over split-ring locknuts. There's a camp that have a theory that they serve no useful purpose at all ( for the NASA Fastener Design Manual).
BTW, for overhead use, malleable wire rope clips are not recommended; drop forged are ok. For rigging overhead lifts, cable clips aren't allowed at all, but with the above caveat on type they are allowed for static overhead loads.
Are you saying that the tree house will be in the middle of a 125 foot suspension bridge. How much will the tree house weigh when fully loaded and do you have any idea of the forces that may be in the cables?
G. Ross wrote, on Sun, 28 Sep 2014 13:39:26 -0400:
We plan on balancing the load.
Maybe that won't work - maybe it will.
If we need to, the turnbuckle can be added (somehow) as a rube goldberg; but at the moment, the load is supposed to be balanced when we build the bridge hanging from the cables.
I'm relaying all this information to the neighbor as I'm just a helping hand. I jokingly refer to myself as the "union worker" because I make jokes about OSHA getting on their case every time I have to climb one of those ladders!
I do apologize that updates are slow, as I can't snap a picture unless I'm there, and the treehouse is only worked on during the weekends, and I'm not always there to help, but I will try to snap pictures as we progress.
Dunno if I should append all to the same thread, as the way "I" read this newsgroup is that I only look at the threads from the last day or three. Dunno how others look at older threads, 'cuz this could take a few months elapsed time.
I'd suggest it (balance control) will become mandatory and mayest as well design it in from the git-go. W/ as much effort as you're investing, this is a pretty minimal addition.
You also have to consider the geometry of what you are creating. If you are tensioning the cables for very little sag then the forces in the cable can be many time the weight of the tree house. Without knowing exactly what you are creating then I cannot guess. That is why I asked if you had any ideas of the forces in the cable.
I do not know what you are planning upon building. That was why I asked you. If you are talking about the tree houses that we built as kids with a plywood floor and a few boards and a tar paper roof then only a couple of hundred pounds. If you are talking about some of the multi story creations that I have seen on TV then many tons.
Dan Coby wrote, on Sun, 28 Sep 2014 20:32:48 -0700:
We "tensioned" the cables, by hand.
What we literally did was put a broomstick through the 60 pound wooden spool of 250 feet of 3/8" steel cable and we mounted that on two chairs about 15 feet downhill of a big pine tree.
Then we went uphill to that pine tree at a point about 15 feet off the ground and then back to the chairs with the spool of wire.
At that point, we tied a rope to the end of the wire, and we walked the wire downhill a little less than about 100 feet to a big redwood.
At that redwood, we climbed up to the same height as the pine (which, since it's downhill, is about 40 or so feet up in the air) and we pulled the rope with the wire cable attached.
Then we pulled the rope which pulled the cable back up the hill back to the point on the path 15 feet below the pine, where we pulled it tight by hand, and then clamped the 8 clamps on.
Then, we simply slid the cable around the big redwood and slid it around the pine, until the cable clamps were symmetric around the pine, as shown in the last set of pictures.
I won't mention the fact that we accidentally crossed the cables because we went around the big redwood the wrong way, as that's embarrassing to mention. Nor will I mention how many times we got hung up in the branches between trees, necessitating mid-air precarious surgery on the trees.
Given all that, I wouldn't call the tension all that tight. You can see the sag in the photos. Maybe it sags, oh, I don't know, about 5 to 10 feet maybe?
I think we're talking just a plywood box, with a deck. I should mention that there will be anchors on the two little redwoods, so, the treehouse won't actually be floating on all sides. The bridge *will* be floating though. It should be fun once it's done and wired for Internet. It has a great view once you're up in the redwoods.
Have you allowed for a windstorm where the trees may be moving in opposite directions to each other?
Temperature affects the length of the wire rope, have you allowed for maximum and minimum temperatures?
You want some sort of shock absorption built in too. Old antennas used porcelain blocks for joining cables, the porcelain would shatter under unexpected loads giving the cables a chunk of extra slack to avoid their collapse by stretching beyond limits.
May I suggest you find an engineer to look over your design? I'm not one, but can think of a few ways for this to go wrong already including the clamps failing etc.
Suspension bridges are close to what you are building - read up on the design criteria for these. Seat of the pants design may give you another Tacoma bridge...
John Robertson wrote, on Mon, 29 Sep 2014 09:54:57 -0700:
Only that each cable supports 14,000 pounds! :)
Hmmmmmm.... The cables don't "give" a little when you walk on the bridge that would be hanging below it?
