Gina's Observatory

[pritc]

Ordered them plus a couple of spares for good measure

Also heard from B&Q who gave me the phone number of their suppliers. Phoned them and delivery is booked for Monday. So things are progressing

Gina,

I am too late.....

I have eight of these (brand new):

Rubber Tyres Fixed 100mm Pack of 4 | Screwfix.com

I purchased these for my Obs/warm room build,but then changed my mind and went to 50mm......

Wayne

[Astrokev]

Approaching the magic 1000 posts. Go Gina, go!!

Good look with the delivery on Monday. Looking forward to seeing some serious action soon via your webcam!

[laser_jock99]

Yes, that's a good point. I've been wondering about buying some rubber tyred wheels instead of the plain nylon ones. The 8 nylon ones only cost a few quid - cheap and cheerful but I'm having second thoughts. The wheels will be protected from harmful UV rays so I can't see any problem with rubber tyres. And as you say, smooth and quiet

For hard wheels, 80mm is rather small. Larger, rubber tyred wheels would run quite happily on wood I think and with a rather heavy roof, would seem better generally.

I'm running on fourteen 50mm rubber wheels in aluminium tracks. Despite the enormous weight (150kg) of the roof its surprisingly smooth to move. I'm putting that down to the large number of individual wheels used and the great care I went to to make sure they were all at the same height (ie all on the track at the same time).

If the roof's heavy don't skimp on the number of wheels!

[Gina]

Gina,

I am too late.....

I have eight of these (brand new):

Rubber Tyres Fixed 100mm Pack of 4 | Screwfix.com

I purchased these for my Obs/warm room build,but then changed my mind and went to 50mm......

Wayne

That's a shame They were expensive ones too, weren't they

[Gina]

Approaching the magic 1000 posts. Go Gina, go!!

going... going...

Good look with the delivery on Monday. Looking forward to seeing some serious action soon via your webcam!

Thank you Weather forecast doesn't look good... Very much looking forward to making progress too

[Gina]

I'm running on fourteen 50mm rubber wheels in aluminium tracks. Despite the enormous weight (150kg) of the roof its surprisingly smooth to move. I'm putting that down to the large number of individual wheels used and the great care I went to to make sure they were all at the same height (ie all on the track at the same time).

Yes, getting them to carry an equal share of the weight is important. I think I'll make up a jig to make sure I drill my holes (for the axles) all at the same level.

If the roof's heavy don't skimp on the number of wheels!

The ones I'm getting will carry 70Kg so 8 of them will carry 560Kg - over half a tonne - if the weight is distributed evenly. When I've built my roll-off I'll weigh it. I've bought 2 spare wheels so I could increase the number if needed, but I can't see the ROR being that heavy. It'll be heavier one side than the other so I'll allow for that in the weighing (I'll weigh each corner).

[laser_jock99]

Yes, getting them to carry an equal share of the weight is important. I think I'll make up a jig to make sure I drill my holes (for the axles) all at the same level.

The ones I'm getting will carry 70Kg so 8 of them will carry 560Kg - over half a tonne - if the weight is distributed evenly. When I've built my roll-off I'll weigh it. I've bought 2 spare wheels so I could increase the number if needed, but I can't see the ROR being that heavy. It'll be heavier one side than the other so I'll allow for that in the weighing (I'll weigh each corner).

The weight rating of the wheels wasn't my main consideration- it's the bearing friction on each axle that will make the roof slide easily (or not). I think it's better to have a larger number of small wheels than a small number of larger wheels- if you see what I mean. Weight wise each of my wheels carries only 10kg (even though each is rated at 50kg static load). Just to be sure the axles were well sprayed with PTFE lubricant before assembly and PTFE thrust bearing washer fitted between the wooden frame and each wheel. I'm fairly sure they're moving as freely as they can under load.

Using a jig to drill bolt holes all at the same position is what I did. I also used a pillar drill to get the hole angle spot on.

My biggest mistake (so far) in the entire build was not allowing for the roof to sag slightly under it's own weight. Make sure you allow a little extra clearance when setting the roof gap! I ended up using a car jack to raise the enough so I could re-drill all the holes to lower all 14 wheels (thus raising the running height) by 1/4". Be warned!

[Freff]

I'm running on fourteen 50mm rubber wheels in aluminium tracks. Despite the enormous weight (150kg) of the roof its surprisingly smooth to move. I'm putting that down to the large number of individual wheels used and the great care I went to to make sure they were all at the same height (ie all on the track at the same time).

If the roof's heavy don't skimp on the number of wheels!

laser_jock99 what are the dimensions for the moveable part of your roof please.

[laser_jock99]

laser_jock99 what are the dimensions for the moveable part of your roof please.

The sliding roof is 4x4m over a 3.3x3.3m building. I have allowed a fairly large overhang due the amount of rain we get here. I'm just hoping the overhang doesn't catch too much wind.....

[Gina]

WOW that's a BIG roof! No wonder you used lots of rollers.

[Freff]

The sliding roof is 4x4m over a 3.3x3.3m building. I have allowed a fairly large overhang due the amount of rain we get here. I'm just hoping the overhang doesn't catch too much wind.....

Many thanks for that.

Mine is 4.5m x 3.0m and I'm planning on running it on 16 x 50mm framed wheels. The roof is double skinned construction with 5 x sheets of 11mm OSB and 10 x .6 mm profiled steel sheets.

