Tuesday, July 18, 2017

Tower Prep -- Almost (but not quite) Vertical

The big tower is still not up even though there has been a lot of activity. Consider this list of tasks I have been up to recently and you'll see why:
  • Repairing tower sections
  • Cleaning, scraping and repainting tower sections
  • Making the first set of lower guys
  • Gin pole design, construction and testing
  • Acquisition or refurbishment of a multitude of hardware: splice bolts; thimbles; turnbuckles; shackles; tower guy yokes; etc.
  • Transportation of tower sections to the site
There are also the environmental challenges such as a continuing very wet year, delay in my neighbour harvesting the hay crop and ticks. Of course tower work has to fit around the other items that fill my days. It is all taking longer than I'd like. Big stations involve big work.

Consider this a progress report. You'll get an idea of what's involved in working with big towers if you've never done this before. Most hams never do, and for good reason! None of this is a surprise to me and went into my plans from the start.

Bending jig

Used tower will usually have flaws. Commercial tower when taken down is often not treated with tender loving care since its resale value is rarely more than as scrap metal. Ham towers may be mistreated or carelessly handled. Expect to do some repairs.

In my case several sections had bent metal at the splices and a number of dented diagonals and girts. All were reparable without too much trouble. A few questionable damage areas were discussed with an engineer who knows this tower very well.

For example, several of the sections had old welds at the splices where they were tack welded for continuity assurance in an AM broadcast antenna. I removed those with a hand grinder so that the sections would smoothly slide together.

Simple bends were repaired with a block of wood and a small sledgehammer or with a pair of large adjustable wrenches. For the few cases where these were not effective I constructed a bending jig to hold the tower section while I applied some extreme force with improvised tools and snipes.

The jig is quite simple as can be seen above. Two short 1' screw anchors hold the ends of a heavy chain that is adjusted to fit snugly over a tower section adjacent to where the damage is located. This allows a force far greater than the section weight (120 lb) to be applied to the area to be bent with a long pipe acting as a snipe. When some of the force is axial to the tower I pressed lengths of rebar into the ground to prevent the section from sliding.

The jig also serves to hold the section in place while another is slid into the splice area. I did this to confirm proper alignment of the sections and holes for the splice bolts. Doing this on the grass helped since I was working alone and the heavy sections could be dragged into position.

Cleaning and painting

When I had 7 good sections (base section included) to reach the second guy station at 70' I set up an assembly line to clean and paint them.

This is a tedious process although not difficult. I stood them on the ground where the sun would be blocked from mid-afternoon onward -- never paint in direct sunlight. With a hose I washed off the dirt and debris that collected from years of outdoor storage. Stubborn stains were scrubbed off.

I then removed loose paint and rust spots with a set of steel wire brushes. There was little rush despite the tower's age. The sections are hot-dip galvanized and then had the standard aircraft red and white paint baked on at the factory. But they're old and needed to be refreshed. Frankly I could have skipped all of this since the tower will certainly outlive me. I expect the tower will be demolished if it's still standing when I move on.

Unfortunately galvanizing requires a special primer before the metal rust protective paint can be applied. I used the primer to cover the bare spots and then painted over the damaged and primed areas with the finish coat. To avoid an overly odd appearance I painted the exterior of all sections. Now all the sections are white except for two sections that were never painted (bare galvanized steel). I was free to use any colour since at 150' the tower is too short to require aircraft hazard colour banding.


From the house yard the travel distance to the tower site is ~150 meters (500'). I cannot carry these sections on my own at all and it is very arduous for two strong men. Since I had no intention of conning a friend (or friends) into doing this I had to devise something to allow me to transport the tower sections on my own without undue effort.

Indeed I prepared for this two years ago. After I transported the sections to my home in Ottawa and paid several teenagers to load and unload them and stack them in the back of my yard I knew that I'd need a wheeled device if I was to be able to move them on my own. So I designed and built a very simple device with a couple of scrap lawnmower wheels, a short length of 2x4 lumber a threaded rod and a few fasteners. Simple it is but it works and has been heavily employed recently.

The device can be seen in this photo taken after the 7 repaired and painted sections were moved to the tower site. It is still attached to the second section from the left. Two bolts secure the lumber platform to the splice bolt holes in the section. The 120 lb sections are moved rickshaw style but with the driver facing backward to avoid being poked by the unforgiving tower legs. Attaching and detaching the device takes no more than a minute and usually can be bolted and unbolted with fingers alone.

Although the wheels are small it has had no trouble dealing with the countless rocks, holes and vegetation along the route and more than a few tight turns. The design isn't perfect and I've had to occasionally adjust the wheel nuts and threaded rods when one of the wheels locked up. If I'd built two of them transport would have been easier though at the expense of doubling attachment and detachment time and more cumbersome towing and steering. Feet are nimbler than wheels.

Where it fell short was with the base section. The device can only attach to the top of the section so the other end, the heavy end, had to be carried. That was fine while working with it in the yard but not for the long route out to the site. Although it looks smaller the base section is heavier than the others. So I improvised.

I admit it looks ridiculous yet it worked. The heavy base plate fit nicely inside the front end of the wheelbarrow frame without interfering with the wheel. Since the plate is rectangular and not suitably oriented with any of the section legs it has a habit of trying to twist the section and whatever (or whoever) is holding it. This includes the wheelbarrow, as you can see.

A little bit of muscle is needed to keep the wheelbarrow level during the tow out to the site. What I couldn't do was make turns of small radius. In several places I had to turn the section by hand and then remount it on the wheelbarrow. Despite these inconveniences the trip was done in less than 10 minutes. You can see that I used the system to carry scrap lumber and other material out to the tower site.

But wait, there's more!

The 7 completed sections are less than half the total of 15 sections I am raising. There are 8 more of them to be cleaned and painted.

When I took the adjacent picture the metal was repaired and I had done a first pass with a wire brush. There is more scraping and painting ahead of me even while I go about the task of getting the first set of sections up in the air.

Coming up

All going well tower raising will begin shortly. I will follow up with articles on my gin pole design, guy design, temporary support for the lower sections (until the first guy station is reached) and other topics that may be of interest.

In the meantime I have other station work to perform on the Trylon tower. My T2X rotator is acting up again, coax will be upgraded and I need to adjust the yagi positions to better accommodate rotation loops. I have even been doing a little bit of operating and contesting though nothing serious during the warm summer months.

I'll leave you for now with the following pretty picture. This is looking east from the house toward the field where the tower is going up in the aftermath of a storm that moved through as I was wrapping up this article. Imagine if you will a 150' tower rising from behind the trees in the centre of the picture and piercing the rainbow. It will easily rise that high.

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