The Post-Hurricane Tower Work is Finally Done

Taking a look at previous posts about the tower damage I sustained back in Tropical Storm Ian at the end of last September, it appears the last mention of what I was working on was on January 22nd, three days before my surgery.  I had said I expected to have the short term fix in place before the surgery (Jan. 26).

Knowing the surgery was coming and that I'd be restricted by that in my ability to work for the heart of the best time of year to work on towers and such hardware, I came up with a workaround: a short term and a long term fix.  The short term fix is up there now, but I need to improve that a bit and that should be done before the mandatory time off.  The long term fix is to change my whole method of cranking the tower over.

My attempt to improve that hit a dumb mistake and I had to go back to original short term fix, and that ended up barfed up.  It stayed barfed up until after my two week followup checkup and then I created a temporary fix that was better.  It involved putting two bar clamps on the tower to position the halves of the wooden tower clamp.  I wasn’t supposed to be doing lifting or anything like what I did, but these clamps went up on February 12.  At least the tower was more secure. 

With those clamps in place, I was able to re-cut a 2x4 to replace the one you see there (painted white) that those clamps held in position, (well, the clamps along with a couple of lag screws).  It also replaced the one I barfed up the day before the surgery by turning it over one too many times.

That improved pressure treated 2x4 went up on March 9th, the first day I was cleared by the surgeon’s office to lift more than 25 pounds.  

(yes, that does mean Left and Front)

With the temporary fix in place, it was time to work on the permanent fix for cranking over and supporting the tower a whole new way.  As described in that January post, it started out based on designs I had seen researching the Aluma Towers MP-2 (mounting pole). 

First step was building things in the CAD world and I started in the direction mentioned in that January post of moving the tower to other side of the pipe I crank the tower over against, and changing it so the tower cranks over from the top of the pipe (around 7-1/2 feet) instead of the hinge on the base.  After a few weeks of very little progress, I took the approach of emulating the house bracket, but about a foot lower, and instead of mounting the bracket to the house, attaching the mounting bracket to that 4” schedule 40 aluminum pipe.  

The tower is on the right, of course.  Everything else is structural aluminum and stainless steel hardware.  There are two main arms made of 3” aluminum channels with 1-3/4” tall sides.  The very end of the arm is a piece of solid 1x2.5” aluminum bar 10” long.  Those are the last major design change; when I started out there were going to be pieces of channel attached to the tower with U bolts, but then I had to connect two pieces of that channel meeting at a 30 (or 150) degree angle.  How to do that just evaded me until I had the idea to rotate the channel stock pieces a few degrees and just grab the tower legs with straight, solid pieces of metal.

That 1x2-1/2 required some machining; first, the inside width of that channel is a bit under 2.5” and the bar was a bit over, so it needed to be reduced in width by around 0.040” (just over 1/32 inch).  Second, the inside corners of the channel have about a 1/8” radius, and I opted to just cut off the corners, leaving a flat.  It’s hard to read the dimensions in this view, but it says those two arms are each 4 degrees away from the centerline of the pipe to tower. 

You’ll notice there’s no obvious hardware in the drawing joining the channels and the solid bars.  That was done with a couple of 5/16 bolts.  The U-bolts around the tower legs are 3/8”.  It would be rather trivial to enlarge the 5/16” holes, but they seem pretty stable.

The completed assembly.

This has been in place for one week (since April 7, to be exact).  Last week was the windiest in months, probably the windiest since the two tropical storms.  My plan is to approach storms the way I always had until Ian.  Before, I removed two lag bolts to free the tower from the house bracket and the one mounting screw in the concrete slab for the tower leg.  The bolt that tore off a piece of that leg.  Now I’ll remove that same bolt on that one leg, plus two nuts on each U-bolt around the tower legs.  Then the tower gets cranked over and the antennas removed and stowed for the storm.  Once those are secured, I’ll crank the tower back up and fasten it in place so that there’s no wind load on the antennas pushing on the tower.  I get the feeling doing a dry run of this, or a few of them, would be a good idea.

While I feel awkward not having good mechanical analyses of various loads from varying directions on this bracket, it’s exactly as well-documented and analyzed as the original house bracket. 

At least for the moment, the house bracket is still in place, but there is nothing attached to it.  It will probably be taken down once I figure out what I’ll need to repair where it has been mounted since the early 1990s.