I never could find any of those expanding plugs shown in those instructions of the proper size. I eventually ended up with delrin plugs, and I am very happy with them. Here's how I put them together...
Cut 2" of delrin rod that matches the tubing OD. Chuck into lathe and turn all but about a 1/2" shoulder down to press-fit the ID. Drill 5/16" hole for a 3/8" x 2.5" hardened machine bolt (I've been using grade 8). Thread a nut all the way up the bolt and put a Fender washer that matches the tubing OD under that (or you can grind off an oversize washer to match after assembly). Place plug, washer, nut, and bolt together in a bench vice and apply a little teflon lube to threads. Gradually maintain compression on assembly with the vice while threading in the bolt with a wrench - you will have to hold the plug from spinning with a pipe wrench. Thread bolt all the way in (assuming about 1" of bolt is threaded). Grind off bolt head until it is rounded smooth with the shaft of the bolt (cooling frequently with water).
Clean the interior surface of pole tubing and rough-up with coarse grit. Now apply Plumbers Goop around the plug and press it into the pole, up to the shoulder. Let cure for a few days before use.
Another thing I did different… Instead of using shim stock for a close fit on the coupler tubing, I cleaned and roughed the tubing surfaces and gave the inner tubing a layer of epoxied glass. Obviously, I didn’t get the sizes really close to begin with. Anyway - after glassing the inner tube, I used course sand paper (no oxide grit!) to smooth the glass surface to a press-fit in the outer tube and then epoxied it in place. I got a nice smooth and snug coupling this way and it seems to be holding up well.
Alu is certainly a better conductor I’d far prefer to use a dry wooden pole to poke the 120/240 volt cables that bring power into my house or even the 480 volt cables feeding comercial and industrial sites. I would NOT poke those cables with aluminum nor a damp wooden pole.
I’d be less inclined to do that with the 13800 volt local transmission lines at the top of the poles running down the street. Twelve feet is too close to those lines for me no matter what the pole was made of. Take a look at the protective gear linemen wear.
I’m told that lightning runs to the millions of volts. It surely jumps across pretty great distances of air. If a charge builds up around you, any sharp point will be the most likely place for a discharge.
With voltages in the millions I’d not care to wave a damp wooden pole around any more than I would aluminum.
I think Tommy has the right idea And the qualifications as well, methinks.
In a lightning storm, I think that conductivity is pretty irrelevant. Whether the pole is made of aluminum, wood, fiberglass or cat crap, how conductive it is for current does not matter. What matters is its capacity to attract a strike. The name of the game here is to not be the highest point on the landscape, and also not be too close to the highest point.
So I suppose in a lightning storm, I’ll be shipping either of my pole to the bottom of the boat, and kneeling with a paddle in hand to get to shore.
In poling, the pole gets caught between unseen rocks. An aluminum pole is relatively hard. A carbon fiber pole is more easily damaged. Once a carbon pole is nicked, if the nick isn’t repaired, it can lead to sudden, catastrophic failure.
If there were a way to prevent such damage, carbon fiber poles would look real good. But as owner of WW paddles with carbon fiber shafts, I already have to worry about nicks. I don’t need 12 feet worth of possibilities.
I think titanium is an interesting possibility for poling, but I don’t know what wall thickness to specify, and where to find a supplier.
Optimum weight I find that my lightest aluminum pole is sometimes not heavy enough at ~3lbs. In deeper pushy water, I will switch to one of my poles that weighs closer to ~ 5lbs, and it gets to the bottom plant much easier. I’m not sure I would ever be interested in a pole weighing less than ~3lbs unless there was some way to keep it from bouncing when planted with the force it takes to overcome current - but I don’t race, and that may be different.