Fabricating a 100ft tip up mast

[Bill Glynn]

The description below was interspersed with pictures but when I tried to post it had too many pictures. I've deleted all of the pix but one and left the text. The rest of the pix can be found at https://www.greenpowertalk.org/album.php?albumid=32

After making the decision to add wind to my system I decided to build the support mast myself. I'm not a professional welder but have been joining metals since childhood. My welds aren't pretty but none have failed so, while the project was somewhat daunting, I dove into it.

I can't take credit for the design. tip ups have been used for broadcast, two way and wind, among other things, for a long time. This is just one of the many types of tip ups.

The mast and gin pole sections are made from 20ft lengths of 12ga. 10in. tubing. The hinge cups and mast and gin pole caps are made of 10in. schedule 40 pipe. Tubing diameter is measured outside and schedule 40 pipe is inside so the tubing fits inside the pipe. The coupling sections are 2ft lengths of tubing slit lengthwise. 1in flat stock was used to make the bolt clamps. The couplings were also welded to the tubing.

The top section is a 13ft. length of 3 1/2in schedule 80 pipe. 7ft. extend above the top of the 10in. cap. The rest is down inside the top section of 10in tubing. A plate of 3/16in. stock is used to center the schd. 80 in the tubing. The top flange is a 7in. square of 3/4in. stock.

The hinge is made with a length of 3 1/2in. sch 40 inside a length of 4in. schd 40. The winch mount is a length of 8in. angle 1/2in. thick.

Work started with the layout of the project and excavation for the mast base and anchors. Forms were used for the mast base and winch anchor. The other anchors were just poured into the holes. All holes and forms were bigger at the bottom. Like truncated pyramid. Lots of rebar too. The J bolts used for the winch and base are hooked to the rebar for strength.

The prep used for painting is a phosphoric acid compound.

It rained a lot so I had to put up a tent to work out of the rain.

Daytime high temp was about 10F.

My neighbor Kirk helped with erecting the structure.

Had to stop work when the moose came through the property.

The pin is a length of 3/8in. rod peened over on the ends. It is loose in the hole. This allows the mast to move some as the wind works at it.

We had been using the battery for the winch all week and it gave out as we started lifting the turbine. Had to use the truck and jumper cables to finish lifting. When the battery is charged, it has no trouble lifting the turbine.

https://www.greenpowertalk.org/picture.php?albumid=32&pictureid=417
A total of 11 yards of concrete was used. 2yards each at the mast base and 3 of the guy anchors and 3 yards at the winch.

[Rob Beckers]

Very impressive Bill!
Did you really make this out of 10" diameter pipe? That tower must weigh a few pounds.... Some years ago I had a 100' tilt-up tower designed for a 6kW turbine (the Eoltec Scirocco), and we used 5" sched 40 pipe in 20' sections. Structural analysis showed that to be plenty.

Very nice tower though! How are the wind speeds up there?

-RoB-

[Bill Glynn]

Hi Rob,

Thanks for the comments. I appreciate them.

No. I did not use 10 inch schedule 40 pipe. The mast and gin pole are made of 20 foot lengths of 10 inch thin wall tubing. In the post I said 12ga. but it really is 10ga. The tubing wall thickness is the same as 10ga. wire. While heavy at about 225 pounds each, one person can move a 20 foot length. 10 inch schedule 40 pipe has a wall thickness of about 5/16 inch and is hundreds of pounds heavier. Would take a small crane to lift one.

The only 10 inch schedule 40 pipe used was for the 10 inch cups on the hinge and the end caps for the gin pole and the top of the 10 inch mast where it transitions to the 3 1/2 inch diameter length of schedule 80 pipe supporting the turbine.

As mentioned in the original post, tubing diameter is measured outside while schedule 40 pipe ( in this size range ) is measured inside. A 20 ( or any ) foot length of 10 inch tubing will slide into a 20 foot length of schedule 40 pipe.

Kasilof is not considered a high wind area. The reason my location works is because it's near the top of the ridge overlooking the Kasilof River valley to the south. That puts us up in smoother wind and also gives us the benefit of the afternoon thermals that come up from the river. The Kasilof River also drains into Cook Inlet. This is a very large body of sea water covering well over 6,000 square miles. It has tides as large as 20 feet! That's a lot of air that must be displaced. Much of that volume of air gets pushed up the river valleys and contributes to turbine output.

Most of our wind is under 35 mph even during storms but the turbine has seen storm wind gusts between 80 and 100 MPH without incident.

Bill