I changed my mind about the rudder drive plate and decided to fix it after the new angle meter from Aliexpress arrived. The angle should be 5.2°.
It was a little hard to get a good measurement with all the components in the way I drilled out all the rivets by hitting them with the #30 until I could break off the tip, then punching out the remainder. My punch needed a little clean up to go in nicely.
The horn was bent to its correct angle by giving it some love taps with the hammer, checking, and whacking it again.
A much better fit!
Below shows the importance of measuring 6 times using 4 different methods and cutting once. I measured x/64ths when I should have measured x/32nds and was quite a bit off.
To keep the control surface square I wanted to put a cleco in the far end, but making sense of the drawings took a little while.
In the first photo the rivet going through the hinge is 3/8″ from the top, but measured perpendicular to the end of the short edge. In the second the hinge is spaced 0.057″ from the top surface. It turned out to be much easier to draw and drill once I took the measurements from the correct datum.
I will redo some of the angles on the control horn; one because my initial drills are now off, and another because it was not correctly aligned.
On the left you can see the new drill would “snowman” with the other, and on the right one of the rivets would be too close to the edge of the clip.
Here’s the layout of the larger angle.
I got these 3/8″ drills from Amazon which came labelled 4.8 mm, but they are actually 3/8″! As the Chinese say, 以实物为准.
I will drill out the corners with this bit then use the step drill to up-size to a 1/4″ hole. I will also need a seamer, and to modify it a bit. I ground a chamfer into one edge of the seamer so it would bend 1/16″ radius corners nicely.
The new angle is much smaller than the old one, but it matches the measurements in the plans. It’s so much smaller that it drops into the old angle.
The front angle required a bit of adjustment as it was also oversize. Finally, the whole assembly fits the control surface much more tightly, and it also more closely matches the other rudder ribs. The last bit of angle was easy to make and trim. The kit came with a ton of angle stock – 16 feet.
I’m glad I committed to redoing this part.