A question for our steelmeisters

[dragonfly]

I built a small experimental purple martin house with three deep compartments for a test trial, and I need to know something about steel poles. Imagine a tall bluebird nestbox with three compartments. Total outside dimensions are 30" tall by 8 1/2" wide, and 7" deep. It's made of western cedar and I estimate the total weight is around 10 pounds.
Anyway, would rigid electircal conduit be suitable to use for a mounting post? (1 1/2" or 1/1 4" diameter) From what I understand, the tensile strength is great, but what is the downfall of this type of steel for holding a tall narrow wood box about 10 feet up?
Anyone have a good idea?

[Fuzzy]

It will blow around a bit with wind. Not that you have any wind in Texas. Just remember your basic physics. Every foot pound applied at the top will be multiplied by 10x-12x -- The pole acts as a lever arm that is 10-12ft long. At some point you can achieve enough force to bend the pole -- That is how they bend conduit.

[standman]

Would filling it with concrete help? I know it would make it a lot heavier, but probably would add substantially to the strength. Another option, insert one pipe inside the other. Would allow some flexibility, but stiffen the assembly as well. That being said, most of the boxes in our area are mounted on conduit or water-well pipe. Don't know how the rigidities compare.

[dragonfly]

Thanks guys. I plan to telescope another piece down into the base pipe for raising and lowering the house. Where would I find out how much force is required to bend the heavy conduit? I'm not concerned about our average weather, but about late spring storms where we often have winds in the 40-60 mph range in gusts.

[Bodo]

Conduit would be OK if you went with the larger sizes (2" or larger). I would still be worried about the strength of it. How high do you want to go?

[dragonfly]

Conduit would be OK if you went with the larger sizes (2" or larger). I would still be worried about the strength of it. How high do you want to go?

The total height would be almost 13 feet. So is the heavy conduit structurally weak? Is there something more suitable that I can by at HD or Lowe's?

[Hambone]

Here ya go DF. This is their Weatherford location. They will have everything you need. I would use something like 2 3/8 pipe. Should be +/- $1.50 a foot. And they will cut it to length for you.

American Pipe & Steel
(817) 594-0772

[Bodo]

The walls aren't very thick on the conduit. If if get's creased by a lawn mower or something, I could see it ending badly.

[dragonfly]

The walls aren't very thick on the conduit. If if get's creased by a lawn mower or something, I could see it ending badly.

I'm talking about the rigid conduit- the one with thick walls. The thin stuff is EMT. The rigid wall has threaded ends.

[Fuzzy]

That is why TV antennas, Telephone poles, and boat masts have 3 guy wires. The point where they join the mast becomes the axis for bending. If they join at 10ft then you only have 3 ft of leverage above that point. Only a hurricane or F4 tornado would hurt it then.

[MapMan]

Look up schedule 40 piping. That will handle the weight and forces.

http://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html


MM

I'd use threaded gas piping and you could attach it the base of the house with a threaded flange. Been there, done that, and it works.

[dragonfly]

Thanks for the link MM:)
That's the kind of information I need.

I thought about threaded gas pipe, but I've never seen any besides the really small stuff.

[dragonfly]

That is why TV antennas, Telephone poles, and boat masts have 3 guy wires. The point where they join the mast becomes the axis for bending. If they join at 10ft then you only have 3 ft of leverage above that point. Only a hurricane or F4 tornado would hurt it then.

That's something to consider, I suppose. Is there a specific angle that guy wires need to be attached at?

[Fuzzy]

"Is there a specific angle that guy wires need to be attached at? "

Nope... They just need to be anchored in an approximate triangle.

Forgot to mention that I have a hop (beer hops) trellis in my back yard. It is 17ft tall made out of 1 inch schedule 40 PVC. It is anchored with 1/8 in nylon twine and stands
up to 30-40 mph winds. It supports a lot more than your 10 lbs bird house.

Fuzzy

[Eaglerock]

Need something like this DF?

http://www.sk-mfg.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=P

[dragonfly]

Thanks ER. I have a Tri-tel pole, but it's not strong enough for the kind of house I have. It's pretty thin wall, and it's great that it telescopes, but it doesn't hold up well in high winds.

Since I already had the rigid conduit, I've decided to go ahead and use it, but I bought a 1 1/2" 11g round steel tube to telescope all the way down into it, and the top five feet will be adjustable so that I can lower it in bad storms. I think this will work out. I can get the height I need, and I think the extra "skeleton" inside the conduit will give it enough strength for a 10 # house.

[TwT]

depending on the size and weight of the bird house even schedule Forty-4" pipe will flex some if the wind gets high but not much ( thats a 20 foot stick), if I was going to build a good size martin house on a pole that is what I would pick, and plant it about 3 feet down with concrete around it.

[dragonfly]

if I was going to build a good size martin house on a pole that is what I would pick, and plant it about 3 feet down with concrete around it.

Gee whiz, I bet that would still be standing after a tornado and an earthquake occured at the same time!:eek::)

[Hambone]

Since I already had the rigid conduit, I've decided to go ahead and use it, but I bought a 1 1/2" 11g round steel tube to telescope all the way down into it, and the top five feet will be adjustable so that I can lower it in bad storms. I think this will work out. I can get the height I need, and I think the extra "skeleton" inside the conduit will give it enough strength for a 10 # house.

I was at the local lumber yard today. I passed by the conduit. Had to turn around and take a look for ya. I don't think there would be any reason what you have would not work. Do you plan to concrete the post in?

[dragonfly]

I was at the local lumber yard today. I passed by the conduit. Had to turn around and take a look for ya. I don't think there would be any reason what you have would not work. Do you plan to concrete the post in?

It's already in concrete.:D When I get a project in my brain, it gets done pronto. Today, I cut the 11g round pole, primed and painted it, and it will be ready to go in tomorrow. It fits well inside the rigid conduit, with just a tiny bit of slack, and will serve as a skeletal support. I finished the house yesterday. I just have to mount it onto the top section of pole, and put it up.
Thanks for checking for me Derek.:)