View Full Version : Tubular steel tower construction help.
11-18-2008, 05:49 PM
I would like to construct my own small tower made of either round steel or square steel stock. Does anyone have any past experience with this concept? It's not going to be taller than 50'. I'm envisioning a 2-section round tube about 3-1/2" diameter about 45' high. I have a large concrete base w/ 3 angle irons sticking upwards available next to a building. The building has a brace already bolted thru at 12' up. It was the site of a former tower 20yrs. ago. Weight isn't a problem as I have a backhoe easily available to assist in lifting my structure. Welding equipment is here as well.
I would appreciate any assistance you may offer. Tnx. Bob N3JQD
Someone a while back asked that same question here on QRZ - boy did he get LOTS of answers - ALL saying "Don't do it"!!! or some version of that answer.
There are several issues with building your own tower - cost for the main one. You mention a 3-1/2" round tube - when I think of a tower I tend to think of something more like the Rohn towers. In this area used Rohn towers can usually be had for $20 or a section - that's only $100 for a 50 ft tower.
With that being said, since you have the equip, most likely you have more experience in fab'ing metal than half the answers you will get here on QRZ. YOU know your own level of knowledge, welding skills, etc MUCH better than any of us know.
Due to the extreme level of litigation in this country, most folks are leery of offering advice on how to build a tower in a public venue like this. Who knows what will come back to haunt them yrs down the road - some hot shot crook (lawyer) might well find the suggestions and add that person to a court case. Remember: common sense and justice have NO place in today's court system.
rant mode off:
Good luck and do let us know how it works out and your course of action.
73 de Ken H.
11-18-2008, 07:44 PM
Thanx Ken. I'm more of the "let's do it" and watch what happens kinda guy when it comes to legal 'stuff'. My brother is a lawyer and in close proximity to my work QTH. PA. just adopted the PRB-1 style law in Oct. 08.
Yeah, I've seen Rohn towers for sale, but, all have been many states away. The ones that have pics attached looked a bit rough also. I'm going to continue my search and await some replies herein. Thanks again. Bob N3JQD
I'd say it can be done if you build it like Rohn 80 with X bracing. You could Z Brace it with solid round stock but you better be a real good welder to do this to the slightest wind load or twist would cause a major collapse. Gravity + Galvanized Steel = Not Pretty (Death & Destruction)
Your best bet is to look at Rohn 45 to 80 real close, draft up and idea and have Structural Engineer go over your idea. Lot of calculations to take into account when it comes to vertical load, wind load, sheer points, steel grade, ect.
What are you thinking about doing for weather proofing the steel after you get done grinding and welding on it? Cold Galv paint doesn't last very long and just delays the oxidation process.
This is doable as long as it is done right, other than that it may be way too dangerous and risky to attempt to put up a home brew tower.
11-20-2008, 12:44 PM
OK. Thanx for the response. Yes, I'm taking a very cautious approach. This township is very strict and would levy an immediate Cease and Desist order. They require an engineering report, so that will probably preclude my homebrew design since it wouldn't have an engineer building it. I have a ham that has built one very succesfully and he sent me photos. Well, I guess that I'll continue my search for a manufacturered tower. 73 Bob N3JQD
11-20-2008, 03:59 PM
Slap a free (but filtered and bandwidth restricted) wireless access point halfway up your tower, hang a couple of endangered species bird houses a little farther up, and watch a lot of your neighbor-generated resistance go away ;)
If there's something in it for Mrs. Smith next door, she's much less apt to start wagging her finger :D
I Built a 40 foot tubular crank up tower for my motor home. The reason I built it was that a custom length was needed on my RV to comply with maximum vehicle height limits.
For a home installation, I would recommend purchasing a good used one for safety, time and cost considerations.
If you wish to build one for the experience, and do not want it to be a "bad" experience, then I have some suggestions.
1. Do some research on the PSI rating of the pipe used on commercial towers and follow their guidelines. Registered Professional Engineers (PE) have reviewed their plans to determine structural integrity. Use spray galvanizing on all of your welds when finished.
2. Rectangular pipe will more easily prevent telescoping tower section from rotating independently. It is also more expensive and difficult to find. You may want to devise a way to prevent independent rotation of round concentric tubing.
3. Use good steel pulleys. Most available pulleys found in hardware stores today are cast pot metal (junk) which are not very strong and you really cannot weld them anyway. Marine stores near you may have rust resistant steel pulleys that can be reliably welded or you could find them on the internet.
4. The cable material is very important. Buy it from a tower manufacture unless you can find a GOOD source. Box stores typically sell cable that is more cost effective, but lacks the galvanized plating to prevent rust from degrading the cable with time. Again follow the lead from the commercial tower people. The cable holds the entire weight of your tower, antennas, rotor and coax.
5. Which winch? ALL towers that I have seen use "Fulton." But wait there is more............. Most Fulton winches are rated for pulling horizontally and (a few) others are rated for "lifting." You only want the lifting type. They are built to handle a vertical load and have a braking system as opposed to the ratchet type that is often used on a horizontal winch for boat trailers. Boat trailer winches typically have a smaller diameter drum which stresses the cable more than a larger wind up drum and will causing premature cable fatigue. My 72 foot towers use a Fulton model K1550, 1500 lb load winch.
6. How is your welding? Commercial tower manufactures use "certified" welders. The welded pulleys carry the full weight just like the cable. The base mounting is a welded assembly and because of the thickness would require a deeper penetration. A bad weld could mean disaster.
7. Footing. Again, you need to follow the plans drawn by a PE. They are available from tower companies or on the internet. My towers use a 5' x 5' x 8' deep cement foundation that has a "shark cage" of rebar inside. The 4' long x 1 1/8" bolts that the mounting plate attaches to are suspended in the hole before the cement is poured. The cement must be a high PSI rating, not the normal stuff used for sidewalks. Use a six or seven sack mix.