4.02.2022 Not a full dome.

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Friday 4th heavy overcast, windy and wet.

 This morning I was able to fit both pairs of shelf brackets between the slit ribs and base ring.

The smaller shelf brackets went outside the ribs. The larger inside. Both just cleared the stud [threaded rod.] The shutters could still open and close fully without hitting the brackets. I also propped up the spherical triangle. To check clearances from the shutter. The shutters were fine.

There is a problem at the bottom of this triangle. Where it sits just above the base ring. The rain runs down the triangle and straight onto to base ring. The skirt, which will be needed to fill the midriff gap, may have to be flared outwards. To throw the rain clear. I need the base ring to be dry for my friction drive.

 11.00. It started raining. So I closed up the shutters and tidied away my tools. It was still raining at the end of the day!

 The moulded gutter is obviously helping to reinforce the doorway. As well as directing the rain off the doorway and off to the side. A sturdy, arched, steel tube was supplied with the dome. This was intended to further stiffen the open doorway. By being bolted to the gutter when the dome was used as an animal rearing shelter. Frisky calves might easily bump into the overhanging edge of the doorway. So the arched tube was a very useful belt and braces support for the moulded gutter. 

 The tube and gutter also provided stiffness at the open doorway when the dome was lifted.  Strong lifting "handles" were supplied for bolting to the dome at the upper segment seams. These "handles" were intended to be lifted by a tractor. The dome would be lifted and carried clear. To allow easier cleaning up of the soiled bedding inside the domed, calf shelter.  Once the ground was cleaned the dome could be replaced by the tractor's front fork lift, using slings.

 All very clever, but the designers hadn't bargained on my cutting a huge rectangle out of the roof segment. The observation slit was a vital but still risky modification to the sturdy fiberglass dome. 

 The slit ribs and zenith board are helping to spread the loads into the fiberglass dome. Though probably not as well as the original and complete roof segment. I have attached lots of angle brackets between the cut edge of the dome and the slit ribs. I also fiberglassed the joint inside and out. Both for weather proofing and reinforcement. I backed up the GRP with silicone sealant at the joint.

 Unless the triangular doorway patches can be made structural there is always a risk of the slit opening out during lifting. The base ring is also helping [however slightly] to stop the outer corners of the original, arched doorway from spreading apart. The laminated plywood joints of the base ring may come apart under heavy, tangential loads.

 I can't use the entire, arched tube permanently. Because it would obstruct the open, observation slit. Though I could cut the tube away later where it crosses the slit.  Then bolt it, as intended, to the curves above the triangular patches. The triangles would then be trimmed to fit and bolted to the inside of the steel tube. Thereby increasing their own structural contribution. Though the triangles still need to be connected strongly to the base ring to have any effect.

 I quite like this idea. The entire, galvanized, arched tube could remain in place until after the big lift. The image [right] shows how the tube softens the hard appearance of the gutter by filling in its deep shadow. That is a major, cosmetic plus.

 I would have to cut slightly oversized, round holes in the slit ribs. Then thread the arched tube through while it is almost horizontal. The arched tube can then be rotated downwards. So that the curved "legs" are lowered to fit the dome's original, arched doorway. Finish off by bolting it to the gutter. The gutter works incredibly well at directing rainwater away from the sides of the shutters. This tells me to keep it. Regardless of any other considerations.[Mostly cosmetic.]

 Then all I have to do is train myself not to walk into the arched tube as I access the dome though the open slit. I shall probably hang hi-visibility tapes. AND, cover the tube with layers of pipe insulation as a back up. My head is a magnet for any obstruction! 

 There is no need for permanent ties across the slit for the big lift. It would be easy enough to fit several 12mm studs [threaded rods] between the slit ribs. With nuts and large, load-spreading washers both inside and outside to fix the ribs firmly apart. That would certainly stabilize the slit ribs during the lift. All contributions to structural integrity of the dome, during the lift, are greatly appreciated. Only a matter of minutes to remove the studs afterwards.

 

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