[Linda so]

Hello,

We are retiring to the mountains of northern New Mexico. I want to create a flag pole and set it and do it correctly the first time in this area at 6,500 feet of elevation and quite high winds in the Rocky mountains. I have done the physics math for a foundation and find a footing of 7 foot nine inches would be needed and have already formulated how this will be done to resist those high breezes and counteract the torque forces trying to twist the flagpole out of the ground.

I've built a hinged base of 2 pieces of 8 x 8 x 1/2" steel and have them connected with a very high grade industrial 3/4 inch bolt. What I am not familiar with is pipe. I wish to learn what sizes will nest together so I can build a 52 foot tall flagpole of 3 pieces of 20 foot long pipe with two- four foot overlaps, so that it is strong, straight and true. Decades ago before going to college I was a structural Ironworker and was a certified welder. Fabrication and erection should pose no problems, but doing this correctly so the flagpole is rigid in up to 100 MPH winds and is correctly welded in sequence to that it stays straight in assembly is extremely important to me. I know about schedule 40 and schedule 80 pipe and need to know which ones to use and which dimensions. I have been told that 3 1/2"-3"-2 1/2" pipe should nest together and fit. I do not like SHOULD!
Is there any expertise out there that can provide me with the correct dimensions, the correct specifications and the correct procedures to complete this project and make a permanent lasting pole for the MIL-Spec flags I will have to be using on the elevated , windy terrain?

Thank you for your attention in this matter,

Gene

[uncleflag]

Hi Linda SO... that's quite the project you are taking on. Is there a reason why you don't just buy a 50 ft flag pole instead of making your own? They are not as much as you'd think, definitely less headache and have guaranteed wind loads. Concord is out of Texas and they make some of the best aluminum poles in the world. I have a 50ft continental... and I love it! It has a 127 mph wind load which should be more then enough for what you are doing. We are a dealer for Concord and sell the 50ft for around $2700 plus shipping. Of course I give discounts for fellow flag site patriots.

[Maltelec]

have them connected with a very high grade industrial 3/4 inch bolt

1st thing I would say is what do you class as high-grade? 8.8, 10.9?

You'd need 8.8 at least and make sure the nut is the same.

2nd of all, it would sound like you have just used 1 of them, assuming this is on the un-hinged side.

This would put a lot of stress on the hinge. All the towers I deal with never use the hinge to hold the mast up, with the exception of a small tower (6 meters which is 18 foot) which uses a 1" diameter steel pin as the hinge.

The best way to bolt the two parts together is to use 4 bolts on each corner and do it in a way that with the tower/pole bolted upright the weight is taken off the hinge. Otherwise you'll find the hinge will allow the pole to shake a bit and this will eventually break the hinge.

As for the pole its self, I would be tempted by a light hollow steel (galvonised) pole about 4" diameter. Possibly 3/16th of an inch thick (like a street light).

You don't want it too heavy that it bends under its own weight, you don't want it too light that it bends with the drag caused by the flag. You also want to raise and lower it which is a point I will come to a bit later.

So if you went with my choice, 4" pipe 3/16th wall thickness, you could weld it together at the joints which if done properly will be more then strong enough, you could weld it to the base plate you have made, and you can weld on the pulleys and other bits you need for a flag.

To raise and lower a 50 foot 4" diameter 3/16" steel pole, which will weigh around 200 lb at a guess, is not going to be easy.

All the Camera towers I use come either fixed (a right pain to use) or hinged. The hinged ones generally hinge about 4 foot up and you attach a specially made winch to raise and lower the mast under your control.

This is the type of smaller CCTV pole I work on:



It is made of very thick metal for its size both for rigidity (nothing worse than a wobbely camera in the wind) and also for security. Both things which arn't too important for you.

You can see the size of the hinge though, a great big steel pin. These type of poles generally keep the weight on the large hinge and use two M16 bolts at the bottom to ensure the bottom doesn't move.

Some alternative materials would be wood, fibre glass, plastic, carbon fibre.

I am a metal person and have no experiance in anything else so if it were me, I'd go with what I know.

[Linda so]

Thank you Maltalec,

I appreciate each and every bit of information you have shared with me. Many decades ago before I went to college I was a structural Ironworker with welding certification is three different states. I wouldn't consider anything else other than steel for the flagpole.

The weight of the finished pole is a lesser concern since there are three different colleges in the small town I am retiring to. Recruiting enough strong bodies for positioning shouldn't be that difficult.

With regard to my base plate, the 3/4 bolt at its fulcrum at the base of the device should be adequate and is HARD. There is a 1 inch bolt that attaches the two plates together when the mast is raised. Your insight about movement after the raising will allow me to go the next step and tack weld the two plates on the non hinged ( bolted) side together. Since the bottom plate will be welded to the rebar in the footing that will go down 7' 4" this base should be extremely rigid, with your insight. 4 inch pipe would fit nicely on the base.

I am lucky that there is a 4 x 4 rigid steel post, ten feet tall, set into a concrete slab in direct line with where the flag pole is going to be set. I am making a snatch block assembly that will be temporarily bolted to the top of this post. A cable will be run through the block and attached to the flag pole at ten feet. Thus the cable, when attached to a 4 wheel drive rig, or heavier tractor will simply pull the pole into place after the two pieces of the base plate are attached via the bolt to each other.

I've still not located the pipe for this project. I realize that it will probably be much easier to locate it in Seattle and take it along with a lot of my other stuff by trailer to northern New Mexico, than try to locate it at a good price there.

Thank you for your insight and I wish you the best 2009 possible.

Gene So

[Linda so]

Hello Folks,

Things I have learned in the interim about making a flagpole. Schedule 40 pipe is heavy duty and allow you to build a significantly tall flagpole. The dimensions allow a 3 inch pipe- 2 1/2" and also a 2" pipe to nest inside each other and with careful welding, the finished mast will be straight. With the heavier wall thickness of these pipes they will need to be set into each other only 18". 1/2" holes can be drilled near the top of the larger pipe and at the 18" level; they should be staggered. Then the smaller pipe is fed into place, measured for straightness then welded in a gradual process so the finished product is square, plumb and true. Repeat the process for as many length as you wish.
The price of scrap steel has gone from .45 cents a pound to $1.45 in just a year of craziness. its starting to go back down , but just a little. I was able, on Craigs List, to find the three nesting pipes I wanted for my pole from a retired steel fabricator for .45 cents a pound and shall be taking them with me to New Mexico because I simply will not relish running around that state and paying a retail price for the steel.

Now, the next step logically is located excellent hardware for raising and lowering the flags. I have been told that the top most pulley is crucial and realize when it needs repair the only way to do that is lower the whole flagpole. So, I want to attach the best, long lasting pulley available for the money; also the lanyard for raising the flags.

Thank you for your attention in this matter,

Gene So