Slow Geodesic Dome build

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  • Hi All



    I have actually started work on building my Geodesic Dome greenhouse for the allotment. I have been talking about it for years and waiting until I had enough money to buy all the materials etc but to be honest I am never going to get it built if I wait until everything is in place sso I have decided to just start building it anyway.



    When it is finished it will look like this





    We have built the base this weekend. The base is quite complicated. There are 15 base boards made up of three different types. Each of the base boards need to have a 12º angle at each end and along its top edge. 5 of the board also have to slope to the right and 5 to the left.



    A couple of days ago I bought the wood and cut all the boards to length with the right angles on the ends. Then I set about cutting the tapers with the 12º angle along the top edge. I did this on the table saw by setting the blade at a 12º angle and setting the depth so it just cut through the board. I then used another board on top of the one being cut, offset by 32mm to give me the correct taper (I hope)





    All the boards cut





    I cleared the ground of grass and weeds and started fitting the base boards yesterday. Using a stake in the centre of the dome as a datum point for both level and radius ir was not too difficult to assemble the base although I will need to tweak it a little when I have an extra pair of hands





    Now we need to start making the jigs for making the 103 triangles that make up thee dome. We will make triangles as and when we can afford the materials but I hope to have the dome made by thee end of the summer.



    I will keep you posted


    paul

  • That looks a great project, Paul!


    Do you have to get any planning permission for that size of greenhouse? We're restricted to 8' x 8' x 7' high up here, whether it's a shed or a greenhouse, although you can have one of each if you want.


    I looked at geodesic buildings back in the 1970's, when they first got popular in the States, but never had the opportunity to get involved in building one. So yours should be an interesting project to follow; you'll have to give us some rough indication of the costs involved. Sure looks a little complicated from the cutting and assembly point of view.


    Best wishes with it, will watch progress with great interest.

  • Maybe, maybe not. It depends how you look at it. For me, a major benefit is I can source all the materials locally and buy them in small amounts as and when I can afford them. The longest piece of wood in the construction -not counting the door frame- is under a metre so I will be able to get a lot of the materials from the scrap pile at many building sites etc. Also the plastic cover is done in small sections so I do not have to outlay a massive chunk of money at one time for a polytunnel cover. i can buy off cuts from a local supplier for less money. They will contact me whenever they have pieces that are too small to sell. I estimate that if I bought all new timber it would cost about £500 to build and will give me 5 to 7 years of service before the plastic needs replacing. So that is £2 a week over 5 years. When I do need to replace the cover I can do it in small sections with off cuts of plastic again and I only need to replace the sections that need doing instead of the whole cover if it is a tunnel.


    I also want to attract as much attention to what I am doing as possible and I think the dome is going to attract a lot of attention. No one is going to get excited about a poly tunnel but everyone who sees or hears about the dome is very excited by it so that is a massive benefit.


    paul

  • To inspire others or to offer your services building one for them?


    Both really. I do want to start producing these for people but also I am passionate about changing peoples attitudes towards growing their own food. I do do things differently than most people and I am not saying that my way is any better than other ways of growing food but what I am saying is that there are different ways of doing things and you shouldn't just do things because that is the way it has always been done without questioning why.


    I want to introduce the general growing public to things like permaculture, aquaponics and intensive gardening techniques and the dome is going to draw people in as they are intrigued by it.


    paul

  • I am trying to do a little bit towards this each day or at least several times a week and as it is nice weather I thought I would make a start of the templates for the triangles.



    There a two types of triangle that need to be made. One type makes pentagons and the other type makes hexagons. I need to make 30 pentagon triangles and 69 hexagon triangles so an accurate jig is essential.



    You start by cutting one of each of the triangles from plywood. Then you clamp a piece of 2 by 1 along each edge basically making a finished triangle as it will go in the dome. Once you are happy with your shape you hen fix anther triangle of 2 by 1 inside your first triangle and screw and glue this inner triangle to the plywood. this is your jig.



    I have cut the plywood but I am getting the first bundle of wood tomorrow so will try and get the jigs done then





    paul

  • Things are moving on now and it all seems a little less daunting.



    I was expecting it to take about 10 minutes to make a triangle but I can do them a lot quicker than that and that was the first ones I have built and I haven't really got a system going yet.



    It took me about 30 minutes to build 6 triangles and then assemble them into a hexagon panel.



    This is fantastic as I was thinking it was going to take weeks to build a dome but if there is the two of us and we have a system I reckon we could do a dome from start to finish in a few days and a day installing.



    Anyway. I am pleased with the potential speed at which I could build a dome if I had all the materials at hand. I have run out of screws now so have to knock it on the head but I am keeping a note of everything I need so when I am building future domes I will know I have all the materials and supplies on hand before we start.



    I am getting excited now





    paul

  • A smart man would buy all the materials. Cut all the components, stack them on a pallet and send them off for pressure treating. It would cost about £30 for the pallet full to be treated. They come back wetter with the pressure treatment but will last 15 years without further timber care. If you think that you will get paint or any other type of wood preserver into the tiny joints, you will miss a good 60% of joints internally. This wood will rot from within in side of 5 years. So it's not the plastic that will be the problem, more the soundness of the dome structure and individual joints.