I think the steel sheets was calculated at about 120kg + the OSB and stud framing. I will do a more accurate calculation tomorrow when I get the weight of the timber, but the castors in total are rated at 11 cwt so I should be ok.

[Gina]

The weight rating of the wheels wasn't my main consideration- it's the bearing friction on each axle that will make the roof slide easily (or not). I think it's better to have a larger number of small wheels than a small number of larger wheels- if you see what I mean. Weight wise each of my wheels carries only 10kg (even though each is rated at 50kg static load). Just to be sure the axles were well sprayed with PTFE lubricant before assembly and PTFE thrust bearing washer fitted between the wooden frame and each wheel. I'm fairly sure they're moving as freely as they can under load.

The wheels I'm going to use have roller bearings so there shouldn't be much turning resistance. Lighter loading will also reduce rolling resistance. Incidentally, I was told that larger wheels have a lower rolling resistance that small ones. Reducing the tyre width also reduces rolling resistance. This is why racing bicycles have large, narrow wheels/tyres.

Using a jig to drill bolt holes all at the same position is what I did. I also used a pillar drill to get the hole angle spot on.

Yes, I have a pillar drill too. I shall have to move it off the present bench and out into the main area of our big shed to give enough room to manoever these rather long lengths of timber.

My biggest mistake (so far) in the entire build was not allowing for the roof to sag slightly under it's own weight. Make sure you allow a little extra clearance when setting the roof gap! I ended up using a car jack to raise the enough so I could re-drill all the holes to lower all 14 wheels (thus raising the running height) by 1/4". Be warned!

Yes, I'm allowing 5-10mm for sag and general tolerances. But I take your point about the roof sagging a bit - thanks for that

[laser_jock99]

Yes, I'm allowing 5-10mm for sag and general tolerances. But I take your point about the roof sagging a bit - thanks for that

It ran perfectly okay until I got up onto the roof to finish nailing down the roofing sheets- I guess my 14st weight moving around up there didn't help!

[pritc]

That's a shame They were expensive ones too, weren't they

I only paid £20 for the 8

Bargain!!!

Wayne

[malc-c]

It's not so much how much weight each wheel is rated, it's spreading the load over a larger surface area. The more wheels the smoother the movement will be, and less ware on the wheels

[Gina]

It's not so much how much weight each wheel is rated, it's spreading the load over a larger surface area. The more wheels the smoother the movement will be, and less ware on the wheels

Yes, agreed, and for a given number of wheels, the larger they are the larger the surface area. And rubber tyred wheels spread the load more than hard nylon ones.

But for easy running, you can't beat hard wheels on hard track. eg. we have a narrow gauge tramway (railway) we use for moving heavy bales of feedstuffs about. We also buy boiler fuel (anthracite nuts) by the tonne and keep it on a wagon. With the iron wheels on iron track it's quite easy to push a wagon loaded with a tonne weight along the track by hand. You can't do that with rubber tyres.

Having said that I'm still going for rubber tyred wheels as I think they'll be better for running on softwood. I can always buy some ali later if I find any problem with the wood. With wooden guide rails, it would only need flat strip, unless the wooden guide rails prove a problem. There are other possibilities too but I'm not really expecting any problems.

[Gina]

I only paid £20 for the 8

Bargain!!!

Wayne

That's miles better than the £30 for 4 that Screwfix are quoting ATM

[Gina]

Another post bolted onto the appropriate beam. SE corner post this time. May get the NE corner post on today if the weather holds - be back on it in a few minutes

[Gina]

I reckon I can put up all four posts before Monday. Two fixed (south side) and two clamped in place ready for drilling the holes and putting the bolts in, so far. A drizzle shower ATM but should be alright after lunch (which I'm about to dish up). I have carefully measured up and checked for being square so the posts should be alright.

[Gina]

Rain stops play! Still, I did get one more post fixed (NW) and one hole in the other. And still two days before the bulk of the timber arrives, and full steam ahead!!

[Freff]

Glad you are making some progress Gina. My posts have been looking like that for a fortnight.

I bought a 6.5m x 5.25m Tarp last week, £30 from Screwfix. I have a very strong feeling I'm going to need it during the build, and you can bet it will be during a vulnerable time.

We are in for a big blow over the next few days apparently, so I have just made sure all is secure.

[Freff]

Just noticed I've become a Proto Star, (500 posts). Watch out Gina here I come.

[Gina]

Glad you are making some progress Gina. My posts have been looking like that for a fortnight.

Yes, I just felt I had to do something! Not doing anything has been getting me down. Still at least I've been able to get on with some of the jobs around the house and grounds. I've a feeling I shall be suffering from a "one track mind" once the timber arrives

I bought a 6.5m x 5.25m Tarp last week, £30 from Screwfix. I have a very strong feeling I'm going to need it during the build, and you can bet it will be during a vulnerable time.

I think that's the one I've got - bought it months ago.

We are in for a big blow over the next few days apparently, so I have just made sure all is secure.

Yes, I know, same here - we're not very far apart, as the crow flies. Your weather is generally much the same as ours.

Just noticed I've become a Proto Star, (500 posts). Watch out Gina here I come.

Congratulations

[Astrokev]

Just checked your webcam for the first time in a while. Good to see some vertical construction starting to happen, though your weather looks pretty lousy today.

Kevin

[JamesF]

Oooh, it looks even more horrible than it is here

James