Astrokev's Obsy Build

[Gina]

My roll off uses 100mm rubber tyred wheels with needle roller bearings. I got mine off ebay at about a couple of quid each. They've been working fine for over a year now. They run on 3"x2" timber rails and the roof can be moved with one finger. Full details can be found in the obsy build threads.

[fwm891]

Kev - I used a slightly different approach in that I used smaller 50mm wheels but 4 of them on each side running in an inverted 'U' channel. Stayed on so far...

[Astrokev]

My roll off uses 100mm rubber tyred wheels with needle roller bearings. I got mine off ebay at about a couple of quid each. They've been working fine for over a year now. They run on 3"x2" timber rails and the roof can be moved with one finger. Full details can be found in the obsy build threads.

Thanks Gina. Have you seen any flattening at all with your rubber wheels? Some folks have suggested this could be a problem.

[Gina]

No, not in the least - it still rolls very smoothly. Apart from the last couple of inches where it engages the safety pegs to prevent lifting in storms, I can still push it with one finger.

[Astrokev]

No, not in the least - it still rolls very smoothly. Apart from the last couple of inches where it engages the safety pegs to prevent lifting in storms, I can still push it with one finger.

Thanks Gina. That's good to hear and opens up the available choices somewhat.

[midnight_sky_watcher]

Good luck on your build.

[tony]

http://www.ebay.co.uk/itm/Gate-wheel-pulley-wheel-80mm-V-groove-steel-wheel-/321040768189?pt=UK_BOI_Industrial_Supply_Material_Handling_ET&hash=item4abf855cbd

[tony]

good luck with your build kev, you'll probably be done before me i've had no time on it in over a month now.

[Astrokev]

good luck with your build kev, you'll probably be done before me i've had no time on it in over a month now.

Thanks for the link Tony, they look interesting and are less expensive than I thought. Prompted by this I've done a bit of browsing and you can pick up V profile gate wheels for around £6, which I think is very reasonable.

Not sure my build will be finished before yours though. I don't get much time and am still at the design stage. Hoping to "break soil" in the not too distant future though!

[tony]

Thanks for the link Tony, they look interesting and are less expensive than I thought. Prompted by this I've done a bit of browsing and you can pick up V profile gate wheels for around £6, which I think is very reasonable.

Not sure my build will be finished before yours though. I don't get much time and am still at the design stage. Hoping to "break soil" in the not too distant future though!

its work commitments that dont leave much time, 10hr nights/days alternate weeks 6 days a week atm, cant complain there i suppose it pays well, wife works nights alternate weekends too, luckily this weekend shes not working, having to leave mine for a bit, a few other things to do which are taking time but hopefully back on it next weekend. on the bright side though i have my timber in the garage.

on the subject of wheels and track, was thinking of these wheels

http://www.ebay.co.u...=item4abbc4ac24

sold with either a 9mm or 11mm wide groove

then use this as a rail

http://www.aluminium...oduct_info.html

8mm square ali bar, 1mm of play wouldnt of thought would make much difference, save it being tight i suppose. costs more for delivery than the ali itself, £12.49 delivery, the ali is only just over £6

[Gina]

I don't think steel in contact with aluminium is a good idea - the differing metals will encourage corrosion.

[Tinker1947]

I don't think steel in contact with aluminium is a good idea - the differing metals will encourage corrosion.

The Aluminium will start to corrode when in contact with steel, it show up as a white powder........

[malc-c]

The question I have is how do you attach the angle track without the screws getting in the way of the wheels?

Just countersink the holes. If you do it carefully enough you can get the depth right so the screw head fits the countersink just right and the wheels run over them without issue

[tony]

The Aluminium will start to corrode when in contact with steel, it show up as a white powder........

thanks for that, and gina. so steel track then. what about s/s? can get that in 8mm .

[Astrokev]

The Aluminium will start to corrode when in contact with steel, it show up as a white powder........

For square profile gate wheels, would L section mild steel angle iron laid flat work? This would be easy to screw down without the fixings interfering with the wheels, although I wonder if this would put excess strain on the fixings since all the weight would be bearing down along one edge of the angle (if you understand me?).

