Towers

[Troubleshooter]

LOL!!

 

[StrangeBrew]

A simple drain hole in the right spot should take care of standing water.

 

[Captain Kilowatt]

A simple drain hole in the right spot should take care of standing water.

Indeed and without it if you live in an area subject to freezing temperatures you run the risk of having the bottom of the mast split. I have seen some towers with tubular legs build up water and split from freezing. Needless to say having the base legs of a tower or mast split runs a high risk of catastrophic failure. I do not like tubular leg towers for this reason. I prefer either solid legs (HEAVY) or 60 degree angle stock like my Trylon or the AN Wireless series or open channel bead stock like the Delhi series towers. There are no hidden surprises waiting inside the legs in the form of rust either.

 

[Captain Kilowatt]

Let me run this by you to see what you think.

Cut down the existing 2in pipe to a 3ft stub.

Slip a 3in x 10 ft pipe over that and bolt it with 1/2in bolts

Use a 2in x 10ft schedule 80 threaded pipe coupled to a 2in x 10ft schedule 40 threaded pipe and slip it 2 ft inside the 3 inch pipe and bolt it.

This makes 28ft and his eave bracket will support part of the 2in section.

Finally, use a 10ft x 1 1/4 pipe and slip it 2ft in the 2in schedule 40 pipe and bolt it.

This makes 36ft. All pipe will be T1061 aluminum.

I mentioned schedule 40 for one of the 2 inch 10ft sectiond because 1 1/4 maybe to tight to slip in a 2 inch pipe. Also ordering 10ft pipe will be cheaper shipping compared to an oversized rate for a 20ft piece.

Imax antennas are light, the pipe is light and 1/2 bolts are plenty strong enough to hold all this up.

What do you think?

The problem I have with telescoping sections of pipe is the fit. IF one pipe just barely clears the next pipe and there is no wiggle room then fine but most often that is not the case. Bolting the sections can still leave room for the joint to wiggle a bit unless the outer pipe is compressed enough to fit tight which is pretty much impossible when using actual pipe as opposed to thin walled tubing. Waaaaay back when I first started in radio I had a Wilson Shooting Star beam on the end of the house. There was a 22 foot length of 4 inch well casing set in a small concrete base and attached to the eve with a sturdy home made bracket. There is NO need for a large concrete base if the mast is anchored to the house. On the side of this mast at the top were two sleeves made from smaller pipe......2" ID I believe and about 2 inches long. These were welded to the 4 inch mast and had a hole drilled with a nut welded over the hole. Inside these 2" ID sleeves, which were spaced about 3 or 4 feet apart, was a longer pipe of about 15 feet or so IIRC, of 2" OD which was able to slide up and down inside the sleeves and was held in place by inserting and tightening a bolt thru the nuts welded to the sleeves. This simply clamped the smaller pipe and did not pass thru it. This allowed fairly easy raising and lowering the antenna to the rooftop level to work on it although with the heavy pipe and large antenna it was quite heavy. It also took out any slop in the fitting of the two pipe sizes as it was clamped TIGHT. It withstood many nor'easter storms and a hurricane or two with an issue. I was 14-15 at the time and by father was a welder so it was done right and worked well. Using poipe is fine as long as it is not thin walled swaged tubing type.

 

[fourstringburn]

The problem I have with telescoping sections of pipe is the fit. IF one pipe just barely clears the next pipe and there is no wiggle room then fine but most often that is not the case. Bolting the sections can still leave room for the joint to wiggle a bit unless the outer pipe is compressed enough to fit tight which is pretty much impossible when using actual pipe as opposed to thin walled tubing. Waaaaay back when I first started in radio I had a Wilson Shooting Star beam on the end of the house. There was a 22 foot length of 4 inch well casing set in a small concrete base and attached to the eve with a sturdy home made bracket. There is NO need for a large concrete base if the mast is anchored to the house. On the side of this mast at the top were two sleeves made from smaller pipe......2" ID I believe and about 2 inches long. These were welded to the 4 inch mast and had a hole drilled with a nut welded over the hole. Inside these 2" ID sleeves, which were spaced about 3 or 4 feet apart, was a longer pipe of about 15 feet or so IIRC, of 2" OD which was able to slide up and down inside the sleeves and was held in place by inserting and tightening a bolt thru the nuts welded to the sleeves. This simply clamped the smaller pipe and did not pass thru it. This allowed fairly easy raising and lowering the antenna to the rooftop level to work on it although with the heavy pipe and large antenna it was quite heavy. It also took out any slop in the fitting of the two pipe sizes as it was clamped TIGHT. It withstood many nor'easter storms and a hurricane or two with an issue. I was 14-15 at the time and by father was a welder so it was done right and worked well. Using poipe is fine as long as it is not thin walled swaged tubing type.

I've made telescoping mast before and have one now for 10 meter Moxon beam. Those sections of pipe really don't leave much wiggle room and when bolted, they are solid enough for light antennas.

Those Rohn 18ft, push up poles are based off the same principal.

Thanks for the response.

 

[Captain Kilowatt]

I'm just used to being in a high wind area where the wind constantly buffets around from all directions due to valleys and hills. I'm also used to having heavier antennas so I tend to look at any possible point of failure. I did reinforce my mast by sleeving it with another pipe that had a very close fit.....enough so that I had to drive it in with a sledge hammer. I then drilled and tapped holes for a 3/8 shoulder bolt in the inner pipe with 3/8 clearance holes in the outer pipe. I tightened stainless bolts until the shoulders jammed into the outer hole then cut them off flush and ground them flush. After painting you had to look hard to find them. This locked both pieces together. I have see inner pieces work loose after fkexing in wind and actually slide down. I could not have an6 bolt heads exposed due to the need for the mast to be jacked up inside thrust bearings.

 

[338_MtRushmore]

I agree, with removing the slop from the joints. In post 12 I mentioned using set bolts for this reason. I really don't even like the idea of a through bolt just because it adds more stress risers and potential for failure. I would personally use 3 to 4 set bolts per connection, and add a single 5/16" through bolt for a safety backup.

I just used a single 1/2" set bolt on my 25' push up. 50mph gusts today without issue.

 

[Captain Kilowatt]

My issue is eventual elongation of the holes due to movement. This leads to more movement and more wear etc. It may take YEARS to happen but the thinner the wall the faster it will happen and all 5oo often people underestimate the wind and go cheap with thin walled pipe. When I take on a job of installing antennas it is a job I only want to do once. Call it overkill but I have yet to have an installation fail for ANY reason. I personally still prefer a decent freestanding tower.

 

[Troubleshooter]

I agree, with removing the slop from the joints. In post 12 I mentioned using set bolts for this reason. I really don't even like the idea of a through bolt just because it adds more stress risers and potential for failure. I would personally use 3 to 4 set bolts per connection, and add a single 5/16" through bolt for a safety backup.

I just used a single 1/2" set bolt on my 25' push up. 50mph gusts today without issue.
View attachment 20789

Will do on the bolts to use.. Thanks for the heads up.. My friend does contruction and does excellent work... I have had many things done to my house and he does stuff the right way, thats why I wanted him on the project..