When I originally chose the castors, I was going to cover the roof with corrugated plastic roof sheet, but then decided to go for the much more impact-resistant Onduline. But Onduline is *much* heavier than plastic roof sheet! So anyway after replacing a couple of the castors like for like and seeing that these also quickly showed signs of wear, I decided the best course of action was to upgrade the castors/channelling completely. I looked around and found these 50mm castors from Screwfix:
As you can see they're a lot beefier than the old ones, so changing to these should mean that they will hopefully last the lifetime of the observatory. I also bought some wooden lats from B&Q to replace the aluminium channelling which I think was one of the causal factors for the failure of the original castors:
I had to wait several weeks for a weekend of good weather, as I didn't want to run the risk of a sudden downpour on my unprotected 'scope.
So last weekend I enlisted the help of the BADAS Secretary, Terry Devon, and went about dismantling and removing the roll-off roof.
So first the exterior side panels had to come off:
Then the Onduline roof panels, which came off in one big piece, as they were all glued together with roof sealant. Zac took the opportunity for a quick sunbathe before the Onduline came off!:
Once the Onduline was off, Ziggy (who only visits a part-time basis) had a feel of the new pavement over the gravel:
Terry and I then lifted the roof off and put it on the ground. We then turned it over, and we removed all the old castors and replaced them with the shiny new ones.
I drilled holes in the lats so that they could easily be screwed into place to form the new U channels for the castors to run in:
Once these were fitted Terry and I lifted the bare roof back up to check that it rolled OK - and it did :-)
The castors look much more up to the job than the old ones did... :
However with the new castors being so much taller than the old ones (~60mm) it means that there is only a tiny gap between the warm room roof and the obs roof when closed, so that needs to be addressed as I want a bit of an air gap so nothing starts to rot:
Also the motor, limit switches and roof closed/open sensors all need to be re-positioned for the new level of the roof.
