How I decided on the size:



Some designs I saw specified 1&1/2"x1/4" OR 1"x1" OR 1&1/5"x1/2" sizes.



I figured that the smallest size would be lighter and would be strong enough if I had the slats

"overlap" enough, and I saw at least 3 sets of plans that used 1/4" thick slats, so I used

that size.

As it turns out, the flexibility of the thin slats is really good for portability as it allows the yurt wall to be rolled-up rather than split into sections and layed out flat.

I thnk 5-6mm is OK, but only if your timber is not prone to breaking, and has natural flexibility in it. Other timber batches do require 7-8mm. In all three tents that I've made, I've always used pine, because it's easily available, and cheap, but there are differing qualities, and using the lowest quality pine (once, in my second tent) did result in more damage occuring, more easily, so I prefer the higher grade/s now.

The extra 2mm might not sound like much, but it'll make a big difference while still giving

the flexibility...or you could leave it that thin and use a slightly harder timber than pine

(eg meranti)...pine is probably as soft as it comes, so anything comercially available will

be stronger than pine. If you don't have pine locally, use whayever softwwood it is that your house frames are normally made out of.



What size I ended up using:

I used approx 6mmx35mm (1/4"x1&1/2") cut from 90x35mm pine construction timber.

Using a "thin kerf" saw blade in a standard circular power saw I was able to cut 9 or 10 slats from

each 90x35 length, so I cut up 8 lengths into about 80 slats, and this gave me some spares

to allow for the more than occassional knot in the timber which weakened the slat and/or

caused it to snap. Don't throw out broken slats as these are used around the door where

the slats must be shorter.

The structure is quite flexible with such thin slats ..it's quote strong enough tho, so if you are after a LIGHT and easy to carry wall structure then go for 6mm, a reasonably sized guy (me!) can easily carry my entire wall structure when it's rolled up into one 8' long 300mm across cylinder.

I've seen other designs that said when they rolled their walls up they rolled up to 2' (600mm) across, so either mine is more flexible/lighter or I rolled it tighter, or both.

Length of timber was 8' because the slats are angled at 45 degrees when setup, giving a wall

height of approx 5'6", which is adequate for anyone 'normal' (if you are 6'6" tall u might like

slightly taller walls).

My timber yard is aimed more at the commercial market, and they sell in

3.0,4.8 or 6.0 metre lengths only...which is great, I just bought the 4.8 lengths and asked them to

cut them down the middle (to 2.4m or 8') "so I can transport them easier in my car".



How I cut it:

I mounted the circular saw upside down (with the blade parallel to the wall) onto a "saw table"

which I made up temporarily from a few scraps of timber I had lying around. The table top

needs to be almost twice as long as the timber you are cutting "longwise". The table I jigged up

was about 4 meters long.

I then screwed a "running board" to the top of the 'table', parallel to the saw blade, so that it was 6mm (or your prefered slat width) behind the saw blade.

Remember that the saw itself is actually underneath the table, and has the blade sticking up

through a slot that you sawed in the table just for this purpose!.

Don't use your dining table for this! DANGER: dont ever try this at home! ;-) Using an exposed saw blade like this is a definite danger. If you like your fingers DO NOT go anywhere near the saw while it is running.

In order to switch the saw on/off and keep it on without holding the trigger in all the time, I

plugged it into a powerboard that had built-in switches, and used these to switch on/off, I then

used a "zip-tie" around the handle to keep the trigger "on" permanently.



In order to keep the timber that is being cut hard up against the timber running board( and hence

make sure that the slats are consistent in width - which is important), I added a little swinging

pivot to the table near the saw blade, and hung a heavy weight off the pivot with a piece of thin

rope.

It was arranged such that the strip of timber that made up the pivot pushed up against the

front edge of the timber being cut, and the counter-weight (in my case a large lump of hardwood,

but a house brick or 2 would also do) pulled on one end of the rope with the other end tied to

the pivot.

The overall result is that the weight on the rope pushes the 'pivot' timber, and

that in turn holds the timber being cat hard against the running board. If none of this makes

sense to you, thats OK, don't worry about it, just find a willing volunteer, give them a "push

stick" and charge them with the responsibility of holding/pushing the timber hard against the

running board while you feed it along the length of the timber being cut.

See the picture below if this is all still to much. It really quite simple, it's just hard to describe.



