Author Topic: New Tower Build (Read 7210 times)

SparWeb · « **Reply #33 on:** October 27, 2021, 03:38:25 PM »

Ruddy,
You and I both remember well these lessons well from the days the Dans wrote so many tower raising stories...

SparWeb · « **Reply #34 on:** October 30, 2021, 11:20:40 AM »

A couple of disappointing discoveries this week.

1- The cable on my winch is damaged. I have to replace it. Overall I guess I'm glad I spooled out all the cable to make sure it was long enough and inspect it - finding damage is what we do inspections for, after all.

2- The earth pile for the winch is offset from the line of the gin pole rather substantially. I had wanted to offset it by a few inches so that the gin pole could come down on the ground without hitting the winch. Well, I overdid it, and the winch is more than a foot to the right of the gin pole. That could make some awkward cable alignments.

I guess the math tells me that 1 foot to the right of a gin pole 30' long makes an offset angle of about 2 degrees. That puts 30 pounds of load on the gin sideways, for every 1000 pounds of tension on the cable. I already planned to put stabilizing cables on the gin pole to keep it from swaying side to side. Now I guess the left one will be tight all the time.

kitestrings · « **Reply #35 on:** October 31, 2021, 06:03:23 PM »

Re: 2) Could you just mount a sheave, or cable guide that is offset on end the gin?

SparWeb · « **Reply #36 on:** November 02, 2021, 12:37:14 AM »

That's about all I can do, without sticking something else into the ground.

I've turned the winch around to face the other way. The cable will go AWAY from the tower first, to the North anchor 10 feet away. Then it goes through a sheave at that anchor to the tip of the gin pole. When the gin pole lowers close to the ground, the angle of pull on the cable will be next to useless. Thankfully when the gin pole is horizontal, the tower is vertical, and the operation is done.

The sheave also has to be on a swivel to allow it to pivot to various angles during the lift. I found that I have an okay-ish swivel but I'd like a more beefy one.

If this plan doesn't work out putting the sheave at the North anchor, I will have to put another anchor in the ground dedicated to a sheave wherever it really needs to be. Or relocated the winch. Shrug.

For readers who don't know what I'm talking about, don't despair, I don't think I'm explaining it well. When I get this finished and working I can post an aerial view drawing, and then the "uh-oh" will be pretty obvious.

SparWeb · « **Reply #37 on:** November 12, 2021, 02:53:55 AM »

I got the winch figured out.
It's not perfect, but nothing is being dragged sideways.

Actually, it's nice to have the gin pole not coming down right on top of the winch. The placement of the winch under the gin pole would have been very inconvenient, if they had been lined up. Having passed the winch cable out to the guy anchor, through a pulley, and back to the end of the gin also makes the cables easier to handle. It winds on and off of the winch drum very neatly.

There's a mess of cable on the ground in the photo because I haven't cut the loose ends yet. I can do that now, just wasn't in a hurry to do it on 1st lift day.

SparWeb · « **Reply #38 on:** November 12, 2021, 03:00:17 AM »

Oh, and I almost forgot: Yay, it's up!

Mary B · « **Reply #39 on:** November 12, 2021, 12:43:53 PM »

Always feels good to have things up and vertical! My projects are on hold... I might get concrete poured for the front stub tower next week and put a heater under a tarp to keep it above freezing for a week but the 30 footer I want warmer weather, it has a LOT more stress on it than the 5 foot stub tower for the dish antenna!

kitestrings · « **Reply #40 on:** November 15, 2021, 04:18:14 PM »

Congrats! but, but wait... where is the turbine ;>0 ?

SparWeb · « **Reply #41 on:** November 15, 2021, 08:25:09 PM »

The cold weather has held off for longer than I have any reason to expect.

Yes!
Turbine mounting to come soon.
Installing the drop cable is actually the next step.
Oh, and I decided to put a Cat5e cable in the trench before closing it up.

With that in place the turbine itself will not take long. It's the same head mount from the last tower.

kitestrings · « **Reply #42 on:** November 16, 2021, 09:36:17 AM »

...and you'll use a gin-pole and winch for that? I was thinking you had tilted the tower with the turn=bine in the past.

Mary B · « **Reply #43 on:** November 16, 2021, 11:53:04 AM »

Climbing a BX style tower really really really sucks... and is hard on the webbing

SparWeb · « **Reply #44 on:** November 16, 2021, 09:57:41 PM »

Yes. I'm not going to be climbing this tower, if that's what you're wondering.
Mary's first-hand experience with these DMX towers, which she referred to as "flimsy" would definitely be the impression given to a person attempting to climb it on the cross-members. No thanks. I really don't have a problem with heights,myself (hobby rock-climber in my 20's). But when I think of handling the massive stuff up there and all the push-pull I normally do mounting the turbine... Nah, I'll do that stuff on the ground, thanks.

