Turnbuckles

[trumpets3u]

Looking over the sight there isn't much on this. On the Sky Stream sight on towers they have a 70' tower with 5/16 cable that is rated at 9800lb and 5/8 turnbuckles that's rated at 3500 lb, would you not want your turnbuckles to be rated close to what the cable is? I'm working on a 80' tower and would like a little more in sight on this.

                      Thanks Brian

[Ronnn]

While I don't have a definitive answer, a possibility is that the cable is stronger than it needs to be. Was the turnbuckle offered in a package w/the cable?  Your comment on lack of info on towers caught my attention.

[ now someone will post 8 links to tower threads ] but my question is about the COST of towers in general and their support systems you mention. It's such a crucial element in having or not having a wind turbine. I'd sure like to know more.

 I will see if I can locate the sky stream site and gleen some info on the cost of things tower related. I know things will be priced differently in different parts of the country.  But it would be helpful to know more about it.

Ron

[freejuice]

The cable I have bought ( 1/4 inch)if not mistaken is rated at 6000 lbs.

 However they say the working load limit is 1200 lbs.

You probably are dealing with the same situation.

I'm sure the cable mfg's had to post some kind of working load limit v. breaking limit because a lot of people nowadays carry a lawyer in their pocket like a pistol and are quick to pull it out too!

 All the best,

 Gavin

[trumpets3u]

What I'm looking for is, I'm building a 80' tower of 4" sec 40 pipe with a 10' turbine on it what size turnbuckle would I need? People here say to use a larger cable for the top 5/16 - 3/8 and 1/4 cable for the lower part of the tower. I don't want to under build this, as it is my concrete bases are 3'x3' by 4' deep to get below frost level, I would rather send a little more now that alot later.

                            Thanks Brian

[ghurd]

"I would rather send a little more now that alot later."

Me Too!

On that note, given the cost of everything else, it is quite economical to go overboard on the turn buckles and cable size.

I figured it out once for a smaller tower using prices from the local excuse for a surplus store.  Seems like going a step larger for everything guy-wire related was only $18 difference, but I imagine everything except the cable was of Chinese origin.

In the big picture I doubt it increases the cost 1% to go up a step.

Just my take on it.

G-

[halfcrazy]

On my 80 ft tilt up I used 3 inch pipe soon to be replaced with 4 inch as it is real cheap and I want to build a 12 footer. my bottom guys are 1/4 in and my top 2 sets are 5/16 I used all 1/2 in turnbuckles and while I have no worries about them I would go to 5/8 and I will be changing mine to 5/8 when I build my new tower. Most of my figures have been looked at by my Brother in Law who is a civil or structural engineer I forget which but he was happy with the stuff I used.

[wooferhound]

you would want to put a wire loop around the turnbuckle anyway

as a safety in case the turnbuckle breaks or something

[halfcrazy]

Good point Wooferhound I did not mention that but I have them on mine it also keeps the turnbuckles from vibrating loose.

[trumpets3u]

Thanks for the info, that's what I needed to know.

                      Brian

[Ronnn]

Hi, just curious what price can you get the four inch for. An is it 12 ga. or shd 40?  Would you still feel good about a ten footer on a 60' tower of three inch schd. 40 pipe with cable and turnbuckles up to the task, as in the up sizing you suggest?

I can get some four inch schd 40 for 5 bux a foot but it is in 37' sections. I'm choking on the idea of handling that stuff. But I'd only have one joint in the tower besides the hinge. What to people here think of the threaded joints on three inch schd 40 pipe? The guy at the steel place laughed when I told him someone here said they were weak. I forget who that was but I did see it in a post here. Threaded joints are not an option on the schd 40  4" pipe sections they are just cut off at the ends.

 Lastly, back on the 4" pipe subject, besides a butt joint weld where the two sections join what else would you do if anything, to reinforce this joint in order to feel good about standing this thing up in the wind with a 10 footer on it.

I'm leaning towards 3" shcd. 40.  I can probably get it in 21' joints and it would be easier for me to work with with out help. What is the experience of others here? Oh, the last reason I like the shorter 3" pipe idea  is I can haul it my self w/o renting a goose neck trailer. Money is a consideration here. I don't want to scrimp in the wrong places but I need to save where I can.

Ron

[trumpets3u]

I paid $40.00 per 30' 4" sec 40. At the joint I will be siding 3 1/2" sec. 40 inside the 4" sec 40. The 4" sec 40 is 4.03 internal and the 3 1/2' is 4.0 external. If you read half crazy post he has a 10 footer on 3" sec 40.

