This weekend, I started the practice rudder. Stopped by the local Lowes and picked up a 2' x 3' board so I could make a form to bend the rudder around.
I have a total of four enlargements printed of the tail section, so I figured the easiest way to get as exact of a form as possible was to get out the Exacto knives and trim out a template to trace. An important note here, notice that I am cutting the blueprint along the inner portion of the drawing. Easy logical step to miss if you are not careful, but important because the 1/2 inch tube will be bent around the form in the place of the tube on the blueprint.
Once that was fully cut out, I now had a template I can trace onto the board to cut the form. I used a few tabs of masking tape to hold the template firm to the board and traced out the form with a pencil. Notice the rudder spar is still on the template, meaning we will have extra length of tube once the bend is complete. That will be trimmed up in the final fitting stage.
Looks good! Removed the template (and saved it). The traced rudder form looks clean and smooth.
Got out the trusty jigsaw and cut out the template. Save the cut off scrap edges of the wood, those will be used later to hold the bent tube in place.
Starting to look like a rudder! Even though it is just the form for the tube frame.
Although it looks like a very smooth cut (and it is quite smooth), this being an aircraft build I will go the extra mile to be as precise as possible, so out comes the trusty Harbor Freight sander to buff out the few imperfections in the curved part of the form.
Once sanded smooth and cleaned of debris, the form is laid out on the work tabled and screwed in place with a few deck screws. Two notes here that almost tripped me up. First, make sure there is enough room (at least 2 inches or so) around the form so that you can use the work table as a sort of brace to keep the bend level along the plane of the bend. Second, notice how close my form is to the wall of the shop? Well, that was a bad idea. That 7' tube piece, when first starting the bend, was almost too long to bend as it was almost blocked by the wall. Make sure you have cleared a radius around the form (on a level plane) at least as long as the tube you are bending.
To start the bend, I place the 1/2 inch tube against the form, then used another deck screw to lock it in place with a piece of wood board scrap from the cutting of the form. The tube is longer than needed, so I left a couple inches of extra tube to trim later. THIS IS IMPORTANT: remember that this tube will eventually be riveted into the rudder spar, so leave extra tube on the ends and only trim to size after you fit it with the other tubes. Last thing you want to do is trim the tube too short by an inch and have to do it all over again.
This was kind of exciting: the first bend of tube for the aircraft. I was very careful to bend slowly and with even torque along the way, watching for creasing of the tube. Smooth and even pressure, no creasing observed.
With the bend complete around the form, I screwed in another piece of scrap wood on the bottom end to hold it in place. The big piece of scrap is screwed in as well, but it is not a pressure point for the bend so it is not something I needed to do, but it looks good!
Cleaned up the shop, and left the tube in the form for the night. I'll probably take it out tomorrow and see how well it took to the shape.
Planning time: 1 hour
(Counting this as all planning time because it is the practice rudder, not the one that will go in the aircraft)
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