(SIDE NOTE: a "push stick" is a piece of scrap timber at least a metre long (or 2) than anyone

working with a table saw should be using at all times that they are anywhere near the saw. It

is used to push the piece of timber that is being cut, so that you can push it right up to and

through the saw blade without worrying about things like loosing fingers, etc, having your grip

on something slip and 'whoops there goes that hand'. The end of the 'push stick' is sacrificed

to the god of the power-saw as it becomes sliced and diced up...better it than your fingers!)



Calculating the Quantity of slats required:



A number of factors are involved... 1) how many bolt holes (ie overlapping slats) you have in

each slat. 2) how big you want the finished tent to be, and 3) how many roof supports you want to have.



1) number of bolt holes can be between 5 and 10 per slat. I have seen examples of 5,7, 8 and 10.

The person/plans I saw that said they used 5 later said they had modified their plan by adding

intermediate holes, and converted the 5 to a 9 hole. I figured that I'd pick a middle figure

out of 5,8 and 10. I used 8 holes, layed out thus:



first hole : 3"(75mm) from one end (the top)

next 7 holes: 1'(300mm) in from the last

leaving : 9"(225mm) between the last hole and the other end (the bottom)



This gives a "grid" when assembled whose sides are 1' (300mm) in length.



My finished tent is approx 15' diameter. It seems that most designs I could get my hands on a based around a 15" tent (or close to) as it is quite large enough to normally sleep say 6 or 8, and

this makes it perfect for two or three and leave lots of room to spare.



Some maths: lets assume we want a tent of around 15'(4.5m) diameter, and we are using 8 bolt holes separated by one foot into an 8' slat as described above. When the slats are assembled we will also assume that they are angled at 45 degrees. This results in a wall height of around 5'6" with the slats at 45 degrees.

The angle of the roof will mean that the centre of the tent is over 7' tall (more on that later), so if you are more than 5'6" tall, don't worry, youll only have to duck when going thru the door.

If the slats are at 45deg. then they will be forming diamond shapes in the wall grid that are actually completely square. the width of these "squares" across the diagonal (ie horizontal to the ground) is (using pythagoras) square-root of 2, or 1.41' (424mm).

In order to get a tent that is 15'(4.5m) round you need a circumference of 3.14x15' (3.14x4500mm) ie: 47.1' (14.13m). with each 'square' being 1.41'(424mm), that means we need 33.65 of them to go the entire way round the circumference.

Each square takes two slats, so we need 67.3 (must be multiples of 2) rounded to 68 slats for the entire tent. That said, we haven't allowed for the door yet, or taken into consideration how the roof sits on the top of the walls, but you get the idea....next, the doors etc....



If we make the door 2x1.41' or 2.82' (846mm) wide, then it's an nice even figure, and we can

simply reduce the number of required slats by 4 to 64. (the door taking up the space that those

slats would have take up).

Since the roof supports have to have their lower end supported onto a point where the slats

intersect, then we must be able to divide the number of 'squares' around the tent evenly by

the number of roof supports we decide to use.(or suffer un-evenly spaced roof supports - eek!)



When building my yurt, I forgot this next bit of the step, so every time I put the roof onto the walls, the roof suports never quite sit right as I have to put them onto the nearest intersection , which isn't exactly spaced out. Oh well, it still works well, just not quite as neat.



The neat way: Lets say we decide the roof is to have 8 primary supports that hold up the centre ring, and 8 secondary(smaller cross section) supports that are for stopping the canvas sagging, so we end up with 16 supports.



In order to divide the number of roof slats up evenly into the number of wall 'intersections',

we must have either 16,32,48,64 or 80 'squares' around the yurt (counting the door as two for the

sake of the math). Since we figured that we we going to have '33.65' (rounded to 34) squares

(see above), then we were pretty close to the required 32 that we have just said we must use. Of course, you could also change the number of roof supports to match the walls, rather than change the number of wall slats to match the roof supports. Say you've done what I did, and built your walls, then realising that the number of roof supports you cut is wrong, it's easier to cut another roof support or two than it is to change the wall structure...so long as you haven't built your center 'hub' yet, otherwise it's easier to add or remove a few slats from the wall.



So, the decision I made was to have 16 roof supports, meaning 32 'squares' (two of them

are the door), so with 30 actual squares (32 minus two for the door), we should need 60

slats (plus or minus a few to be cut up either side of the door), and have a resulting tent

size of just a smidgen smaller than we originally said.



