RoR wheel size

[Marke]

Just wanting to get some concensus on what size wheels / castors
for a RoR 3x3.6 . I was originally going to go with v-groove till I got the price :eyepop: just too much . I can get plain 50mm steel castors from local hardware
for a couple dollars each so I am rethinking to go that way and just running
them on angle iron or Al .

Mark

[Terry B]

I just have about 6 castors on each side running in channel steel. Just get reasonably strong ones and use lots of them.

[Marke]

Thanks Terry , how do you find it tracks in the channel ? I know about adding a guide wheel to keep it straight which is what I had thought of doing.

[Terry B]

It works quite well. I also have a guide wheel on the outside of each track. If I deliberately push on one side I can make it jam but as long as I push evenly it runs well.

[DavidTrap]

Best RoR I've seen uses grooved castors running on a track made from upturned angle iron.

DT

[Marke]

I know David except the castors are $45 each ! thats what I had planned until I got the price - x12 I dont think so

[DavidTrap]

The roof I'm thinking of is pretty large and heavy and there's not 12 castors on it.

DT

[Marke]

How big is it and how many castors a side were you planing ? I figure I need at least 5 a side for 3.6m

[Moon]

Was the $45 quote from Richmond?
http://www.richmondau.com/engineering/products/track_wheelv.html
If not, it might be worth giving them a call.
I have 3 on each size, v-groove cast iron castors on upturned angle iron. Rolls very smoothly. There are some pics here (http://deepspaceplace.com/observatory.php)
James

[Marke]

Yes James it was from Richmond unfortunatly compared to plain steel castors at $2.50 each its a big difference . I guess 3 would work but I would feel happier with more.

[pmrid]

I'm guessing that it's my ROR that David is talking about so I'll throw in my choices and reasons.
When I built it, I used standard Bunnings 4" wheels and they ran on a rail. They didn't have bearings in them. The roof is 4 x 5 metres and made of steel with Zincalume roofing so yes, it's heavy.

I originally only put 4 wheels a side in but soon found that this was not enough. I added another 4 a side and it was OK but still sluggish and over time, prone to the wheels becoming a little eccentric and hard to get going.

I re-engineered the roof to run on vertical steel bar rails using castors with bearings. These are relatively small, about 50-60mm OD I guess. I set them in 50x50mm square steel box section with a spring-loaded axle - so that only the bottom 15mm or so actually show below the rail in which they sit. These now run smoothly on their steel flat bar rail. I have 8 a side.

Peter

[Moon]

This might be an important point to consider if you plan to add an electric opener later on - in most cases it's mounted on one side or the other (not in the center of the roof).
BTW I also started off with the bunnings $2.50 special and ended up replacing them.
James

[Marke]

I may look at some better quality castors than the bunnings ones. Its a shame the v-grooves are so expensive but others have managed quite well
with out them . Building the thing will be the easy part, but sourcing all the little bits is a pain - and dont get me started on the door thats my next thing to tackle .

[mswhin63]

I learn't a lesson with my current DIY project, try not to buy stuff from Bunnings if possible source from specialist places unless discounted heavily.

I bought some threaded rod from Bunnings 10mm x 1m cost $approx $8.00. Sound cheap. I went to Coventry Fasteners and bought a higher quality zinc rod for $3.80. Go figure :(

There are some specialist castor places may actually be cheaper, I know they have a much greater range.

[Marke]

Thanks Malcolm I have been spending a lot of time shopping around so far. :)

[DavidTrap]

The observatory I was actually thinking of belongs to Chris (hotspur) up at Blackbutt - sorry Peter. He's posted some photographs of the internals of his observatory before on IIS, so it may be worth a search of the archives.

He bought his from a "Castor Shop" in Brisbane.

DT