  • I would love to buy all the materials at once but I have been waiting for years to have the money to build this bloody dome and I think the only way I am going to do it is to just do it and buy the materials as and when i can afford it.


    I am using tanalised timber which I understand had been pressure treated so I am hoping it is going to outlast the plastic cover. plus the fact that the dome is made up of many small components means I can replace any that are showing signs of deterioration.


    I know a lot of 'smart men' who spend their whole life planning and never doing


    paul

  • Cool looks like you are one of them dar smart men! Tantalised is as good as it gets, although they do wave warranty if it's cut after treatment. But more chance of preserve penetration any way. You can repaint tanalith on the joints as you fix them. Sorry for not asking about the timber quality before I dropped my size. 10's in 😀

  • Not dangerous, just not good for putting on gardens/in compost or as pet bedding etc. what else you could use chemicalised sawdust for I have no idea!


    Thinking about it, the treated sawdust if collected clean and dry'ish. Would make good insulation if used as a cavity filler, sheds, greenhouse cold frames, garden, it won't be rotten in 20 years.

  • Sounds good, but by cutting it you have made it less waterproof surely?

    it is pressure treated. The timber is loaded into a sealed chamber. Water, sap etc is sucked out of the wood when the chamber is subjected to a vacum. Then preservative is impregnated into the timber under pressure. Theory is it will get into the heart of the timber. Cutting may expose any internal area not deeply treated. They do suggest treating any cuts.

  • The preservation of timber/wood (tanalising) used to be carried out using a mixture of salts of copper sulphate, potassium dichromate and arsenic pentoxide.



    The timber was pressure injected with the preservation liquid in large pressure cylinders, after which it was stacked in the yard while still wet with preservation chemicals. It was not sold till completely dry to reduce contamination.



    This was fine in dry conditions, but in the wet the chemicals could leach out, and the arsenic be transferred to the hands simply from touching the timber.



    Children in particular are prone to use their hands for eating without washing them first, and can get arsenic poisoning as a result. Food plants grown near tanalised decking can accumulate sufficient chromium to cause symptoms of heavy metal poisoning in anyone eating the produce.



    A family in the Antipodes (Australasia) used offcuts of tanalised timber on their barbecue. The cooked meat killed their dog and resulted in prolonged hospitalisation of the entire family.



    Recommendations include avoiding drilling or sawing or use a dustmask if this is unavoidable. Wash thoroughly after touching tanalised timber, and avoid use where people are likely to come into direct contact with the treated timber.



    Arsenic has been banned for tanalising in Europe since 2006, although the current tanalising process has been found to be less effective without the arsenic content. The replacement process - Tanalised E - uses copper and triazole biocides - an organic anti fungal treatment commonly used to protect food crops.


    FROM............http://www.recycledplasticbuil…o.uk/warnings-concerning-tanalis



    NEVER burn any kind of tanalised timber such as old painted timber or boards, which contain formaldehyde resins (i.e. most plywoods, chipboard, and mdf). Tanalised E may be burned in approved industrial incinerators only, but should not be burned in open fires or home wood burners.

  • As you have seen in the previous post I have completed the first of the Hexagon panels so the next step was to complete a Pentagon panel so I could be sure they would go together before forging on and making the rest of the triangles.
    There are only 6 Pentagon panels to make and now I know they work and everything fits together and my two chop saws are set to the Pentagon angles I will press on over the next week or so and make all of the pent triangles.
    Here is a picture of the two jigs needed for building this dome. The tall one is for Hex triangles, the other is for Pent triangles.





    Making the triangles is simple once you have the templates built and checked for accuracy. You start by cutting the correct angles on one end of each of the struts. then you clamp the struts to the template and screw the struts to each other and saw the projecting ends off.
    I will add a photo of this later.
    As I am finishing each triangle and before I take it off the template I mark the apex of the triangle as this makes it fool proof when assembling the panels.
    Here is a picture of the finished Hex and Pent panels before putting them together to test their fit.





    You wouldn’t normally make the panels up like this before covering in plastic but as this is the first dome I have built I wanted to make sure everything lined up and the two panels fitted together.
    Here is a picture of the Hex and Pent panels fitted together.





    To give you an idea of the hight of the finished dome there is another Hex panel to go below the Hex panel in the above picture. The picture above does illustrate the curvature nicely.
    So now I have to get stuck in to making all the rest of the triangles and covering them with plastic.
    Ultimately there will be a detailed step by step article on the Geodesic Dome Page of this Blog
    More soon
    paul

  • Might have found a solution to the tanalised saw dust problem. our local saw mill will tanalise the timber after I have milled the angles and sanded the wood smooth so no more deadly dust.


    It is going to end up costing about £35 + VAT per dome


    Too late for this dome but future domes will be less toxic to build plus I can just add tanalising as a optional extra which the customer will pay for.


    Paul

  • I'm assuming untreated timber will be cheaper than the pre-tantalised wood you are using now so you'll recoup some of the £35? Have you figured that out yet? Would be interested to know .... :)