You keep talking about WiFi. More important is a refrig for the beer. Why would anyone want WiFi in a treehouse. I would think this would be a place to escape all that stuff.
G. Ross wrote, on Mon, 29 Sep 2014 20:38:51 -0400:
Good point, but, this *is* the Silicon Valley environ ...
---------------------------------------------- In days of yore I worked as a design engineer for heavy duty steel mill and foundry equipment, but that was then and this is now.
For designs involving steel cable and human safety, the basic safety factor applied was 5.
IOW, 14,000/5 = 2,800 pounds as the basic design limit.
Dynamic loading would apply another 50% derate.
IOW, 2,800*50% = 1,400 pounds for dynamic loads.
Based on the posts I have seen, your group needs some serious help before people get hurt or worse.
Lew Hodgett, PE Retired
I think everyone's offended, now days. And you hurt my feelings by writing that.
. Christopher A. Young Learn about Jesus
Does PRC have more attorneys, or Mexicans?
. Christopher A. Young Learn about Jesus
Sounds like my elementary school lunch room monitor woman. We used to call her Bubbles.
. Christopher A. Young Learn about Jesus
Hmm, well with two separate cables your power requirements are fine, just run them on 24VAC @ 50A (120VAC @ 10A equivalent) and then use step up transformer or AC to DC regulators to power everything in the tree house. No unsightly wires!
John :-#)#
Lew Hodgett wrote, on Mon, 29 Sep 2014 18:29:57 -0700:
Times two cables, which is 5,600 pounds, at least. :)
My last comments - this is not looking so good..
Bending a cable around a support weakens the cable - there is a formula for that:
So that derates the cable strength from 10% to 60% depending on the curve. Note too that they are using wooden standoff/chocks to hold the wire, I hope they chamfered a notch - but in any case the load is not consistent on the tree, rather it is concentrated on only a few of those wooden chocks. This is a derating aspect too.
Looking at picture:
It looks like the cable does a bit of a sharp bend where it leaves the standoff...this is potentially a real problem - kinks are possible. The pinching of the cable at the clamps also derates the cable strength...
Wire Rope is certainly varied in structure. However I do keep seeing the
1:5 load factor (1/5 of rating) in various Wire Rope 101 pamphlets...It does appear that the folks selling wire rope are only too happy to advise in its use - your friends would be advised to show them the proposal for comment before they put too much weight on these wire ropes.
John
You better check it. Wind loads can exceed the dead loads by many times. Wind loads may be the real issue.
?-)
On Mon, 29 Sep 2014 23:20:40 +0000 (UTC), "Danny D." wrote in
Not true. Since you are a volunteer and not an employee, you are complicit.
That's generally considered offensive, racist, and ignorant.
Perhaps they have better manners.
There is one picture of a guy standing right beside the tree. If he is 6' feet tall, then the top of the picture would be about 42 feet.
----------------------------------------------
"Lew Hodgett" wrote:
----------------------------------------------------- What I forgot to include was that the above design loads are for tensile loads.
Bending loads require a further derate.
The reader is left to determine the value from any decent structural engineering text.
And now you know one of the reasons why I'm retired.
Lew Hodgett, PE Retired
Sounds like not much fort, at derate we're going.
VinnyB wrote, on Tue, 30 Sep 2014 06:00:21 -0500:
The neighbor "pays" me, in free soda, although I am complaining about the intolerable working conditions nonetheless!
BTW, today we devised a (potentially ingenious) method to *level* the two cables.
I couldn't snap a picture because we were installing WiFi rooftop radios most of the day and I was using the cell phone for signal strength and interference observations, so the battery had died by the time we got to the treehouse.
However, I'll explain in words, and later snap a picture for you, as to how we devised a "tool" to measure the respective cable sag.
We made an 8-foot long T-Square out of two-by-fours, and we notched the upper outside two ends of the top horizontal bar of the wooden "T" for the cables to go in.
Then on the 8'foot long vertical leg of the huge T-Square, we put a level on the side. We could easily see the 8-foot-long T-Square was "tilted".
It was getting late, so, later this week we will actually climb the big redwood 100 feet away, and pull on one side of the cable or the other, until the 8-foot-long hanging T-Square shows that the vertical leg is level.
At that point, the two cables will be level.
We hope.
Seymore4Head wrote, on Tue, 30 Sep 2014 15:57:42 -0400:
He's about 6'2" or 6'3" tall.
And, those are the *small* redwoods halfway down.
The big redwood tree is another ten or twenty feet below that, downhill, whereas the 100-foot long 10-feet wide suspension bridge will be level.
It's a "home engineering" project, in the Santa Cruz mountains!
Danny D. wrote, on Wed, 01 Oct 2014 11:09:36 +0000:
Sorry it took me so long.
Here's a picture of the method we used to level the two 100 foot cables:
We basically made a ten-foot wide T-square, where we used a level on the vertical bar to measure how level the two cables were.
If they weren't so high off the ground on the very steep slope, we'd just hang a lead weight from the midpoint of each cable, with an even length of rope for each cable - but we preferred to work at the only *flat* part along the entire 100 foot length of the two cables.
It was really difficult working in the trees to pull the cable around as it's both very high up in the air, as you can see by this netting we rigged:
And, the last redwood tree downhill itself is pretty gnarly, as shown here looking up at the same netting but from the safety of the ground:
Danny D. wrote, on Sat, 11 Oct 2014 05:38:07 +0000:
You can see the fencepost digger in that picture above, over to the left.
It wasn't easy, mainly because the California sediments are hard as rock this time of year, and, we were roped to trees so we wouldn't fall down the hill while we were drilling the fencepost hole in the slope:
It was my first fencepost hole in my life, so, I was surprised that the two bags of concrete mix went in dry:
Being on a 45 degree slope, it was impossible to keep the water in the hole, so, we tried containing it with a cut-off bucket - but it didn't work all that well to contain the water:
The second fencepost hole, for the drawbridge-like structure, wasn't as hard to drill as it was on a much (much) flatter portion of the hill where a path crossed under the cables strung between the redwood trees:
The last step of the evening was to stain the boards that will be used for the hundred foot long ten feet wide bridge from the top of the hill to the far redwood tree:
When i have seen that done it didn't work out that well, the concrete never set properly. Sometimes it had to be dug out a few years layer and done normally mixed before placement after removing the mush.
?-)
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