PE - Ger structure, continued :-)

[Corun MacAnndra]

Todric wrote:
>
>>If you put square poles into a square hole, and they fit tightly, then they
>>don't really need to be at an angle.
>
>        I think she meant the roof-pitch angle, Corun.

Actually I don't think she did. You snipped too much. Her actual comment was;

>For the record, my roof poles are square. The ends that go into the roof ring
>are cut at an angle, thus 'locking' them in so they don't twist.
 ^^^^^^^^^^^^^^^^^^^
To me that reads the the poles themselves are cut at an angle, much like
the flat roof poles Alan of Warhaven designed and that I keep referencing.
Of course only Mira can tell us for sure what she meant. Mira?

>        That's because folk don'tunderstand "the iris effect". They place
>their ring blocks radially rather than in parallel pairs, so naturally they
>end up with a ring that will rotate, and is liklier than not to "iris" under
>stress. If the poles are allowed _any_ side-to-side motion, the ring will
>have the same freedom of rotation. QED

I don't understand what you mean here. All roof poles radiate out from the
roof ring and are thus placed radially. And the roof rings that hold the
flat roof poles don't have "blocks" per se. They have openings that hold
one to three flat poles (I've seen many variations on the theme). My roof
rings have always been made from blocks, one per pole, in which I drill a
hole the diamater of the closet pole. Orignally I used 2x4's, but now I use
3x3's. The iris effect you mention comes from a loosely tensioned yurt and
roof poles that fit loosely in a ring which thus allow the ring to swivel
around its circumference, thereby causing the ring to literally twist
itself into the ground.

>> It's an old
>>design as Todric pointed out, and, if done right, can work. But if any roof
>>ring and pole arrangment is done Right<tm> then it shouldn't need the extra
>>supporting ropes tied up near the roof ring to prevent twist because it
>>won't twist. This is the whole thrust of my comments.
>>
>
>        Oh!
>         Why? 
>        I didn't say anything about rectangular poles (ill-fitting or
>otherwise); I wasn't talking about my old "flat-disk & blocks" rings; and I
>wasn't referring to any twisting or "iris" forces. Nothing I make twists or
>rotates that way.

You also weren't talking about round poles either. Since I know you've
always sold the plans for and built the plywood roof rings and flat 1x2
roof pole type yurts it was natural for me to presume you were still using
that technology since you weren't otherwise more clear. I went back into
your original post and nowhere did you state what kind of roof poles or
ring you were using. Since it made no sense that one would need to support
round poles with a cord laced through them, but it did if one were using
the flat pole technology, then that's what I thought you were talking
about. QED.

>        No, the extra cord doesn't in any way prevent "twist"; it has
>nothing to do with "twist" and nothing to do with how snug the fit is for
>any pole. It simply prevents the poles from unplugging from the ring when
>the forces on the wall are grossly uneven.

Again this references the ovaling effect you mention you heard about from
second hand observations. Personally I doubt that this is what actually
happened when the poles in your eyewitness' roof ring came unplugged, but
that's just me. I need to be shown that this will actually happen in a yurt
that is properly set up (i.e. has poles that fit snugly into the ring and
that has a sufficiently tight set of tensioning cords and/or bands). Until
then I will believe that the poles unplugged from vibration and that the
yurt was loosely set up (Nota Bene: This is not a commentary on the
construction, but on the set up. Even the best constructed yurt will fail
if not set up properly).

>        Remember the little pins I suggested that you add to the ends of
>your roof poles? The ones that kept the poles from sliding inward through
>the holes in your ring? 

Actually no I don't. I do however vividly recall the little pins I came up
with to prevent the poles in my first ger from sliding through the ring,
but I don't recall at all that you had anything to do with that idea. When
I discovered one day at that Pennsic that the roof was getting lower and
that there was more roof pole inside the ring than was there when I first
set up, I realized what had happened in my calculations and by next Pennsic
I had drilled holes and glued 1/4 inch pegs into them with just enough
sticking out to seat against the ring. The holes were drilled at an
approximate 60 degree angle to the pole, thus making them sit 90 degrees to
the ground and parallel to the face of the roof ring.

Of course now, as I mentioned above, I use 3x3 blocks and don't need to
drill all the way through these since I can drill a sufficiently deep hole
to seat the poles, and with the girdle cord and belly band I don't worry
about poles popping out from the yurt vibrating in heavy winds. I make 3x3
blocks and can ensure that they are 3x3, unlike store bought 2x4's which
are in fact 1 3/4 x 3 3/4 in size. 

>This cord works as though there were pins on the
>_inside_ of the ring, keeping the poles from _pulling_ (not twisting) out of
>their holes.

But now I think I see what you are getting at and what you have failed to
mention in all your comments about this cord you put on your poles. You're
still building roof rings that are open all the way through and thus have
poles sticking out inside the ring. This is where your cord goes, isn't it?
I will suggest that if you build a solid roof ring and not have the poles
stick through, and that if they fit snugly and you have sufficiently tight
and well placed set of tensioning bands and/or cords around the yurt, your
poles will not unplug from vibration.

I will also suggest that if a yurt is going out of round into oval, then
something is seriously wrong with the way it was set up.

Corun


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