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The Rotating Beacon AKA Project Humpty Dumpty

Robert Roswick is a grey-haired tinkerer born, raised and living in Bismarck, North Dakota.

Why is the rotating beacon down... Oh-oh!

Why is the rotating beacon down... Oh-oh!

KABOOM!

December 10: They were servicing the rotating beacon at the Mandan Airport when the lowing cable snapped. KABOOM! The beacon went all Humpty Dumpty on Lindsay, the airport manager. A month, yes, a month later I see the mess and go check it out.

Ouch!

Ouch!

I ask Lindsay if I can have the mess. She gives me thumbs up because it is all going in the dumpster anyway. I back up my truck and haul, what I can find in the snow, away.

Once in the hanger, I set up what looks like an NTSB investigation. I lay the puzzle out on the floor and do an inventory. Yes, it looks like I have all the pieces of the housing but some of the hardware is missing, hinges and latches that... well… exploded.

The next thing I do is take a bunch of measurements to try to figure out how big this thing is. The one thing I should have done was weigh it.

rotating-beacon-or-humpty-dumpty

The process.

With a couple of drawings and a bunch of measurements, I headed home and loaded up the software program Fusion 360, which is provided free of charge to hobbyists like me. In the software program, I made a drawing of the box and the light, by modeling it. Now you can see how big it is. I can get measurements. As the light rotates it sweeps a path through space and I can check clearances for mounting purposes. I can tell you how many times I have done something like this only to find it is mounted too close to the wall or so high the device hits the ceiling or some other obstacle. Modeling is a good idea and for this, Fusion 360 is a great resource.

Fusion 360

Fusion 360

The one thing I didn't add was the hinges that are molded into the magnesium housing. This usually is not a big deal, but they stick out. Had I not remembered that fact, the bracket I made to hold it would have been too short and it would have ended up hitting the wall.

Whenever you do a project like this you'll always forget a few of the details, It is important to always give yourself a little extra room here and there.

rotating-beacon-or-humpty-dumpty

Damage Report


The light was made up of 5 parts and with the base, that makes six. Two lenses (which I was shocked to see were not broken), two reflector housings, and single center ring that held everything together. The lenses were hinged to the reflector housings which were hinged to the center circle. But this second set of hinges was torn off.

The hinges explode.

The hinges explode.

This all sat on top of the box then held the motor and the shaft to make it all rotate around. The base of this box had been torn loose from its mount. Two of the bolts held while the other two were ripped out of the bottom of the box. The bottom had gouges where the bolts were ripped right out of the box.

The bolts torn loose.

The bolts torn loose.

Fortunately, after you repair a box like this, gravity tends to pull it towards the ground so the fact that the bolt holes were ripped out from below is very helpful.

Not only was it truly amazing the lenses did not fracture, but the rotational apparatus was also still intact. It was neither bent nor bound up. The belts survived the crash. The electronics held firm.

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Wow! The guts are intact....with a couple of inches of snow.

Wow! The guts are intact....with a couple of inches of snow.

This means is that this box hit the ground and the shaft that holds the light fixture did not bend but the light fixture blew up. So for some reason, the light fixture took all the shock and the shaft was spared.

rotating-beacon-or-humpty-dumpty

After modeling it on the computer I determined that I need to make some jigs to hold all the pieces together. I planned on using epoxy to put Humpty back together again, but I needed something to hold the pieces in place while the epoxy hardened over 24 hours.

Designing jigs in V-carve

Designing jigs in V-carve

Making Jigs

I went to my computer and loaded V-carve, a CAD/CAM package. I designed some brackets to hold the whole thing followed up by a trip to the router table to cut these parts out. Once the parts were cut out, I was able to assemble them and create a cradle to hold the pieces while I glue them together.

A jig to hold the center ring.

A jig to hold the center ring.

Once the design was complete, I went to the CNC router table to cut these parts. With the parts were cut out, I was able to assemble them and create a cradle to hold the pieces while I glue them together.

...and more jigs.

...and more jigs.

The interesting thing about magnesium is that it doesn't like to bend. It tends to break, like an egg.

