Bending the Trim Tab   February 13th, 2007

A lot of people seem to have trouble with bending tabs on the trim tab, just as with the elevator tabs. This didn’t turn out to be so bad, after doing a mediocre enough job on my elevator to warrant cutting them off and replacing them with a rib.

The main thing I learned when doing the elevator was to use something with sharper edges than a piece of 2×4. I decided to try to make the bending blocks with 3/4″ MDF, and was very pleased with the results.

The first picture shows the trim tab clamped in the bending blocks, and ready to have the bottom flap bent (the trim tab is upside down). I used a small piece of 2×4 to gradually bend the flap down. I started from the left side in the picture and made my way to the right, where the flap is really short. I got to the point where I couldn’t bend it any further, and it looked like the second picture below.

I realized the angle on the bending block was a bit too small, and the bottom flap was grinding against the unbent top flap. Rather than fabricate another set of blocks, I just sanded down the edge to clear the unbent flap, and then used my rivet gun with very low pressure to get a sharper bend. I used some painters tape on the rivet set to keep it from scratching the aluminum.
I repeated the process with the other flap, first bending with piece of 2×4 and then with the rivet gun.
And here is the result. Nice and sharp angles, no cracks in the aluminum, and both of the flaps didn’t get too beat up in the process.

This picture shows the other side of the trim tab. Basically the same process, but the two flaps are smaller.

These two pictures show how I used a piece of wood (in this case not a 2×4, but a smaller strip I had laying around) to do the initial bends, before using the rivet gun.
And here is the rivet gun again, being used to clean up the bends. The picture on the left shows the finished bends.
Finally, just to get a feel for where this piece fits on the plane, here is the left elevator with the trim tab sitting close to where it will be eventually attached.

This entry was posted on Tuesday, February 13th, 2007 at 1:34 am and is filed under Empennage, Trim Tab. You can follow any responses to this entry through the RSS 2.0 feed.Both comments and pings are currently closed.

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