40' Tilt-Tower Design

[bzrqmy]

I have had some ideas bouncing around in my head for a 40' Tilt-up tower.  My hope is that in the event of a cable failure, my tower will not immediatly come crashing to earth.  In strong winds, nothing will stop it, but I would like a chance to remedy the situation.

The thing about this design is that I can get the structural steel from a local scrap yard and the hardware from a farm supply store.  I got the 3" Schedule 40 pipe from a well driller.

The tower will hold a 10' otherpower turbine.  If the 10 footer works, I will be building the 17 footer in the future.

The tilt assembly is made from (2) 12" lengths of 10" C-Channel.  The hinge is 2" schedule 40 pipe over 1 1/2" pipe.  The 1 1/2" pipe acts as the hinge pin.  The 2" pipe is cut into 2" lengths and welded to each of the C-Channels to form a hinge.

Not shown in the pictures is the concrete base.  Not exactly sure what to use here, but I was thinking about 18" x 18" square pad at least 36" deep.  The pipe protruding horizontaly is a 4" length of 2 1/2" pipe that my 3" x 20' gin pole will slip over.

The bolts holding the fixed C-Channel (Green) are 1"x8" long and have rebar welded in a cage assembly that can be buried in the wet concrete.  The other two bolts are welded to the fixed C-Channel and will lock the pivot assembly once in the up position.

Also not shown is the rest of the tower.  Basically (2) 21' lengths of 3" pipe with a threaded coupling.  I will be using (2) 3/8" chain links, (1) welded to the pipe just below the coupling, (1) will pivot free and have the 1/4" cable looped through it.  There will be a similar arrangement at about the 35' height.

The cable anchors are going the be the screw-in earth anchors.  I don't trust them screwed in the ground, so I will be digging holes and embedding them in a couple bags of concrete.  I will be welding the loop closed and welding some extra junk to the buried part of the anchors.  Seems like I saw someone slipping brake rotors over the anchor, what a swell idea.

The plan at this time is to use one turnbuckle for both sets of cables.  Maybe someone can talk me out of it, but I just spent $80 on (4) turnbuckles and I'm going broke.  I can't belive how much $$ this thing is consuming.

This design is virtural at this time, but soon to be a reality.  I purchased the hardware today, the 1/4" cable is on the way.  I plan on visiting my local scrap yard this week to get the C-Channel and pipe.

As soon as I can break myself away from this obsession, I need to fix my truck so I can go get my concrete.

Alright, any suggestions before I start fabing this?

[electronbaby]

Your design looks ok for a 10' turbine, although Im not sure of your wind regime. I am located in the US in southern NY (Long Island) and we have 120 mph basic wind speed design guidelines we need to follow. I am unsure about your location, but I hope you see what Im getting at...

DONT USE THREADED PIPE COUPLERS. You are asking for disaster. Try to use a outer coupling sleeve, and weld if you need to. Threaded couplers fail.  

Dont expect your 3" pipe tower to hold up a 17' turbine. This will come into play once you are bored with your 10'. You will most likely need a more substantial tower for the 17'.

Usually, with tilt towers, it is advisable to play close attention to the side anchors, and how the guys connect to the in ground anchor. When the tower is lowered, you will have some lateral force on the anchors, and depending on how you build them, you run the risk of bending your anchor eye when lowering or raising the tower.

Just some pointers, good luck :-)

[Dave B]

Just a couple thoughts. Moving the gin pole connection to the tower lower and closer to the hinge will help the mechanical advantage. Also, I'd say a solid axle and pipe over it for your hinge assembly would be much less complex and stronger than fabbing a leaf type hinge with so many welds. Just my opinions.  Dave B.

[imsmooth]

I agree.  It started to happen to me.  So I made a T-bar out of 1/4" thick angle iron.  It is about 3' across and 4' tall.  I drilled a hole and using 5/16" chain I attached a pulley.  The T-anchor is in pure tension so there is no bending moment.  If you look at http://www.mindchallenger.com/wind/wgpage12.html you can see the top of the T-anchor sticking up from the hole.  I will get pictures of the pulley and chain when the rain stops and see if I can remember which rigging store I purchased it from.

[luv2weld]

pipe with a threaded coupling.  I will be using (2) 3/8" chain links, (1) welded to the pipe just below the coupling, (1) will pivot free and have the 1/4" cable looped through it.  There will be a similar arrangement at about the 35' height.

What has already been said. Do not use threaded couplings. You lose over

half of your pipe strength.

I don't understand the chain links. Is this the only thing you have for

guy wires??? Just 2 pieces of chain. Only 2 guy wires??? Then later

you talk about 4 turnbuckles???

Personally, I would not use one turnbuckle for 2 guy wires. The expansion and contraction will not be the same because the length of the

the wire is different. You do not have to use turnbuckles on every

guy wire. It just makes it a lot easier to adjust them. You just have

to be willing to go through the extra work of adjusting the wires

without them.

Ralph

[imsmooth]

Ok.  I posted a picture on the page above.  The pulley is from cmi-gear.com.

MBS = 7500lbs

[electronbaby]

Usually an equalizer plate should be used for multiple guy connections terminating in a single anchor attachment. This has the ability to allow the tension to be equalized between both guys and makes things a little safer when raising, lowering and adjusting the guy tension over the complete range of dynamic motion that is happening to the guy tension when the tower is under load.

