Update on the treehouse bridge in the redwoods of the Santa Cruz mountains

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On Mon, 16 Feb 2015 11:19:58 -0800, Oren wrote:

Drill a big hole through it, and put a stainless bar through the hole. Voila! Attachment pins!
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DecadentLinuxUserNumeroUno wrote, on Mon, 16 Feb 2015 19:24:43 +0000:

Right now, the two 16-foot boards to the side of the tree are unattached at the tree (they're screwed into the floating bridge only).
https://c1.staticflickr.com/9/8566/16519997026_ee37d554c5_c.jpg
At the moment, the bridge is wholly supported by the cables and, at the low end, by the posts we first cemented into the ground, when we started this project in the untrampled woods.
It is time for those attachment pins you speak of though...
What we are thinking is that they sell these $100 treehouse attachment bolts, designed specifically for trees (but they're expensive since we'd use probably use four or six of them overall). http://www.treehousesupplies.com/Treehouse_Bolts_s/41.htm
We can't find anything larger than one-inch wide bolts at our local Home Depot, so, we have to order our bolts online, at any measure.
We're debating right now the feasibility of 1 inch or 2 inch bolts, which are about twenty bucks each, versus the treehouse attachment bolts which are five times as expensive. http://treehouseparts.mybigcommerce.com/9-pirch-yellow-zinc-plate-certified-r-32-36-hardness/
So, that's our next question. What kind of bolts make the most sense, keeping cost in the equation (if cost were no object, the treehouse bolts would do quite well).
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Danny D. wrote:

I don't know what kind of bolt you will use, but here is my experience with bolts in a living tree: I fastened some wooden squirrel feeders to trees using lag bolts and washers. In a year the tree grew AROUND the bolt, pulling it through the plank of the feeder. I learned to put a spring between the bolt head and the washer to allow for this.
A threaded SS bar through the tree might be a better option, making it longer than needed so you could back off the nut as the tree grows. Of course you would want a jam nut so that it would not back off by itself.
--
 GW Ross 

 I am a mental tourist. My mind 
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On Mon, 16 Feb 2015 20:24:59 +0000, Danny D. wrote:

Just order the stainless bar stock and have your local auto machine shop of chopper shop cut threads onto the ends.
Get square bar stock if you want to keep it from rotating.
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DecadentLinuxUserNumeroUno wrote, on Tue, 17 Feb 2015 00:30:01 +0000:

Good suggestion!
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On 2/16/2015 3:24 PM, Danny D. wrote:

Are these bolts going to support the weight of the bridge? That seems a bit awkward with the long length of the board. Does the support board run under the bridge to be supported at the other end?
I think rather than drilling into the tree, I would make use of the various branches and wrap a line around the tree trunk like a lasso somewhat higher up than the walkway. The branches will keep it from sliding down the tree without being tight. Drop the line to the walkway or even pass it under and back up on the other side to the same or another tree.
--

Rick

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rickman wrote, on Tue, 17 Feb 2015 20:17:21 -0500:

The bridge is already supported. It's supported by a 3/8-inch suspension cable on both sides. The bolts are simply for redundancy, and, because the treehouse, when built, will add additional weight, even if/when the cable is suspended for the treehouse itself.

We haven't decided what to do with the branches yet.
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On 2/17/2015 7:17 PM, rickman wrote:

Redwood branches tend to die off and fall out from time to time. Not all but here and there. Some are 4-6" in diameter. Consider that but end coming down on you, your car, your shop. One punched through my shop roof and kept out the rain with all of the green junk on top.
I had to cut it off on top and on the bottom - punch out the disk and replace the roof boarding. Glad it was in the shop.
Martin - relocated from my 100 or so tall tree home site.
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Martin Eastburn wrote, on Wed, 18 Feb 2015 23:26:19 -0600:

Some of those redwood branches are as thick as trees, so that's a valid concern. We may need to reinforce the roof, against them falling on it.
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Danny D. wrote:

A dozen years ago we owned a lot (around 4 acres) with many large trees. One huge oak had a horizontal limb about 2 feet in diameter and I dreamed of putting up a spiral stair and a platform on the limb, just for fun. We wound up selling the lot instead of building a house on it, and I went by to look at it a last time and the limb had fallen off and was lying on the ground.
--
 GW Ross 

 My wife has a slight impediment in 
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On Mon, 16 Feb 2015 11:55:31 -0800, Oren wrote:

You should get a less weak grip of the facts.
A one inch hole drilled through the center meat of a Redwood? Hardly. The stainless bar finishes the task. The tree would have no problem growing around the bar, and even if it did not, it would not weaken the tree ANY significant amount.
If the tree could take a 30 ton tornado force before, now it can only take a 29.8 ton force.
Pretty much negligible, is the point.
You'd break the gear you hang on the pins before you'd break the pins or the tree.
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On Mon, 16 Feb 2015 11:55:31 -0800, Oren wrote:

Pine and Redwood are two entirely different trees.
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Oren wrote, on Mon, 16 Feb 2015 11:19:58 -0800:

