Carlson Skunk Works

Well, I have continued to make progress on Sawdust. Tuesday evening I took the elevator out to the garage and proceeded to shape the trailing edge and sand things. Now I need to order more plywood and glue and I should be able to really complete the elevator. In the mean time I need to focus on making and installing the trim tab, the hinges and the metal parts like the elevator and trim tab horns.

Yesterday I took a bit of a diversion and worked on the link between the stick and the elevator bell-crank. Chris calls for a couple of “bearings” to be installed at each end of this link. The bearings have a threaded end, i.e. they are a swivel on the end of a bolt, sort of. There is a length of 4130 steel tube between the ends. The bolt ends of the bearings are 1/4 x 28 threaded rod. Therefore, the steel tube needs to have a threaded hole that will accept these bearing ends.

What the plans call for is an tube with plugs at each end. The plugs have been drilled and threaded and are secured to the tube by rivets. Well, I sort of followed this idea, but I used four inch long chunks of steel rod for the plugs and drilled and threaded my own holes. The plugs will be welded into the tube, but will have to wait with this until I get the stick end and the bell-crank finished to accept the bearings.

Here you can see the tube and the two plugs. The plug on the right shows the threaded hole and the one on the left has one of the bearings installed.

The plugs are four inch lengths of 5/8″ steel rod. This rod just fits inside of the tube, so it should be fairly easy to weld things up.

I will leave about an inch of plug sticking out of the end of the tube. The bearing has about an inch of threads on it, so the threads will remain outside of the tube. I will probably cut fish-mouths into the end of the tube and drill holes to accommodate securely welding things together. This is probably overkill, but I don’t want it to fall apart on me in the air.