The bad thing about magnesium is before it fractures it bends a little bit so all the pieces had clean fractured lines. While all the fraction lines went back together, unfortunately, the pieces had warped. They were permanently bent next to the fracture sites. This made putting the pieces back together more interesting.
I happened to have some Scotch-Weld Epoxy so I'd give that a try.

One of the lenses just had one hinge ripped off. I thought I'd start with that. I gobbed both parts with a generous amount of epoxy and stuck them back together. Unfortunately, it takes the epoxy 12 hours to harden. Furthermore, this only happens at 74゚F. It is minus ten outside and my shop is only 40-60゚F. So the only way this was going to get this done is by turning up the heat and putting a lot of clamps on the piece to hold it in position. This would only take some clothespins for the first reflector housing. I lined up the holes with a long drill bit but it was too heavy and pulled the piece out of its mount. I removed it. Once dry, it was unfortunately crooked. I thought, “This is going to take to grind this down to a point where I can use it.” (I was right!)

My first trial - my first boo boo.

My first trial - my first boo boo.

Two Part Epoxy

For the other reflector housing, I needed vice grips, a wood clamp, two C-clamps, two clothespins, and an extra-long wing bit that I should have used on the first housing. Despite all that, it dried and hardened the hinge was firmly attached.

The crackup.

The crackup.

This reflector was so bent that the pieces didn't even go back together so I stood on it, jumped on it, hit it with a mallet, hit it with a dead blow hammer, and pounded it back into shape. This was not without consequence. I broke off 2 more pieces before I was done. I tried to just consider gluing in one piece at a time but unfortunately, the only way all these pieces fit is when they're all put in simultaneously.

So back to the 3-D model to check some measurements. I was able to hand cut some forms to hold the inside of the reflectors in position. I glued 4 parts in place. I was also able to run a rod between the 2 hinge points to make sure that they were in alignment. This was extremely helpful when it came time to assemble. I put all the parts in my jig and gobbed everything up with epoxy. The pieces ended in their respective positions. As I got one in place another fell out. As I put that in place the first piece fell out. “All the King’s horses and king’s men, couldn’t put Humpty Dumpty together again.” I then realize that multiple layers of duct tape on the outside will hold the pieces in place until such time I can get the jigs and everything into position. God bless duct tape. All in all, the result was fairly favorable. The issue was I epoxied the jig to the reflector housing … oopsie. It couldn't remain so now my task at hand was to carve out the jig. With some diligence and a hammer to chisel is able to get all the wood out of the way.


Now the hardest part was the center ring. It was tough due to so many pieces. Three off the hinges had pulled free of the ring and the ring was left in 5 pieces. I felt that this would be totally unmanageable to glue at once so I put 2 of the pieces in the jig and glued them together and then added another piece to that. To those, I added others. Now is at the point where the last 2 pieces would complete the ring so I put everything in the jig and glued ‘er up.

Humpty Dumpty alright!

Humpty Dumpty alright!

The hinges were left on the counter. Given it fact that the hinge pieces no longer fit, I had to grind them down to slip into the allotted space available. When this was done, those pieces were glued and held in place with duct tape and a rod that went from one hinge bracket to the other. That was my best effort and had I done all the pieces like that I would have been saved a lot of headaches, but this is trial-and-error after all. I veered mostly to the error side of the leger.
So now that these pieces fit together, the first reflector housing was an abomination. It looked good, but the geometry was all wrong. I went after that with a grinder for over an hour before I could get it to the point where it would even sit on the center ring. The holes in the hinges didn't lineup at all. I can deal with that. What you know at the end of a project always surpasses what you know at the start. All the components would actually fit without a whole lot of fuss had I done a better job of lining up the hinge on the first part.

Perfectly round? No so much.

Perfectly round? No so much.

Next, I filled in all the gaps and dimples with more epoxy. 24 hours to dry and a day later I smoothed the surface out with my sanding disk. It turned out much better than I anticipated.

... and mor epoxy.

... and mor epoxy.

The last bit on the light housing was to drill out some new holes for the hinges. So I took some time and painted the housing. Spray paint is in short supply in the city but fortunately, the local hardware store had everything I could want.