If it's of interest, the tow cable tension at the start of the lift, with the turbine installed, is estimated to be 1190 pounds.
This is based on a model that I wrote many years ago, then cross-checked with a load-cell attached in series to the tow cable on my old tower. It's 1st-year mechanical engineering statics, really. Today I revised it to increase the power cable weight to 50 pounds, based on the massive 8/3 thing I just bought. There's still a big safety factor.

kitestrings · « **Reply #45 on:** November 17, 2021, 05:05:29 PM »

So, "check" that box, the practice run went off without a hitch, right? Anything you will do differently with the turbine on it?

SparWeb · « **Reply #46 on:** November 17, 2021, 10:58:59 PM »

I have another test-lift to do, yet. I want the bugs out before lifting the turbine up.

One thing I've added is a shock absorber to the backstay cable. This may be hard to explain with words...
When the tower is nearly vertical (about 5 degrees from straight up) it starts turning vertical on its own. No need for the tow cable any more, because the CG of the tower has already passed over the two hinged legs. As a result, I needed a block under the third leg to stop this from happening. I anticipated that, and I was ready, but that was not a smooth way to operate. So beside the back-stay cable anchor I've screwed in another earth anchor. To that, I've attached a cable with several big springs in it. The backstay cable is hooked up like it always was, but the first thing to come tight is actually the cable with the springs. The springs can stretch and slow the tower down in its last few inches before the 3rd leg comes down to its mount.

That's the theory. If it actually works and looks like something others can try to use, I'll take some photos and explain in more detail. I still haven't figured out how to disconnect the springs from the backstay cable so that it can do its job normally when the tower is bolted in.

It's dark in the evenings, now that we're on standard time zone. I will test this on the weekend, and passing that test, it's full steam ahead to reassemble the turbine and get it up in the air.

DamonHD · « **Reply #47 on:** November 18, 2021, 02:58:49 AM »

Another fascinating solution to an interesting side-problem that you might not even have anticipated!

Rgds

Damon

bigrockcandymountain · « **Reply #48 on:** November 18, 2021, 09:15:51 AM »

Mine does that too. I have thought about putting a weight on the back cable, like about 50 lbs and attaching it about 5 feet up, so it doesnt pick up until the tower is almost vertical. So far i just deal with it jerking a bit.

Good luck. It sure looks good standing.

Mary B · « **Reply #49 on:** November 18, 2021, 11:16:23 AM »

Quote from: SparWeb on November 17, 2021, 10:58:59 PM

I have another test-lift to do, yet. I want the bugs out before lifting the turbine up.

One thing I've added is a shock absorber to the backstay cable. This may be hard to explain with words...
When the tower is nearly vertical (about 5 degrees from straight up) it starts turning vertical on its own. No need for the tow cable any more, because the CG of the tower has already passed over the two hinged legs. As a result, I needed a block under the third leg to stop this from happening. I anticipated that, and I was ready, but that was not a smooth way to operate. So beside the back-stay cable anchor I've screwed in another earth anchor. To that, I've attached a cable with several big springs in it. The backstay cable is hooked up like it always was, but the first thing to come tight is actually the cable with the springs. The springs can stretch and slow the tower down in its last few inches before the 3rd leg comes down to its mount.

That's the theory. If it actually works and looks like something others can try to use, I'll take some photos and explain in more detail. I still haven't figured out how to disconnect the springs from the backstay cable so that it can do its job normally when the tower is bolted in.

It's dark in the evenings, now that we're on standard time zone. I will test this on the weekend, and passing that test, it's full steam ahead to reassemble the turbine and get it up in the air.

Like a screen door spring in a spring on the chain where they pull opposite ends of the spring pack to absorb shock if the wind catches the door and slams it open...

Mary B · « **Reply #50 on:** November 18, 2021, 11:20:10 AM »

We always used a rubber pad under the tower braces when tilting a loaded tower up... some of the ham radio stuff I have helped on has been massive, this job we had to use a crane, tower itself weighed in at 8 tons...

SparWeb · « **Reply #51 on:** November 19, 2021, 08:37:14 PM »

Yes, you guys have it. And it's a lot like a screen door spring, too.

I tried a tower tilt with the spring in place today. It didn't work well, but nothing went crazy on me so I'll keep trying.
The spring I used is actually much heavier than a screen-door spring, and that's probably the problem I had.

Here's what I really need:
Take up about 12 inches of slack on the back-stay cable. When fully extended it only needs about 25 pounds of tension. That's a pretty soft, long spring. The spring I started with needs about 100 pounds to extend about 4 inches. Once I had my hands on these things and pulling it myself I realized that the balancing force the tower needs is very very small.

Since I love math: 25Lb/12inch = 2 Lb/in spring constant. I think I started with a spring constant of about 40 Lb/in so it was pretty obvious that it wasn't helping.

SparWeb · « **Reply #52 on:** November 19, 2021, 08:42:45 PM »

Actually, there was a moment of excitement.
I hadn't yet cut the long loose ends of the guy-wires yet. So there were some 1/4" steel cables dragging around. And there was this moment where I dragged the cable across the battery terminals!

Zap

Fortunately this didn't strike on the GOOD end of a cable.

