Which rollers for roof of roll off roff obsy

[Gina]

I decided to measure up and I found the 100mm diameter wheels had a 20mm diameter half circle groove - 22mm wheel width.  the 120mm wheels had a 17mm diameter half circle groove with 20mm wheel width.  Since the 120mm wheels exactly fit the track, that is also 17mm rather than the specified 20mm.  Naughty, naughty, FH Brundle

The timbers of my ROR carriages are 47mm apart (made from 22mm wide x 95mm high timbers) and I have several 47mm square offcuts so I'll have no problem making blocks to take the wheel frames.

[mapstar]

In industry we normally use one side of the track with grooved wheels and the other side completely flat

You don't get any pinching due mis alignment or due to expansion/contraction not as though wood does that much. But you definitely don't need grooves both sides

[Gina]

That's interesting - thank you

I'll replace the (heavier) south side track and wheels first and try without any sideways guiding on the lighter north side and see how it goes.  I'm not looking for extra work

[Zakalwe]

In industry we normally use one side of the track with grooved wheels and the other side completely flat

You don't get any pinching due mis alignment or due to expansion/contraction not as though wood does that much. But you definitely don't need grooves both sides

There's a fair bit of give in a wooden roof, so it shouldn't bind. When installing the tracks, just fix them at one end. Then carefully roll the roof back and it will align the tracks. Mark the track position and the screw it down.

[Tinker1947]

There will be expansion and contraction with wood quite a bit going from dry to wet but only across the grain not along the grain how much will depend on the size and type of wood, me i would go either with the flat track one side or a groove and the wheels on one side float on the axle,  a small roof such as i have would work with grooves both side but its that light i just slide it along the wood with no wheels to worry about....

[Zakalwe]

There will be expansion and contraction with wood quite a bit going from dry to wet but only across the grain not along the grain how much will depend on the size and type of wood, me i would go either with the flat track one side or a groove and the wheels on one side float on the axle,  a small roof such as i have would work with grooves both side but its that light i just slide it along the wood with no wheels to worry about....

I guess that it will depend on the size and weight. I can't say that I have noticed it on my 7'x7' roof.