[prasadbodas2000]

I have used such a hinge in my first project 12 footer. Please see the photo. I hope that the hinge details are clear. Basically 2 Inch Nominal Bore (NB) GI pipe is the tower. A full threaded thick coupling welded to the base plate from below. It connects to a pipe piece which is inserted in the concrete foundation. The upper tilting plate has a 2 Inch NB equal TEE welded to it so that the 2 free ends can be used to screw the main pole and lifting pole. The two plates have 6 nos matching holes for bolting after installation. At one edge the two plates were welded alternately to a 3/4 Inch NB thick walled pipe. This pipe was then cut between the alternate welds to allow rotation. A round steel bar inserted in this small dia pipe serves as the bearing rod for the hinge.

The tower pipe has 2 levels of ropes 10 and 20 ft from ground. Machine sits at 26 feet height. Machine has

. 265 mm dia, 2 nos magnet discs 12 on each 2x1x0.5 inch sized NdFeB N35 magnets

. 3 ph with total 9 coils of 60 turns each of 15 Gauge wire

Unfortunately the wind data is not measured at the site. Since 1st Jan 2009 it has been working fine and producing about 100-200 Watts in winds of 5-12 mph (wind speed is only an estimate)approximately.

I am yet waiting for good wind speed and to observe furling behaviour.

In my opinion hinge at the tower base of this sort is fine to be of any reasonable mechanical design, but for sure it can not be used to prevent falling if any of the guy ropes fails.

[DanB]

I'll throw out some comments for what they are worth...

'I have had some ideas bouncing around in my head for a 40' Tilt-up tower.  My hope is that in the event of a cable failure, my tower will not immediatly come crashing to earth.'

I think it will - the base will not hold up the tower, especially a tower of fairly small (3") pipe.

  'In strong winds, nothing will stop it, but I would like a chance to remedy the situation.'

I'd worry more about preventing a cable failure than hoping to build a base that will support a tiltup tower without cables on it.

'The tilt assembly is made from (2) 12" lengths of 10" C-Channel.  The hinge is 2" schedule 40 pipe over 1 1/2" pipe.  The 1 1/2" pipe acts as the hinge pin.  The 2" pipe is cut into 2" lengths and welded to each of the C-Channels to form a hinge.'

The hinge looks workable although I prefer a looser hinge that gives a bit more slop side to side.  We'll often use 3" pipe over 2" pipe or something.  The hinge will not support your tower in any way - if the guy wires are off at all or it's inclined to go one side or the other, it'll just tear up the hinge, bend the tower, move the pad etc...  I would rather have slop in the hinge.  Not necessary if you get everything perfect though I suppose.

'Not shown in the pictures is the concrete base.  Not exactly sure what to use here, but I was thinking about 18" x 18" square pad at least 36" deep.  The pipe protruding horizontaly is a 4" length of 2 1/2" pipe that my 3" x 20' gin pole will slip over.'

That should be fine but I don't think a great concrete anchor at the base is that necessary.  Again, the base is not going to hold the tower up on this sort of tower - the main purpose of the base is to keep it from sliding and keep it from sinking!  So a wide shallow pad maybe more appropriate.  We often just build a metal base and stake it down.  If the tower works properly, all the forces should only be down on the base.

'The bolts holding the fixed C-Channel (Green) are 1"x8" long and have rebar welded in a cage assembly that can be buried in the wet concrete.  The other two bolts are welded to the fixed C-Channel and will lock the pivot assembly once in the up position.

Also not shown is the rest of the tower.  Basically (2) 21' lengths of 3" pipe with a threaded coupling.  I will be using (2) 3/8" chain links, (1) welded to the pipe just below the coupling, (1) will pivot free and have the 1/4" cable looped through it.  There will be a similar arrangement at about the 35' height.

'The cable anchors are going the be the screw-in earth anchors.  I don't trust them screwed in the ground, so I will be digging holes and embedding them in a couple bags of concrete.  I will be welding the loop closed and welding some extra junk to the buried part of the anchors.  Seems like I saw someone slipping brake rotors over the anchor, what a swell idea.'

Should be reasonable if depending on the anchors and the earth.

'The plan at this time is to use one turnbuckle for both sets of cables.  Maybe someone can talk me out of it, but I just spent $80 on (4) turnbuckles and I'm going broke.  I can't belive how much $$ this thing is consuming.'

Maybe with equalizers but I'd have turnbuckles on each cable.  I think it's worth the extra $80.

[Rover]

Ok ... I'm a newb at this but with my 30' 2" pipe , before it became freestanding, I poured 2 concrete pillars (36" tall at 6" diameter)  that sandwiched the pipe . The base is roughly 4x4' and down 36" with literally a ton of concrete. The pillars have an axle of 3/4" steel rod running through one pillar and then the tower pipe  then other pillar , and a lock axle at the bottom of 5/8" rod (removable) running through everything again. With the guys removed it would freestand with 45 lb 7" mill, though I would not leave it up in the wind.

Is it possible, dimensions and height could be adjusted  in this case?

[frackers]

You might want to look at the pictures I've just updated on my web site here. I've added quite a few detailing the mast, the fixings, pivot, gin pole, turnbuckles and anchors.

[SparWeb]

This picture might give you some helpful ideas.  This tower is also made with 3" pipe.  The 3" gin pole you see is bolted to a 2.5" diameter pipe inside it.  The 2.5" pipe is welded to the 3"  cross-tube.  The cross-tube has a 2.5" pipe inside it, which is welded to the channels.  The 3" cross tube rotates around the 2.5" pipe, with some slop for crooked angles.

You can get more ideas from this Otherpower page:  http://www.otherpower.com/otherpower_wind_towers.html

Good luck and work carefully.  Expect the tower project to cost more $$ than the windmill!  If you refuse to spend money on it, are you working safely?  Questions of safety come up in virtually every decision you make.