*
Wednesday 10th 52F, dull grey but dry and mild.
I spent several hours this morning trying to make the shutters operate smoothly. Or even move at all!
I checked and adjusted the base ring level using the 360° laser level. Then tried various height settings for the lower, drawer slides. All without improvement. I have cut notches in all the ribs to ensure clearance from the base ring and slides.
One shutter rib is bent where it has warped in the lower third. So I left a long clamp on it over lunch to see if that helps. The ribs were no longer parallel with a considerable variation in spacing. [4cm] I can screw a length of timber on the back of the rib to hold it straight if needed. This is a dead spot in the dome so it won't get in the way just there.
If the slit ribs aren't straight then the shutter ribs cannot lie evenly against them. This would tend to tilt the shutter to the left or right. Which night affect free movement. Or it might prevent the shutters from closing. The slides must be level, parallel to each other and not under tension from structural distortion. Leveling is easy.
Checking whether they are parallel with a 2m difference in vertical height is another matter. Perhaps I should drop two plumb lines. One from each end of the zenith board. To which the upper slides are firmly attached on the back. I could use a length of wood [or a long strip of metal] as a combined, plumb bob, weight. Then I could use the laser rangefinder. To check the distances from each end of the lower, drawer slide support. Why has it taken me so long to think of this?
15.00 It started raining so I had to close the shutters. They actually closed together nicely. Which they wouldn't do before I fitted the clamp to straighten the slit rib. Interesting. I shall have to delve further. The long clamp can stay on overnight. I may be able to flatten the warped rib by laminating it with thicker plywood.
*
No comments:
Post a Comment