Looking better.

Looking better.

Safety Orange is the color of the day and they had multiple cans of it on the shelf. When I sprayed it, it matched almost perfectly.

Safety Orange.

Safety Orange.

The Mount

With the housing's looking pretty decent I could focus my attention on making a mount for this pig. I wanted to mount this on the wall so I went off to Paulkie Steel and bought some angle iron. The wall has a beam on it that's 9 2x4’s wide yet it totals 14" wide with adhesives etc. The light is 16" wide so I'm going to have to make a bracket that attaches to a 14" column but spreads out to catch the base of the rotating Beacon. With a little bit of thought, I was able to come up with a design that worked well.

Bracket mount - getting away from the wall.

Bracket mount - getting away from the wall.

I precut the holes to attach them to the wall. I precut the holes to attach the Beacon to the mount. I made square holes to attached the pieces together, this allowed me to use stove bolts which make for a nice appearance when you're done. This took a day to do the side frame and another day to make and fabricate the bracket. The results were good so I painted up the bracket in safety Orange and it matched the beacon beautifully.

I've got the angle.

I've got the angle.

Mounting it in the hanger.

My last task was to drill new holes for the hinges. This was miserable. The hinges were over an inch thick and made of solid magnesium. I had no leverage to get the drill bit through the material. Yet when you add the appropriate amount of cursing, things seem to get done. With the holes done and everything in place, I hit all the parts with some touch-up Safety Orange. Then I went into my office to watch High Noon with Gary Cooper while the paint dried. Once the sheriff had saved the town without the help of any of its citizens, I grabbed all my things and headed to the airport to mount the bracket.

Trips to the airport are always the same. I get out there and I work until I run out of some critical element, part, or supply. Not to be disappointed, as soon as I got there I realized they forgot the bolts required to put the bracket together. No surprise. I started with mounting the rack to the wall and got that ready to continue with the brackets. I attached all the hardware that I had, then headed home. After a tasty dinner, I headed back out to the airport and completed the brackets. Now is the time to start mounting the light. As I mentioned before I wish I would have weighed the parts because pushing 50 pounds of beacon casing 12' in the air can be treacherous. I got the beacon’s base up and bolted in place and then I started to assemble the top. The first thing was the rain shield followed by the center ring without much difficulty. So much for the low work, now everything is at the extent of my reach. I had to hang the reflector housings which were rather heavy with the new hinge holes that I had created. I stretch as high as I can reach to drop in the first pin. Surprisingly, nothing hit the floor. I held up the reflectors and dropped in the second pin into the hinge to hold it in place. Once that was completed things were stable.


I finished up “reflector A” followed by “reflector B”. Next was to wire the 2 reflectors together. In my 1st go around, the wire nuts that I brought were too small. The bigger ones I brought were just barely big enough but we did get it wired together. Did I mention another trip home between the small night wire nuts and the large wire nuts? I installed the two 200 watt bulbs I had initially bought, but they were too proud of the hole and didn't fit well. I ran to the hardware store and picked up some smaller bulbs. I wanted some clear bulbs with a vertical filament but regular bulbs just aren't all that available anymore. I purchase some LED bulbs with a clear lens. They seem to fit just fine. With bulbs in place, I then started to attach the lenses. Now I am at the limit of my reach holding a lens up above my head and reaching on my tiptoes on top of the ladder. I was able to drop one pin in place followed by a second pin. Wow, the lens cover was in place and I was still alive. The most harrowing part of this process was the fact that I had to reach up and put a wrench on top of the bolts to tighten up the nuts. This required a reach that was even beyond the point where I dropped the nuts in place.

Let us hang it on the wall.

Let us hang it on the wall.

With all that being done it was time to power things up. I dragged an extension cord up the ladder and wrapped it to the bracket. With a live cord, I plugged everything in. The lights came on immediately and the beacon started to rotate as the man yelled BINGO!

While it is not waterproof nor ready for the elements, it will make a nice display in the hanger. Furthermore, the flies in the hanger will need to pay more attention to the left traffic pattern.

Project Humpty Dumpty came to a successful conclusion.

Bob

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