                       Brian

[halfcrazy]

Yep I have a 10 foot machine on a 80 ft tilt up tower it is made of 3 in sch 40 pipe. sleaved with 2 1/2 in pipe and welded.

 ((((((ABSOLUTELY DO NOT USE THREADED CONNECTIONS LET ME REPEAT DO NOT USE THREADED CONNECTIONS.)))))

 The threads are cut into the pipe at least half way and maybe not centered either it is sure failure waiting to happen. If you cant weld and do a decent job hire a welder for half a day it will be money well spent.

[DanB]

In all the towers I've seen, the cable is rated for more than the turnbuckles.  I suppose if you're very worried about it you could use more cable and build a 'safety' out of cable that would catch things should the turnbuckle fail.

My thought on this though... over time, the cable may wear/corrode ~ it's one reason we  should have lots of safety factor in the cable.  The turnbuckles probably won't degrade quite so fast as the cable.

[HaroldCR]

 We used to buy reels of cable from a Poultry Supplier, in Arkansas. It was treated with something, and never would rust. We used 3/16. When we went to installing 4KW machines, we would use 3/16 for the lower sets and 1/4" for the top.

  We also never used Turnbuckles. There will be a certain amount of sag in the cable, under tension. IF you tighten all the guys with Turnbuckles, and one top one breaks or slips severely, the weight and tension of the others will bring down the tower.

  Also, tightening turnbuckles will exert more down force on the tower, than you realize. We used a small set of rope block and tackle, and pulled directly off the anchor.

  Installed over 25 machine, and 50 or more TV and Ham towers. Built all but 3. They were Rohn's.

  Also designed an arm to put TV Antennas and wind gauges below the Turbines, on the towers.

 

[Ungrounded Lightning Rod]

I recall from sailing that the bend from tying a knot into a line would be significantly weaker than the line itself.  Different knots had different characteristics for weakening the line, and some knots were used in particular places (i.e. anchors) to avoid hazards.

I suspect the same is true of steel cable.  The cable itself, in a straight run, has its maximum strength.  But when you bend it around something the bent section is weaker.  Thus, while a cable running around an enormous pulley might be at essentially full strength, when using it for a guy wire you use a cable thimble around the anchor point.  This gives you a smaller and well-defined reduction of the strength.

Clamps help (by transferring some force from one side of the bight to the other, in principle doubling the strength of the bent part).  But they also weaken the cable, especially where it leaves the last clamp, by squeezing it.

I bet the strength of the turnbuckles in the previous posts' examples is pretty close to the strength of the cable after derating from being bent around the thimbles and clamped.

[freejuice]

HI Folks thta is what I'm essentailly doing too, that si sliding 3-1/2 inch schedule 40 inside of 3 inch tubing  with two bolts of at least 5/8 passing completly through the tower about ten inches above and below each connection at 90 degrees r right angles to each other.

 I also will take up the slight "slop" with some morris couplings...here are the folks I bought them from. I actually got into a converstion with the guy when he called about the order...he's also deeply interested in wind turbines...so I turned him onto this site )

 The morris couplings cost me 18 bucks each they are the five bolt versions made from 16 gage material or about .065 thick, however they overlap two thicknesses for a total wall thickness of about .130 thousandths.

 While it only shows the three and four bolt models the fellow carries them in the five bolt-10 inch long versions , they come with a black neoprene insert which you can see in the add if you look close enough...you can simply discard this if you like. I have three on ahd ready to go...they are robust enough if you use a piece of pipe to line the tower junctions...the bolts on the coupling are about 1/2 inch, not bad...

 Heres the web site: http://www.globaltecheng.com/ProductCart/pc/showsearchresults.asp?idCategory=91&idSupplier=10&am
p;priceFrom=0&priceUntil=999999999&sku=s-4500&IDBrand=0&keyWord=&customfield=0&a
mp;SearchValues=&resultCnt=10&order=2&Submitx=&Submity=9&pageStyle=H

 As to using threade pipe, I would nt do it, think of the pipe in a cross sectional view, the bottom of that 60 degree "V" thread penetrates at least about the thickeness of the pipe...a major weakness beacuse pipe thred fitting are also tapered which will not allow you to "bottom out" your fittings thus your tower on day will shear off at above or below the threade section...just about anywhere the thread is exposed....a train wreck waiting to happen. Be safe and all the best!

