: Okay, so I've run into a small problem. Nothing insurmountable, but it might
: add an unwanted 5 or 10 pounds to my folding Greenland kayak.

: Got 40 lbs. of scrap aluminum tubing from the local recycler's. It used to be
: a Ham radio antenna. Big ol' cast aluminum mounting blocks in the center
: of each tube. Got rid of the aluminum blocks, but there were wooden dowels
: inside the tubing to keep the set screws from crushing the tubing...

Shawn... I make a lot of ham radio antennas... I have no earthly idea why the elements of the antenna would have mounting blocks every 5 feet.... in the center of an element, yes, but along the length... wierd!

: No idea how to get the wood out of the center. There's 3' chunk in the middle
: of every 5' stick o' tubing. I tried driving it out with a piece of steel
: rod. No move.

If there is a 3' chunk inside each 5'piece, it is there not just to hold a set screw but for additional strength. It is likely glued in position. If it does not move at all, it won't.

: Tried heating the tube with a propane torch. Maybe expand it. Drove it again
: with the hammer and rod. No move.

You will remove the strength of the tube if you heat it much. Welding aluminum is really hard without turning the whole piece into a pool of metal... problem is the extreme conduction of heat away from the site you are trying to heat. Before you get the wood inside to burn, you will have the whole length of the tube at the melting point.

: I don't think any sort of steam treatment will help--the wood would swell and
: the steam would harm more than help.

Yep... same would be true of amonia which would soften the wood but make it swell.

Other ideas mentioned: Drill bit... Unfortunately, the aluminum is softer than the wood. Drill bit will slip off the end of the wood and cut through the side of the tube.

termites... cool idea. Or wood rot or toredo worms... Do you mind waiting 10 years while they do their job? How about giving a mouse a really good reason to get to the other side? Nah! would eat through the pipe since it is softer.

: Or should I get used to the idea of a heavier kayak? Not keen on that. So, I
: figured I'd ask the sharpest bunch around. Any thoughts?

Put it up as an antenna.

Buy new tubing.

Rick