Geodome Project

 Progress has been slow but steady off-late thanks to non-deliveries of dowels from the UK (brexit) and a certain lack of focus from pandemic blues, for want of a better term. However, the current status is All sticks or struts  manufactured.  Polythene unit cells being assembled Site has been attacked with weedkiller and soil turned. Concrete blocks sourced. Numerous seeds are being cultivated in trays. Polythene Cover Cells So....after a couple of previous trials working with the original 'triangle' base units I quickly realised I could save a lot of time / effort and tape by making larger base cells. Whilst in theory it is possible to construct single cells from the core haxagons and pentagons I decided to use 1/2 heaxagon units due to difficulties in handling, lousy weather outside and therefore strict limitations on indoor area available to stretch out polythene film. The core thing about the hexagon patterns is that they are not real pentagons due to the raised cent...

 Tuesday 16th Feb 2021 the polythene material for the geodome cover arrives.  Delivered by Liam of Allens of Allenbridge   by car. 13 m x 8m = 104 sq metres of high quality UV stabilised polythene. 9 rolls of 20m x 0.1m repair tape Material is light but very strong and pretty much as expected. The rolls of tape are made in France and I'm assured stronger than the polythene it is designed to join. The tape is semi-transparent and also UV stabilised and hopefully will not stick out too much as the tape joins are coincedent with the spars (sticks) of the geodome structure.  In the next couple of days some initial trial will be run to assess the flexibility of the taped joints....which I think will determine the maximum size of the geodome cover sections. Update on the 'sticks' Well, I grew old and impatient waiting for the larger dowel diameters ordered a few weeks ago. Another victim of Brexit, the stick were apparently stuck in customs. Soooo....I cancelled the o...

 Preparation of the ground to receive the dome is something I can start to consider given the fact I am waiting for some more dowel rods and the weather is slowly beginning too improve. This is a good approximation to the geodome structure....plan view. Some numbers to consider Perimeter for 5.2m diameter dome is 16.33m A standard concrete block 44cm x 22.15cm x 10cm 16.33 / 0.44 ~ 36 blocks ~ 10 degrees offset to form circle. (360 degrees) Photoshop Estimate Total no of blocks  36 circular plinth and 40 for perimeter wall. 

 Door Placement and Calculations Door will be formed a base heaxagon made up of the perimeter of 6 'B' s and the spokes of 6 'C' s. Doorway aperture ~ 1.82cm tall / 1.05cm wide I think this is a reasonable compromise between structural strength degradation, difficulty and comfort....ie some of us will have to stoop slightly to make the job considerably easier to complete. My primary school trigonometry suggests the 'hexagon centre height' is of the order of 20cm. So what does it look like and do the 'hubs' have enough play to form a rectangle in the centre of the would be hexagon.    The standard raised centre hexagon hub is removed on the right hand side and the central sticks re-aligned to form the rectanglular would-be door-frame ~ 1.8m tall.  So , it appears that all I have to do is make a couple of poles to form the doorframe plus a couple of short lateral posts to connect these poles 1/2 way up to the 1st horizontal row of sticks above ground level...

 Cover Enquiry Have discussed requirements with Polytunnels covering company located in County Cork. Recommended use of very strong UV proof Tape to join polythene triangles, just shy of 2 inches wide and 20 € per metre. This method is likely to be much stronger, faster and reproducible than the plastic welding method I had im mind up to this point, but Liam from Allens, Allenbridge advised that the tape is stronger than the polythene itself. So , how many joints are there. 165 sticks in construction So for this 5.2m diameter dome what does the cumulative lengths of the sticks come out as? Well using the calculator supplied by buildwithhubs.co.uk (download excel file from company) The number of sticks for a 5.2m diameter gedome and lengths is as follows.... A   sticks (short)   81.9cm     quantity 30 B   sticks (med)    96.2cm     quantity 55 C   sticks (long)    98.4cm     quan...

 Sanity Test Assembly Prior to continuing 'mass' production of the 'sticks' it seemed a good idea to assemble a hub or two to check that there were not gotchas in the process so far. I selected the topmost pentagon of the design....5 triangles of 2 short sticks (A) and 1 medium (B) were used. 5 'A' and 5 'B' sticks + kit Attach the Ball Joints to the 'sticks' Press the Ball Joint into the 'Hub' Complete all of the 'Hub' Connections and lock with washer, bolt and  winged nut. 5 satellite Hubs to form triangles complete the uppermost pentagon of the Geodome. There is plenty of freedom in the Hubs which will reduce as you tighthen the locking plates (washers) using the winged nut and bolt.  No Issues were seen as yet and I need to reread the Design Advisory notes as they recommend a max stick diameter of 3.4cm and from my version above....no such limitation comes into play. Looking at their publicity shot its possible that if the sti...

  Physical construction of bamboo. This results in the appearance of a solid core if your rod cut lies on a node. These are usually thin enough to be drilled out to reveal the natural diameter of the bamboo. Various dimensions and shapes OK, due to the construction of bamboo the plugging of the ends of the rods you cut is not so easy. The above shows a typical variation of what each rod end will present to be filled by a dowel trimmed to size. As you can see the sidewalls can be thin (2-3mm). While this is still mechanically very strong...especially under longitudinal forces...you can see that you cant just drill out irregular ends to form easily plugged circles. This means you need to have a lot of dowel diameters to hand and trim them to the irregularities of the bamboo. My Set up Gorilla Tape to wrap round ends of rods to protect against splitting. Wood Glue to secure dowel in bamboo rod. A variety of dowel diameters A sharp craft knife for scoring the inner rods. Hand-drill for...

The Hubs The hub kit arrived after a few days and was roughly the volume of 2 shoeboxes. This is the 3V frequency option and can be used for all sizes....ie angles stay the same only the appropriate stick lengths change. (see calculator ) Core Hub Module llooks like this. (smaller than you'd think) Ball joint clips into the hexagonal / pentagonal connector and secured by screw, washer and wing nut combo. The ball joint is attached to your stick of choice via a screw that extends 3.2cm into same to end up coincedent with the flat of the ball joint arm. Takes a little force to clip the ball into the socket and a little play in the angle of the ball wrt the joint but generally feels good.  61 hubs in all for this dome and 360 ball joints to connect everything up......A lotta lotta work ...so need to get it right first time. (some trials required re ball to stick connectivity). The Poles The bamboo poles followed a few days later. Ordering is done in 4m lengths which you can have deliv...