8.11.2021 Slit rib brackets.

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Monday 8th overcast with drizzle. 

I shortened the same shutter rib but the shutter is still stuck. The base boards or drawer slides need to be adjusted to support the shutters properly.

A trip into town provided a load of sturdy angle brackets to reinforce the slit rib junctions. They will each need to be bent slightly inwards to match the dome's internal radius. 

I also bought all their stock of [30] 10mmx18mm rubber washers. To provide weather proofing of the new bolt heads. There is an ongoing problem of sourcing enough rubber washers. They never have more than 6 bags [of 6 washers each] on display. Their website claims lots of stock, in each outlet, but the staff flatly refuse to fetch more from their storage area. Denying that they have any further stock.

There  was a dark overcast and drizzle after lunch. So I worked on the new brackets. I drilled out one of the 8mm holes to 10mm ready for the bolts. I followed up with a countersink to remove the sharp edges. I shall use multiple wood screws driven into the slit ribs.

I chose these angle brackets deliberately for their stiffness, breadth and length. The large, combined, surface area will help to reinforce the junction between the ribs and dome. The spacing of the hole from the 90° bend, will push the bolts well away from the ribs. Reducing the risk of the slit edge tearing out under heavy loads. Most likely to occur during the big lift. I didn't dare rely on the adhesion of the added fiberglass alone. The fiberglass protects the bead of silicone sealer I used on the joint.

I have 20 brackets. Enough to space them at 20cm centers. The same bolt spacing as the dome segment, overlap joints. Hopefully for a uniform appearance. The resulting rows of domed headed bolts give a "steam punk" appearance of riveted iron constructions from yesteryear. One that I do not find offensive. Once the dome is lifted high the bolt heads will probably shrink into insignificance. 

The large [22mm] domed heads will be compressed onto rubber washers. Which will make it impossible for the bolts to tear out through the GRP itself. The multiples of bolts will help to spread the loads evenly throughout the dome's structure.

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