Fri May 7 2010

Fabricating rudder stops

You may recall from the last entry that I didn't have any more material to make the rudder stops from. Well, today I decided to make them out of some 1/8 x 1 1/2 x 2 6061-T651 square corner angle I had laying around. This material is somewhat softer than 6061-T6, but I figured it should be fine for the stops. Here's the left stop after a couple hours of work. These are really fussy to get just right so the rudder has the correct travel, but not too much, the stopping surface is nice and flat relative to the rudder horn, and the the aesthetics are good.

Although in a perfect world, the skin should be flat where these rivet on, there was about 1/64 inch of curvature at this location, so I had to file the back side of the stop to create a very slightly concave shape allowing the stop to seat against the side skin without any (significant) gaps.

When it came time to locate the first rivet hole, I used two tiny (3/32 diameter) NIB magnets my brother, Chris, had given me. One fit into the pre-drilled rivet hole in the skin (behind the rudder stop) and the other one showed me where that hole should be on the front of the stop. I did a careful job of marking this location, removed the stop, and drilled.

Here's the left stop clecoed to the fuselage with the first hole. Looks good! The other three holes were laid out and drilled on the bracket, then drilled through into the skin and bulkhead flanges.

The other bracket took pretty much an equal amount of time. Hard to believe you're looking at about six hours here. They came out pretty well, although the stop for the right side is really about 1/16 inch shorter at the front edge than the left stop. Two other things worth mentioning. I'm using 3/32 rivets to hold these on rather than 1/8 rivets. I figure they'll be fine and should be plenty strong. Also, the top two holes on each stop had to be countersunk freehand (without the countersink cage) since the flange was in the way.