Wednesday, 08 August 2012 11:00

Fat Boy Tower

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Fat Boy Tower

based upon the

vk4kdd One Man Tower


I'd been interested in Amateur Radio since I was a 16 year old, but never took that step up due to the morse code requirement, until the end of 2010 when I found out about the Foundation licence and that morse had been dropped across the board.

At that point I realised that I wanted to get myself a tower, so then a hunt for a tower that I wanted. During that time I came across the One Man Tower of vk4kkd, the tower than Kev made. I then contacted Kev, who just happened to at the time have his workshop down at Logan Village, and he invited me down to take a look at one 'in the flesh'.  I was mightily impressed by the design, as it was a tower I could changeover antennas as often as I liked without outside assistance, but didn't have the 'folding plastic' to buy at that stage, but Kev said that he was about to stop making them in the near future, and that I should order it sooner rather than later, but by the time I was ready Kev had stopped making them. This left me in a quandry, I found the tower that I wanted, but it was no longer being made and didn't know where to find someone to build one for me, let alone the design ! Then the idea came to me, why don't I build one myself ? ... I didn't have a welder, let alone knew how to weld.

Took a big time to think about it and do some research on welding, then chose to build my own. Bought myself a MiG welder that was on special at Mitre 10 for $450, then started to buy all the other gear and hired the gas cylinder. Built a steel workbench, and started to build up some jigs for the tower. In the meantime I found some owners of the earlier model of Kev's One Man Tower, and was able to check out how things where done, as well as some other stuff found on the net.

That all said, what I built was a Fat Boy Tower, it just so happens to look an awful lot like a One Man Tower, any and all mistakes are mine and have nothing to do with ones that Kev built.



Having worked out what wanted to build and what I needed to get to build it, I started on obtaining the steel. One thing I learnt real fast was to buy a cut off saw and do my own cutting !

First thing to build was the jig for the hoops that hold the tower segments together. This was made out of plate and angle steel.


You can see the jig here on top of several of the hoops.


These hoops were made from 5mm by 40mm angle, with the internal side of the hoops being 300mm. However if I was to make a new tower, I'd make the internal sides around 380mm, as the hoops then become a ladder, where you can stand with both feet.

My existing tower makes it very uncomfortable to have both size 12 feet on the same hoop. :(

The only difference is the bottom hope that bolt to your concrete base is 6mm by 65mm angle.

 The SHS used on each section was 40mm with 5mm walls, and 2500mm long, in other words 4 sections gives you a 10m tower.


 I also made up a 'rotisserie' jig so that I could weld the hoops to the SHS lengths, without having to fiddle around on the ground and possibly not make it all square.

Here you can see one section of the tower on my rotisserie, and the first two lengths of the SHS tack welded in to place, with the 4  'middle' hoops hanging off, ready to accept the other two lengths of SHS.

Once they were tacked in to place, every was checked to be square, then the 4 'middle' hoops were tacked, then the whole section checked for squareness again, before final welding.



You may notice the middle hoop has 8 holes in it, well that was me getting carried away with drilling the hoops for where the sections join, and doing too many of them ! laughing So rather than throw them out, I used them up, and in the end have come in handy to attach items to the tower.


This image shows the slider rails (5mm by 40mm angle), attached to the side of the hoops, with the slider already in place.

This shows the sliding section relative to the slider rails on the tower.


Here you can see the two sections on the slider rails that you use to put up or take down the tower. Set up this way for welding so that it all lines up together.

The SHS is more of the 5mm by 40, the collars were 5mm by 50mm tube, the other tubing was 40mm by 5mm, and the plate was 5mm by 50mm.

A closer up image, showing how the two sections line up.


Here's the Slider sections

 The slider that always remains attached to the tower is SHS 40mm with 5mm walls. The length is 800mm.

The plates that you weld to them are 280 by 65mm, and 5mm thick, and you need 4 of them made up for this section.


This is a photo of someone else's One Man Tower, which is a narrower tower, hence the narrower slides.

The stand off's on the slider are the same as my own, which are 110 x 50mm.


These next two sections are what you use to install the sections up on your tower.



This one attaches to the slider in the above, with the loop end facing the top for the next install piece.

The length of this one 800, but I later on made one 1300 in length, as it gave me more 'play' room when I installed new sections to the tower. The original length works fine, but you need to winch it up to just the right height to be able to swing the new section around. This extra 500mm makes it real easy, without running the winch hook in to the top pulley when you bring it up.

This piece slides in to the one above, which clamps on to the slider rails of the next section that goes up.

Like the main slider section, all tab/standoff sizes are the same, except for the pipe section which is 40mm x 1000mm, and the SHS section which is 600mm long.


Once you have the tower installed, you replace the two above sections with the following section, which you put your rotator on to. This photo shows it next to the slider of that other persons OMT.


 Here the tubular sections are 50mm diameter to allow a 40mm pipe to turn around inside of them

The SHS is 1700mm long, and the tabs/standoffs are 70 x 190mm to allow room for a rotator. I chose the Alfaa Spid rotators as believe they are best money can buy.

The middle guide is at the standoff's for the slider to aid in strength.

Also, note the tab at the back of the slider, with a hole in it where you attach the wire rope to from the winch.



These two photos show the bevelled edges of the slider, and the 5mm plate welded in place help guide the slider section up and down the tower, and the extra plate to help strengthen things.



This is where we continue on with the tower's construction.


Something not mentioned earlier, is the hoops, where one section joins another section.  You need to drill 8 holes in each to allow you to bolt them together. I drilled 18mm holes in order to put 16mm bolts through them, and taking in to account not everyone is perfect, the extra 2mm allows "fiddling space" to get the bolts through.


 This shows slider in position with a pole in place to ensure it all lined up together to the rotator's location. Tower section is still on the rotisserie here.


Looks better when it is vertical ! cool

If you turn your head sideways, you can see how the rotator and pole would sit in place. I even had a 2 element 40m Quad up the top of it at my old place.


Each 2.5m section was built individually, and when completed, was taken to get hot dipped galvanised. Even though we're nowhere near the sea, so no salty air, I felt it would be so much better to have it galvanised than painted.


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