Dome build: Base ring progress at last.

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The image shows the base ring leaning against the 5m, 16' ladder. I was trying to capture what little sunshine there was @ 48F to help the glue along. A near frost overnight is forecast with rain all day tomorrow. What to do with the ring? Lay it back down, with a tarp over it, I suppose. Luckily I can still stagger around while carrying the ring and cross braces. Though that may no longer be true when the second layer of 15mm is added.

It should obvious, even to me, that consuming a heavy sheet of plywood, by cutting it into arcs, does not make it any lighter. I am just happy I didn't choose to cut the arcs from 18mm [3/4"] ply!

I doubt I'd have the physical strength to move the completed dome carefully on the wheels even if I survived beyond the tipping point. There would be another movement of several feet before the sliding ladder fully bridged the octagon. Best to forget such heavy lifting!

I have bolted the boat winch to a 2x4 to have something solid to fix to the pier or the octagon. I simply don't have the strength to lift the ring bodily by a rope even with the help of the sloping ladders.

Thursday: Wet. Very wet.

Friday: A much more promising day but much cooler. It has now occurred to me that adding another layer of 15mm ply to the existing base ring will almost double its weight. It might be best to lift the original ring onto the supporting wheels on the octagon. Then add a similar completed ring on top. That leaves the problem of applying the hardboard ring underneath. It looks as if I shall have to build the second ring first, complete with the hardboard layer. Then take the original ring up last to plonk it on top.

Or, complete the second ring and attach the first on top of that. Then lift the whole lot using the winch as planned. This would make for a much stiffer but heavier ring to lift into place. I can lay 2x4s across the octagon to receive the ring without risking the wheels catching on the ring.

These timbers must be able to be removed easily with the weight of the full ring resting on top of them. Which suggests blocks between the wheels rather than full lengths of 2x4 right across the octagon. The height of the wheels is almost 8" so that needs 2 lengths of 2x4 set on edge and joined with perforated roofing plates. That is a potentially unstable set up so I may use blocks of 2x8s joined side by side as 4x8s. Only the gap between the pier and far side of the octagon needs continuous support for sliding the ring into place.

The tarpaulin is full of water where it rested on the ring overnight. I placed a couple of ladders across to keep the tarpaulin off the ring. That was a waste of time. It still looks like an ice-covered, round, paddling pool after yesterday's rain followed by frost!

The white tarpaulin drying in rare sunshine. I tried hanging it from the top like a curtain but it was mostly in shade.

I don't hold out much hope for the glue reaching full strength. Which leaves me wondering what to do about doubling the ring thickness. I can use screws but neither glue nor construction adhesive is likely to be useful at near freezing temperatures.

I had a trial lift using the winch to raise the original base ring, with its cross braces, up the ladder. The inclined lift went well enough, but It was quite a struggle getting the ring over the protruding wheels. 8" high blocks and well spaced, full octagon width, timber runners would definitely be required for anything heavier. I may leave the ring up there for the moment. No point in it lying on the wet lawn gathering ice and water.

I finished marking and cutting the slanting joints of the second ring and added it to the first up on top of the wheels. Lots of screws will have to do until it is warm enough for wood glue. Which could be another six months under normal weather conditions. Ideally, I need to invert the ring for a smoother track over the diagonal butt joints. Or insert the hardboard arcs underneath the doubled ring to smooth out the lap joints. Though this is not the best option.

The underside of the ring is accessible in the centers of the octagon sides should I wish to drive screws upwards to hold the hardboard. I moved one 'steering' wheel outwards slightly and that was enough to free the ring from tight spots. It rolls very easily now.

Saturday: A wet and windy morning makes any progress unlikely today. The sky to the north is black! I have no idea how to tarpaulin the ring if we are to have gales. Large and heavy puddles in a covering tarp on top of the ring would be very unhelpful. Any form of central support off the pier would have to be very well padded to avoid piercing the 'tent.' Lightweight tarpaulins are very fragile and barely waterproof from new.

Should I invest in a heavy tarp to place directly over the dome skeleton? The weight could be a serious problem when trying to work underneath it. I would like to continue building the dome using screws rather than glue. Then, when the temperature allows it, I can remove the screws to separate the components and squeeze some glue into the joints.

Perhaps I should build the complete dome skeleton down on the ground. Then cut and mark the trapezium panels to fit. The dome could then be properly rebuilt, with glue, as a proven 'kit of parts' up on the octagon in the warmth of spring.

A big, red, big bale loader keeps passing me on the local roads as if to emphasize the wisdom of a single lift of the completed dome. I presume it belongs to a contractor who fills vast farm buildings with big hay bales right up to the roof. Or it could be a local farmer who own one and hires himself out. They are increasingly popular for lifting roofing and building materials on construction sites.

I did some online research and these telescopic loaders can manage huge lifts [several 1000s of kg] to great heights. They certainly wouldn't break a sweat lifting a modest plywood dome just a bare few meters. The machines can be hired by the day for a manageable sum. This may the way forwards. Because I can't really see the point of taking risks, messing about up there in the wind, snow and rain if it all has to be taken apart again just to glue it back together.

Click on any image for an enlargement.

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