 Gavin

[SparWeb]

ULR is right, the termination of the cable de-rates its strength.  I've done tests on these cables, and I got results that are close to manufacturer's recommendations.  When putting an eye into wire rope, using 2 or more "horseshoe" cable clamps, you can only expect 80% of the strength of the original cable.

For a tower, use a safety factor of 6.  For the 5/16" cable, then, 80% of its strength is 7840 pounds.  A safe working load is 1/6 of that, or 1300 pounds.  The working load on the guy wire will be the thrust load on the turbine and tower, divided by the cosine of the angle the wire makes with the ground, plus the pre-tension cranked into it by the turnbuckle.

The manufacturer of the turbine can give you the thrust load.  If you built it yourself you can compare to other wind turbines that have the same rotor diameter.  Fudge that number upward, too, to be safe.

[Ronnn]

Wow, This thread is full of very useful information. When 5/16 cable is mentioned as having X strength, is that a general figure for any kind of new 5/16 cable? Or is there some prefered guy wire cable type? How about what some  call woven wire rope. A well driller had some 7/16 cable pieces he wants to sell me. I think it is made like welding cable very flexable. Would this be ok to use? He uses it on his drilling rig so I guess it must be pretty strong.

Ron

[SparWeb]

...He uses it on his drilling rig so I guess it must be pretty strong.

I dunno, maybe he uses it to hold up the awning that keeps the rain off his laptop...

Yes, every wire rope has a specific strength.  There are definitely different levels of quality and construction, so do not assume it's all the same.  For a wire rope you're really going to rely upon, find out what the manufacturer claims as its strength.  They should be meeting or exceeding a military-standard minimum strength.  Getting the wire rope from a friend makes it more difficult to relate what you have with the strength specification of any particular supplier.

The more supple kind of wire rope is definitely the "aircraft-cable" construction.  To be used on an actual aircraft, the cable must come from the manufacturer properly identified and with approved paperwork.  Getting that in the hardware store, you obviously won't get the certificate!  That's okay, you're not using it on an aircraft anyway.  But it also means that you can't expect full aircraft-quality strength, either.  It's usually darn close.

A reputable supplier in the US:

http://www.loosco.com/

and for terminals, eyes, turnbuckles, shackles, etc.:

http://www.thecrosbygroup.com/html/default.htm

Just a few suggestions about what works for me.  There are many many others.

[Ronnn]

That is a really, good price for 4"schd. 40. Best I can do around here is 5 bux a foot. I thought of a conversation I had with a well driller I called about pipe prices last week. He told me when you buy pipe that is used to check for magnetism in the steel. He suggested drooping some iron filings on pipe to check. The idea being that sometimes pipe used in wells gets magnetized to the point that it becomes hard to weld. I don't understand the mechanics of that but this guy has worked as a welder for years under certification. So I'm wondering if anyone has heard of this situation. If you are getting it new at that price get it all and call me.    {;^)>

Ron

[neilho]

Most commercial towers use Extra High Strength (EHS) galvanized wire rope, which is way too stiff to wrap around a thimble. It's 1x7, meaning each strand is one wire and there are 7 in the entire rope. Aircraft cable is 7x19, so the wires are comparatively tiny, meaning much more surface area for corrosion, so it doesn't last as long as EHS wire. It is flexible, which isn't really needed for guy wires. And EHS wire costs about half as much as the aircraft cable and has a higher breaking strength rating, too. 5/16" cable, for example:  11,200lbs vs 9800 and $.45/ft vs $1.10/ft in an older McMaster-Carr catalog, just for comparison purposes.

The reduction in strength due to cable clamps/ubolts and saddles can be avoided by using a chinese finger kind of gismo called guy grips or big grips or preforms, depending on where you are in the world. They wrap around the ends of the cable and trap the thimble in the eye of the grip-they go on way easier than cable clamps and are cheaper for an equivalent load rating. They also come off easily, which is very handy for when the tower is being straightened, guy wires are being tensioned and the turnbuckle runs out of threads. Moving the grip on the guy wire takes less time than backing the turnbuckle off.  

Here's a link to a pic of a grip for 5/16" EHS cable -

http://www.cesco1.com/Product.cfm?ID=6712&MainCatagoryID=9932&SubCatagoryID=0

Cost: $6 and change each.

The guy wire ain't bad, either- $.45/ft from the same folks, though occasionally it's cheaper on eBay. One seller is oldtowerguy, who seems to have just about anything for Rohn-type towers.

Neil