Thread: New observatory
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Old 09-09-2020, 06:50 PM
xelasnave's Avatar
Gravity does not Suck

xelasnave is offline
Join Date: Mar 2005
Location: Tabulam
Posts: 15,439
Originally Posted by Merlin66 View Post
Re cable drives for the roof.
I haven't fitted a motor to mine (yet!) but just pull to open, pull to close.

The ends of the "cable" are fixed to the centre of the moving roof, one at either end.
The cable then goes over two pulleys mounted on the observatory wall and looped downwards.
Pulling one direction moves the roof back and pulling the other side of the loop "pushes" the roof back into place.
I was going to wrap the "loop" around a winch drum to power the set-up....
I can give you a quick sketch of the cable arrangement.
(My roof is 3 x 3 mtr)
Hi Ken
I could not sort out the cable such that it could fix to the centre of the roof easily so I went for two winches one on either side.

I wanted to go for around the drum system like a yacht winch but you need extrodinary tension and I could not achieve such even with additional springs..

No matter what I did I could not make the cable wrapped around the drum work with steel cable. I then tried sash cord to get traction and although it sortta worked the cord turned over on itself..I gave it much time but finally went for just dragging the roof via the winches with cable fixed on and winding onto the drum and moving the pulling point by having a pulley and a hook that I relocate...that works very well...two winches each capable of 2000 lbs...I have dedicated a 120 amp battery for the winches and a 120 watt solar panel...I am making an emergency block and takle more for amusement really and because I just love blocks and takle but if the battery should fail etc I have a block and tackle in place ... plus I plan to have a bench and will use it to move mounts to the bench for work...I can lift them now but one needs to be prepared in case one gets old.

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