The other approach which I'm thinking about is to use "inverted" L angle and V profile wheels. This would put more evenly distributed load on the angle, but I think would require the wheels and track to be absolutely parallel to avoid the wheels "riding" up on the track, which may be more difficult to achieve.

With square profile wheels, providing the track was slightly narrower than the groove in the wheels, there should be more room for lateral play which may be easier to construct.

[tony]

For square profile gate wheels, would L section mild steel angle iron laid flat work? This would be easy to screw down without the fixings interfering with the wheels, although I wonder if this would put excess strain on the fixings since all the weight would be bearing down along one edge of the angle (if you understand me?).

The other approach which I'm thinking about is to use "inverted" L angle and V profile wheels. This would put more evenly distributed load on the angle, but I think would require the wheels and track to be absolutely parallel to avoid the wheels "riding" up on the track, which may be more difficult to achieve.

With square profile wheels, providing the track was slightly narrower than the groove in the wheels, there should be more room for lateral play which may be easier to construct.

theres 1mm play, 8mm track and 9mm groove in the wheels

http://www.metals4u.co.uk/Stainless-Steel-Square-Bar/8mm-304-square/82/8699/detail.asp

or

http://www.ironfinials.co.uk/steel_bar_steel_tube.html

suppose steel will corrode with the weather but assuming stainless steel is ok with the steel wheels then theres that one.

[Astrokev]

Hi Tony

That second link seems very reasonably priced . How do you intend to mount the rail - drill and screw directly to your roof beams? With 8mm rod, the screws will have to be quite small gauge. I think mild steel would be easier to work with; stainless is more difficult to drill. Regarding corrosion, if I go for steel track, a coating of grease should keep the rust at bay.

[tony]

Seems a lot of hassle, think i might as well go proper gate track and round grooved wheels.

[malc-c]

Seems a lot of hassle, think i might as well go proper gate track and round grooved wheels.

I opted for the "traditional" screwfix wheels in an ali channel. One of the reasons was this option runs relatively quiet, and wont wake the neighbors up when I close up at 4am

[Astrokev]

I opted for the "traditional" screwfix wheels in an ali channel. One of the reasons was this option runs relatively quiet, and wont wake the neighbors up when I close up at 4am

Yes, the more I think about it, I'm starting to think standard rubber tyred wheels would be simpler (and cheaper). Ali channel is probably quite expensive. I guess the same could be achieved with having the wheels roll on the wooden beam, with a single side board on the outside of each beam to stop the wheels falling off. This approach would allow rain to drain off quite easily, rather than forming a "gutter" which would collect water.

Kevin

[Bizibilder]

That's the system I use - rubber wheels from screwfix on wooden runners with an outside wooden rail to keep things straight. Works well and is almost silent in operation.

[Astrokev]

Having considered lots of options, I think I'm settling on the following design for my rolling roof design.

Gate wheels and rails are superb, but quite costly. The design below (not to scale) should be relatively easy to construct.

The wheels will run on aluminium plate strips, which will be mounted on top of rubber roofing membrane (shown in black) and will be screwed to the wooden beam with countersunk screws, with silicone sealant to seal the screw holes. This should give a robust rolling surface which also protects the wall beam from the elements.

The lateral wheels will be mounted on wooden battens hanging from the roof joists, with a small gap between wheel and ali strip to allow for imprecision in the roof alignment. Rubber membrane will be wrapped around the end of the joists which should protect the wheel assembly.

I'll probably also design in a ply strip underneath the lateral wheels and some brush strip to create a windproof / bug-proof seal, which I haven't shown on the drawing.

I'd be interested in people's thoughts on this design. Are there any areas I could improve?

Thanks

[r3i]

I'd be interested in people's thoughts on this design. Are there any areas I could improve?

Thanks

Perhaps the inclusion of some kind of captive mechanism to help prevent the roof going airborne if there's a strong gust of wind?

[yesyes]

I quite like the captive mechanism that Mike (r3i) has build onto his obsy. I have designed that into mine from the start (I just make the horizontal joist where the wheels run on a bit wider).

Maybe you could design that into yours as well and you don't need to worry anymore about holding the roof down.

http://stargazerslounge.com/topic/168972-yet-another-observatory-build-thread/page__st__60#entry1765469

[yesyes]

heh! same thought... :-)