Grytpype
Well-known
I'm afraid I may be suffering from a brain-cell deficit (nothing new there!). I've done this job before, and I think I may have had the same dilemma, but I can't remember how I resolved it.
Would I be right in thinking that I should start shutter tensioning with all three springs at zero tension with the curtains in the un-cocked position, and the ribbons fully wound on to their pulleys, so that all the springs are tensioned by the same number of turns?
If I'm reading them correctly, the available instructions seem to be suggesting that you start with the ribbons fully extended, which by my reckoning would mean over 3 turns of tension on the first curtain spring before the ribbons start to tension. This doesn't seem right to me.
Steve.
Would I be right in thinking that I should start shutter tensioning with all three springs at zero tension with the curtains in the un-cocked position, and the ribbons fully wound on to their pulleys, so that all the springs are tensioned by the same number of turns?
If I'm reading them correctly, the available instructions seem to be suggesting that you start with the ribbons fully extended, which by my reckoning would mean over 3 turns of tension on the first curtain spring before the ribbons start to tension. This doesn't seem right to me.
Steve.
Highway 61
Revisited
But it is the right thing to do. If you give the ribbons some length clearance (by winding the ribbons on their pulleys before you start to tension the drum roller spring) the shutter won't work.
Grytpype
Well-known
Admittedly it does seem to be the way Maizenberg prescribes. Both ZorkiKat and Russ Pinchbeck link to Rick Oleson's notes. It's taken me a long time to figure them out, but if I am reading them right, he is leaving the 1st curtain roller tensioned, then giving the ribbon pulleys 15 turns (!) of pre-tension before attaching the ribbons. Even when they are taken-up on the pulleys, this would certainly give more turns of tension on the ribbons than the centre roller.
Mr Scherer says you should not need more than "five turns after the tape is fully taken up onto the rollers" so that could perhaps mean starting with ribbons slack.
EDIT: After a bit more research I reckon you must be right, as usual! My way would make assembly a bit more complicated, so I'm sure someone would have mentioned it explicitly.