The neighbors are all owners of companies and people with graduate degrees, so, they *are* engineers (of all types). The one having the most fun with the design is the retired carrier fighter pilot. :)
Yes. I'm told the catenary will turn into a parabola once we hang the bridge off of it. Since the bridge starts uphill about 15 feet above the trail, it will be fun to just step onto the bridge, at the level of the trail, and then walk "downhill" level but going higher and higher above the steeply sloping ground, to get to the two smaller redwoods in the middle of the span.
At that point, we will be in the "treehouse" which will have a deck and WiFi and a great open view of the mountains.
Then, if we want, we can walk further to the *big* redwood, which will have sleeping quarters (hammocks and cargo nets) for the nights we'll spend there.
It should be fun, once done, and I'll try to keep you guys informed; but I personally am not designing or building it; I'm just the free help (we all have Spanish nicknames when we do free labor. I'm "Rodruigo", and my wife's nom-de-labor is "Marisol", for example).
I keep threatening that I'm gonna call OSHA on them if I fall or if they don't provide cold soda (the free soda has been warm, to date).
Speaking of doublechecking my work ... notice this picture:
formatting link
It's how I *finally* learned how to hook up the ascender so that when I climb the precarious ladders, the ascender just slides *up* the rope, with effortless ease, but, it *locks* into place instantly if/when I fall.
You won't notice, but, there are *two* mistakes that I didn't make in
*that* picture, but which I had made when I *first* hooked up:
The amber carabiner placement is critical:
It goes AROUND the rope (not outside the rope).
It goes on the TOP (not the bottom of the ascender).
I learned both those tidbits the hard but gentle way.
At first, I had hooked the carabiner on the bottom of the ascender, thinking that the top hole was already *busy* with the rope, but, what happened when I tried climbing up the ladder was that the ascender, which is clipped to my waist by a locking carabiner, flipped upside down as I went up the ladder.
Then, I tried hooking the amber carabiner to the top hole, which prevented the flip, but which actually hindered the rope movement if it was outside the rope.
So then I hooked the amber carabiner *around* the rope, and then everything worked smoothly, as it should.
As I climb the ladder, the ascender just slips on the rope, causing no problems whatsoever; but the moment I descend, it locks instantly in place.
Trial and error ... but it works nicely now that I know how to set it up.
I had forwarded this thread to the owner of the treehouse in the redwoods, who replied with the following ...
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People worry too much.
I simply design for 10 times the expected load, and pay the premium. Trying to finely engineer the solution where torque and special fasteners are important is a way to save money, and I'd rather spend the money and not waste my time. I've never seen a malleable cable clamp. Drop forged ones are cheap, and I use more than normal anyway, not because I think they are needed, but because they help keep the cable from slipping out of place on the wood block spacers.
The reason for keeping the U-bolt on the dead end of the cable is because the saddle has a lot more surface area, and thus does not reduce the strength of the cable as much as the U-bolt does. But they make dual-saddle cable clamps, for those who don't use the over-engineering approach I do.
Each cable can support 7 tons, so the total weight of treehouse and occupants can be 14 tons. (Although there will be other supports besides the cable -- one end will rest on the ground, and another end will be anchored to the tree, and there may be other support cables used just to make installation and leveling easier.)
If half of the weight is treehouse and the other half is people, we have 7 tons of treehouse possible (although the actual treehouse will probably weigh less than 1.4 tons fully furnished), and 7 tons of people (70 people, if they are all 200 pounds). I doubt we will ever have 70 people in the treehouse -- they'd be shoulder-to-shoulder.
No, that's pretty much correct (if rather dated). "Oriental" literally means somebody from "the East". Asia is usually defined as "East of the Urals". Both are somewhat vague terms with meanings that have changed over the centuries, but Wikipedia says the're pretty much the equivalent:
The Orient means the East. It is a traditional designation for anything that belongs to the Eastern world or the Middle East (aka Near East) or the Far East, in relation to Europe. In English, it is largely a metonym for, and coterminous with, the Continent of Asia.
Calling a Mexican a Spaniard is like calling somebody from the US "English" or "British". Rather than being insulted, I think people are just going to be puzzled over where you've been for the last 250 years.
Either, both, maybe neither (it probably depends on the crowd). Regardless of whether it's insulting, it's incorrect.
I hear that about over engineering stuff. When I was getting ready to pour the floor for my shop I calculated the concrete thickness for the various machines and then though about what happens if I move a machine and then what happens if I buy a heavier machine or one with a smaller footprint and so on. Then I realized how pointless this was in my situation, So I had the concrete poured to 7 inch minimum thickness, had fiber put in the concrete, and I put rebar and wire mesh in place before the pour. It's a good thing too because I later bought a lathe that covers 10 square feet with the base and sits on 4
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