Oren, ever since kooties and large feet, I've learned that when you say the huckleberries are ripe, the huckleberries are ripe.
I should have taken a picture of it, but, the dog stays mostly on the other side of the fence, not even close to the bridge anymore.
Certainly he doesn't venture out on the bridge. Some day, I'll snap a picture if he does though.
For you, my friend.
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Oren wrote, on Mon, 16 Feb 2015 12:54:30 -0800:

:)
Interestingly, that dog is fantastically protective!
When the mountain lion came by, and we didn't know it, he was barking and yelping like crazy and growling, which is not his normal nature. It was only later, when one of the animals got killed, during the storm, where the dog was locked inside, that we had realized what he was making all that commotion about.
So, now, the dog stays outside, with the rest of the animals, to protect them, even during the storms (which may have abated until next winter, by now).
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Oren wrote, on Mon, 16 Feb 2015 13:33:25 -0800:

There's a funny thing about mountain lions.
They can easily bring down a full-sized buck, so, a puny human "should" be easy prey. Given that they're experienced hunters, I doubt the human would have much time to see the mountain lion that gets him.
Given that, the mountain lion should "win" against a puny human, particularly with the claws and teeth of the mountain lion wrapped around a puny human's head, neck, and throat.
So, given that, why aren't there far more mountain lion attacks than statistics show?
Clearly, where I hike alone (almost daily), mountain lions abound. We have dead deer, dead goats and sheep, and even videos of a mountain lion dragging a buck taken by a dash cam on our winding road.
The enigma is that there aren't really a whole lot of documented attacks on humans. Sure, humans aren't their standard fare; but how do "they" know that?
I'm not worried, but, I do hike in these here hills almost every day, and, I haven't yet "seen" a mountain lion (although I've seen plenty of dead deer).
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The reason is that humans ganged up on and killed critters that dared to take a human. Over the last say 50,000 years, this enduring bit of Darwinist pressure had a big effect. Five or six people with spears are quite capable of killing a lion.
Joe Gwinn
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I've encountered mountain lions (aka cougar, puma) in both the Santa Teresa foothills and the Marin headlands. They're sized similar to a medium sized dog (24" to 36" at the shoulders, 65 to 180 pounds depending on gender and age).
The lions mainly hunt from dusk to dawn, which is one reason that human-lion encounters are rare. The lions are also not interested in humans as prey.
http://mountainlion.org/FAQfrequentlyaskedquestions.asp
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On Fri, 20 Feb 2015 20:01:51 GMT, snipped-for-privacy@slp53.sl.home (Scott Lurndal) wrote:

I encountered one in my back yard. Awakened by the dog barking very strangely, I stuck my head out the arcadia door to encounter mountain lion with my dog standing on top of his dog house shaking like crazy ;-)
Mountain lion took off like a bullet.          ...Jim Thompson
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Roy wrote, on Mon, 16 Feb 2015 11:47:50 -0800:

Thanks for your well wishing. It is one of a kind, so, we're learning as we go. In the end, it will be pretty neat though, don't you think?
It a 10-foot wide suspension bridge, which starts at ground level on a path in the redwoods about a thousand feet (or so) from the nearest anything, and then goes for about 70 feet to a large second-growth redwood, where the deck expands to 16 feet wide.
Sitting on the wide decking, about 40 feet above the ground, will be a two story treehouse, with a bathroom, kitchen, electricity, gas heating, and WiFi Internet (which is something we're experts at by now, given that we all maintain our own radio antennas).
We're thinking of suspending the treehouse with 1/2 inch cable wrapped from the big tree to the two smaller trees cradling the bridge at about the half-way point that you see to the right in this picture.
https://c4.staticflickr.com/8/7284/16358527150_f314ed76cd_b.jpg
So, that way, the treehouse and the suspension bridge would be, in effect, supported separately (or we might make the support mutual and redundant). We're also thinking of adding downward hanging support cables, again from the smaller redwoods to the decking, to add redundancy once the treehouse weight goes up.
One problem we have been having is we have had to constantly adjust the tilt and leveling of the bridge, as weight was added to the end. We ended up buying a dozen cable winches, which are what is holding the bridge up now, one of which can be seen in the left in this photo below.
https://c4.staticflickr.com/8/7414/16358528340_99ca7a421f_c.jpg
We also may erect a few more nets so that we can walk out to the neighboring trees. In fact, if you look closely, you can see two different nets in the picture above. One is to the top left of the picture, and the other is in the center right, in the big redwood tree itself, where someone spent months sleeping in and writing a book, many years ago (his net is still there, 40 feet up in the tree; but we would replace it as it's not safe to use probably, being fifty years old).
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On 2/16/2015 3:42 PM, Danny D. wrote:

Redundant would be good. Bridges without redundant support fall down, e.g. the one in Minnesota--see e.g. http://www.nytimes.com/2008/01/15/washington/15bridge.html .
We're also thinking of adding downward

You can't wrap the cables round the trunks, or you'll kill the trees in a few years. Nice big eye bolts are the ticket, I expect, provided you don't put any torque on them (i.e. you have to drill the pilot hole in the direction of the pull). The tree can easily grow around them, unlike wraparound cables. The problem with wood fasteners is that they aren't load rated, unlike machine bolts.

Sure beats turnbuckles.
I think George Dyson probably published construction details of his famous tree house.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
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