well known shelf support track (might be well known but I can't think what its called!!!).

This I have mounted upside down and run 50 mm rubber wheels along it. It has pairs of slots along its length for the shelf supports to slot into to there's nowhere for water to accumulate.

Unlike most RoR I don't have a fixed outer track due to space around the obsy so I clip my extension tracks to the end of the obsy before observing and take them back into the obsy afterwards... see Fitzroy Observatory photos in this section http://stargazerslounge.com/diy-observatories/147917-fitzroy-observatory-shed.html .

Francis

[malc-c]

A good point on the amount of wheels, but would you be opening the roof if there is weather to consider?

In a normal ROR design the wheels are fixed to the rolling roof, thus all concealed inside the part that's moving. If the wheels are to be static so the roof rolls on them (much the same way as those roller conveyors) then the section the roof is to roll onto, be that over a warm room like mine, or two support rails, will be open to the elements, even when the roof is closed

[malc-c]

Sorta missed some of the other posts when I jumped in here !

My thought was that most of the cheap wheels tend to have steel shafts and frames. You could use nylon wheels with stainless bolts fitted into a wooden framework but then leaves etc could build up in the gaps and stop the wheels rolling.

I don't think there is any ideal way, each has advantages and disadvantages...

[Gina]

Ahhh, right, I see. That is more of an issue I can see, as you want it as light as possible to make it roll easily, but strong enough not to deform under its own weight. If belt and braces are required then perhaps a few eye bolts and some diagonal runs of heavy gauge wire or steel cable could be used internally to stop the sides splaying.

Unfortunately not It has to clear the warm room roof.

I can't wait to see your sketchup model. I've done mine twice already (at nowhere near the level of complexity that yours appears to be from your screenshots) and changed my mind about layout as a result. I'm going to try another arrangement this evening, since it doesn't look like there'll be much visible to trouble a scope with tonight.

James

I can post the part completed SketchUp model if you like. I have learnt a lot by going through the training videos and studying the help, learning what the menu options do etc. I have found a lot of short cuts and easier ways of doing things. I'll be happy to post some hints and tips for things I've found particularly useful. There is already a thread devoted to SketchUp so I'll post hints and tips there if this would help people.

[Freff]

Sorta missed some of the other posts when I jumped in here !

My thought was that most of the cheap wheels tend to have steel shafts and frames. You could use nylon wheels with stainless bolts fitted into a wooden framework but then leaves etc could build up in the gaps and stop the wheels rolling.

I don't think there is any ideal way, each has advantages and disadvantages...

This leads back to my original thoughts on the round track and pulley wheel rather than channel and castor.

If it wasn't for the noise I would consider inverted equal angle aluminium and V wheels.

[Carbon Brush]

To avoid wheel carrier rusting, I bought stainless carriers with nylon wheels. These are intended for food trolleys. I also bought a couple of extras so if I get any failures in years to come I can do an immediate change.

[jpdavies]

For my ROR I used 2" rubber tyred castors running along the top surface of the wall structure. Lateral movement is constrained by L-shaped aluminium angle running the whole length of the observatory (16 feet). Over three years I have had no problems. I am now thinking of replacing the castors with ball-bearing races which would have much less friction.

[laser_jock99]

For my ROR I used 2" rubber tyred castors running along the top surface of the wall structure. Lateral movement is constrained by L-shaped aluminium angle running the whole length of the observatory (16 feet). Over three years I have had no problems.

Sounds pretty much like what I'm planning. I made a mock up today of the roof rollers and it seemed to be quite smooth. Hope it's the same with 150 kg of roof on top!