The final size is 32x1.41' or 45.12'(13536mm) circumference, and 14.37'(4310mm) diameter

if you keep the "diamonds" perfectly square. Just push the walls out a little more, and make

them a couple of inches shorter, and you still have the 15'-16' tent you started with.



Phew!.



SIDE NOTE: other plans I've seen vary the roof supporting structures from 5 to 45, so there is a

lot of variation here. The upper end of the range is most likely for areas that experience

snow, or that are using extremely thin roof supports, or that like the idea/neatness that

comes from having a roof support on the top of every single wall 'intersection' - ie where

two wall slats join at the top hole, the lower end is possibly for those using a very heavy

canvas, or a smaller tent size that doesn't need as much 'support' to stop sagging) My original

planned roof used 8 as I was goinf for maximum portability, minimum weight, but I modified the

roof before I had even finished building the yurt to be 16 as stated above, and this is a much

better result for minimal weight gain - the secondary supports don't really have to hold much

weight at all, just some canvas. It's the primary ones that hold up the ring. Some other plans

don't use two types of roof support, but instead opt for all of them to be load bearing. This

works too, and will probably give you a roof ring that you can do chin-ups from without any

problems. I hang entire wardrobes of garb from mine with no problems.



Drilling the holes into the slats:



Use a drill press, or be VERY careful to make sure you drill straight thru.

Every plan I read said that a drill press was a good idea. I didn't use one, I was just really careful, and mine worked, but if you are "powertool-impaired" like some of my friends (hi Wolfe!) then you must use a drill press, or get one of your non-impaired friends to do it.

Because the timber I'm using is soft (pine) and gives a bit due to how thin it is, I was able

to get away with the holes being up to 3 or 4 mm off center by the time they came out the other

side of the the 90x35 (drilled thru the 90), but I really strongly recommend taking your time

and getting the holes really straight as it makes lining up the bolts so much easier.

Be accurate and consistent in your measurements when marking them onto your timbers before you drill too as this is also really important.



Assembling the walls:

I've seen plans that specified rivetting, tying with cord, cotterpins, and bolts.

Bolts are so much easier then rivets, and so much stronger than cord or cotterpins. Just make sure that you either use self-locking nylon nuts , or deliberately damage the end of the bolt thread after putting the nut on (this stops the nuts coming off in-transit and getting lost).



I just hit the thread end of the bolt with a hammer a bit as it's cheaper than nylon nuts

(go to the hardware store and check the price difference for yourself - if you are on a tight

budget you'll do what I did).

If you are building a yurt/ger then you've obviously seen how the walls are put together so I

wont bore you any more. It's just a case of inserting 300 odd bolts thru the right holes, putting

all the nuts on (no need to tighten them - actually tightening them is very bad!), and then

making sure the nuts won't come off easily after you damage the thread a bit.



The only assembly point that is ESSENTIAL is that all the slats angled one way are *inside* the circle, and all the slats angled the other way are outside the circle, otherwise the frame won't fold-together in a scassor-like fashion.



Like I metioned, my holes were sometimes up to 5 mm off in places, but the timber has plenty of 'flex' in it so I just encouraged it a bit with a hammer where necessary, and made it fit. ;-)

(don't hit the timbers to hard or you'll break the slats before you even start).



Near the doors, the slats must get shorter by one hole at a time, I fiddled with the shape of the

timbers where they joined onto the door frame, just because I wanted a neat finish. Everyone does their doors differently as it depends what you want.

Traditionally (in the 1600's and earlier) the monguls would have just had felt 'flap' doors, not solid timber hinged ones, but I've seen quite a few that go the solid door (and it's popular in mongolia nowdays!) as it makes for a very secure structure, and is pretty cool.



Mine is a extremely simple frame made from (suprise suprise) 90x35mm pine framing timber. Two lengths the height of the finished wall (5'6"), and two of the desired door width (2.82' or 846mm). I made the simplest possible door frame, and the door is a canvas drapery that I hang over the space. I did that because I wanted portability, and a big solid door seemed like a real pain to carry around. To do similar, I suggest using a large timber screw called a coach screw, two in each corner of the door, , and drill a hole through them, and screw them together.



Other options might be :

1) a 'door' that is still canvas/cloth covered, but is actually

made of lattice like the walls, this is portable and secure, I'm sure you could make a lock for

it somehow.

2) on one plan I saw recently on the web (it might be in the URLs listed below, I

don't remember) had a "double" door, by that I mean solid "french" doors. Two

half-width doors with one hung from each side. It's more portable, and still solid. I'll

probably do this way eventually.