SparWeb · « **Reply #53 on:** November 19, 2021, 08:53:39 PM »

The rest of the lift and lower went smoothly.
All the cables are cut to final length, all the thimbles are tight, and all the saddle clamps have been torqued (twice).
The winch pulls it up in less than 4 minutes and lets it down in 3. The pulley on the forward anchor seems to be in the perfect position.
One of the side guy wires needs to be completely disconnected for lowering. I thought I had the anchor shifted off the hinge axis but apparently not far enough (by 6 inches).
Earlier, I had mentioned that the tower's hinge axle ended up turned relative to the diamond pattern of the guy wires. This is the cause of the too-short guy wire, but that's manageable, especially with a truss tower, that doesn't really need side-guy wires connected during lift/lower. This also causes the winch to be offset from the gin pole but that's ended up being a fairly happy accident, because I can deal with the gin pole without stepping over the winch.

To top it off I have all the cables buried in the trench.
4x 3 GA for 3-phase Star AC turbine output
3x 12 GA for 120VAC electric power (e.g. winch upgrade)
1x Cat-5E if I ever want to add a weather station or something.

SparWeb · « **Reply #54 on:** November 19, 2021, 09:01:13 PM »

For those of you thinking this is super spendy (and I have to agree with you) some of the big-ticket items have been scrounged over the years.
The buried 3-gauge cables were removed from a commercial building where I worked during an upgrade.
All of the 1/4" steel guy wire cables came from an aviation company that was disposing of "surplus" cable. This stuff is the same spec used for aircraft control cables, jeepers.
The tower itself was bought used, and a whole bunch of parts from my old tower have been re-purposed for this new tower, such as the gin pole and the winch.

Mary B · « **Reply #55 on:** November 20, 2021, 12:26:55 PM »

Friend had a telephone pole set 5 feet away from a Rohn BX tower. Pole had a winch and cable to a pulley at the top and the cable connected to the tower.

Talk about sketchy with 100 pounds of antenna/rotor/cables on the tower! Telephone pole BENT under the load! I always hated helping lower that thing for repairs!

SparWeb · « **Reply #56 on:** December 12, 2021, 07:11:17 PM »

OK

Final countdown to completion

Generator Installed:

Zubbly-style motor-conversion

SparWeb · « **Reply #57 on:** December 12, 2021, 07:13:35 PM »

Blades Mounted:

Hand-carved cedar laminates, 10-ft diameter.

SparWeb · « **Reply #58 on:** December 12, 2021, 07:16:16 PM »

Portrait of a proud (and anxious) builder.

SparWeb · « **Reply #59 on:** December 12, 2021, 07:18:53 PM »

Last check of all cables, bolts, and tools to fasten them...

Then, an interminably slow process with a loaded winch...

Then, really busy securing this, that, and everything..

Then you stand back and there it is.

SparWeb · « **Reply #60 on:** December 12, 2021, 07:19:46 PM »

Then, just waiting for the wind.

SparWeb · « **Reply #61 on:** December 12, 2021, 07:22:15 PM »

I didn't have to wait the usual day to see it start turning.
In violation of the windwright's curse, the wind actually did pick up 3 or 4 hours after it was raised, and even now it's humming along at about 250W in a breeze I can barely feel at ground level.

kitestrings · « **Reply #62 on:** December 12, 2021, 09:31:19 PM »

Whahoo! Congrat's! That looks great, and those blades are awesome Spar. Hope it all runs smoothly. I'm sure it will. It's the raising/lifting that is nerve wracking. Breathe a sigh of relief and take everything in... well done.

How high is the new tower?

MattM · « **Reply #63 on:** December 12, 2021, 10:05:20 PM »

video! video!

That is something to be proud of. Thanks for sharing!

MagnetJuice · « **Reply #64 on:** December 12, 2021, 10:52:02 PM »

CONGRATULATIONS!

Great job Steve.

SparWeb · « **Reply #65 on:** December 13, 2021, 12:27:35 AM »

Thanks everyone!

It's exactly 70' (21m) from ground to hub centerline.
As shown earlier, it was made from a DMX-68 lattice tower. Understanding that a stock DMX is not sturdy enough on its own to handle a turbine of this size, I set about reinforcing its topmost members, and providing for 4 guy wires.

The base also has a hinge feature, allowing the whole tower to be tilted by the winch, a process that takes 3 (long) minutes. The gin pole and winch can be removed once the tower is up, but frankly they're heavy and awkward, and there's nothing really convenient about doing that, so I think they'll stay where they are permanently.

The first objective was to finally have the turbine well clear of all treetops in all directions. Ever since raising my first tower in 2009 when I thought these saplings would grow to 30 feet, I have been annoyed by the 50-footers they actually grew into.

The second objective of the new tower is to relocate it to a much more useful location on the property. This tower's buried cable travels to a garage that's less than 100 feet from the utility pole. When and if I decide to plunge into grid tie, this turbine can now be a part of that plan.

News:

Author Topic: New Tower Build (Read 7210 times)