I am having to wait on riveting together my vertical stabilizer until the weather improves and I can prime.
So today I cut apart, shaped, deburred and polished a bunch (25) of stiffeners and what not for the rudder. I also am starting to mark these with a small engraver to identify the part #.
Prior to trying the engraver I confirmed that this is OK with Van's. They even do it on their own parts. Takes me no longer than a sharpie and I know I won't get my parts mixed up later.
Onward.............I am OK identifying my parts at this point, but I am sure that as soon as I start throwing primer on things it will get a bit scary.
Also put a new bandsaw blade on my 10" bandsaw made for aluminum. Cuts clean and like butter, much better than my more aggresive wood blade.
I have made good progress the past two days on my rudder. I am building much quicker now that I have the basics down. Below is the frame, went together quickly.
And now one skin on......
Hopefully I keep up the new momentum.
was how to accurately machine countersink the trailing edge wedge. It is a triangular wedge that is used to rivet both trailing edges of the right and left skins. It is sandwiched between the two. As a result, the countersinks have to be perpendicular to the face of the wedge on each side.
So my solution was to put my angle vise on my milling machine, and set it so one side of the wedge would sit level, and drill away. I made a backup piece of tubular steel to raise it up and put a hole in it since the countersink pilot would go through the other side. Worked great, I was able to drill all of the holes on both sides in 20 minutes. Depth was accurately controlled by the z-axis of the mill. It is kind of my drill press on steroids.
Rudder now disassembled and deburred, prepped and ready.
And finally my parts laid out ready for the prime. And finally, my freshly primed parts......
All the dimples I did with my big dimpler. It is awesome. I made a removable shelf between my benches to support it. My skins slide over the carpet, and I can handle large skins by myself.
I made a cheapo laser sight to help locate the pin underneath the skin. $2.95 Off of Ebay. Those Chinese.
I will have to get more screen or mesh upon which to paint. I didn't have enough for the small parts, and the spray blows the small parts up in the air. It was rather a pain in the keester keeping things from blowing off the table or into one another. Also learned to test the gun after adjusting the pressure. What a bozo.
But all good. Will let things set up for a couple of days, then finish with the dimpling and then assembly. Looking forward to seeing a finished rudder!
This shows the sequence of back riveting the stiffeners. Below is dimpled skin with rivets placed in the holes. They are held in place with tape. The stiffener will be placed over the rivet tails.
Like this....
Then the back rivet set pushes the pieces together tightly and allows for easy riveting. On the back side is my large and heavy steel riveting plate.
Perfect shop heads after the tails are set....
And ready to put together.
Below is the trailing edge clecoed up after I applied the Pro-Seal sealant. The sealant glues together the trailing edge to allow easier double flush riveting. It took a LONG time for the Pro-Seal to cure well, I ended up giving it 2 weeks. Glad I did, it stayed straight and looks good. I had an old piece of square aluminum tubing that was straight as an arrow, worked well.
And this was how it looked for 2 weeks.......
Rudder almost complete! The trailing edge is notorious for getting twisted due to the double flush riveting. I was pretty paranoid about it, but in the end it all came out well.
My rudder standing up on the leading end. Not a perfect photo to show it, but the trailing edge has been double flush riveted, and looks pretty decent. It is as straight as can be. All I have to do is roll the leading edge, and add the counterweight.
Rudder is finally complete! Yeehaw!
The final step was to fit the counterweight, bend the skins and bolt/rivet all together. I sandwiched the skin to bend as the plans called for, but added some supports so as I bent the skin with a block and mallet the frame didn't take a beating. Worked great, no damage or booboos.
Below is the counterweight end all buttoned up. It should work well.
And I couldn't resist laying the rudder up against the VS.
The fiberglass tip and fairings will eventually finish off these parts. Now it's time for the horizontal stabilizer!
The bottom fiberglass fairing needs a tail position/strobe light. So I got to buy my first (expensive) electrical component. Of course I had to hook it up to 12v, and it is blinding! Although it was very fun, I digress.....
The light uses two screws for mounting, top and bottom. Not wanting to lose my newly acquired expensive tail light at 10,000 feet, I decided to make two screw sleeves for it to mount into. I took some 1/4" brass rod and chucked it up into the lathe. Scored it around the perimeter for retention, and then drilled about an inch hole down the center.
Then I put a 4/40 tap in the drill chuck and ran it in a few times until I had about an inch of threads inside. (slow speed, in and out, plenty of lube). Made up two of 'em.
I then put them against the disc sander, and put flats on all four sides. This would give them good resistance to rotation, while the lathe cuts would resist pull-out. Left everything fairly rough to get a good grip with the epoxy to come.
I screwed the brass sleeves to the light, with a couple small o-rings so I would make sure not to screw up the light base. I taped the base up well and lubed it a tiny bit.
Stuffed some flox/epoxy in the areas in question, after drilling out for the sleeves. I had a little chipping of the gel coat, no big deal. After it all set up, I pulled it apart easily and think I got the result I wanted.
So here it is finally mounted. I can use a couple of 1" SS allen head screws. It is extremely secure and I won't worry when I'm going 200 mph someday.
Decided this was a good time to rivet on the top fairing of the rudder. Clecoed it up, drilled out to a #30, then wet riveted it with epoxy.
Way easier than some of the other fairings.
And finally attaching the lower rudder fairing. Since this will have electrical inside, I decided to make it removable with screws and nutplates. Some have reported damage to this fairing, and recommended this for easy replacement also. At any rate, it was not too much work to make it removable.
Here is the bottom fairing, with holes that were meant for blind rivets (like the top fairing above).
All clecoed up, so the holes are in the right spots. Also note the fiberglass repair on the bottom. When installing the tail light, I must have popped the gel-coat seam on the outside, as it was cracked and opened up easily. So I took down the gel-coat, laid in fiberglass, and finished with peel ply. A coat of micro over this and it should not crack again.
So I bought this cool little nutplate jig. (not a racial slur). Two pins on the side you can see, one larger for the middle hole, and one smaller for the rivet hole. The other side has only the larger pin. For starters, place as shown, the larger pin in the screw hole. Then drill a #40 hole through the small hole on the left.
This shows what you see when the jig is removed, a new smaller rivet hole spaced appropriately from the screw hole.
Then flip the jig over, putting the large pin in the screw hole, and the small pin in the hole just drilled. Drill again a #40 through the hole on the right.
I am not using the hole on the far left. This would be used for a single leg nutplate with both rivets on one end. Not our application here, but handy to have for the future.
When the jig is removed, there are now two perfectly spaced #40 holes on each side of the screw hole. It is very quick, and makes drilling for nutplates very easy. I'm a big fan.
Afterwards, all holes are countersunk for the skin dimple, and the nutplate rivets. Nutplate rivets used were NAD 1097's which have a very small head, making them usefull here. Otherwise I would have to countersink the fiberglass a lot more.
I noticed a tendency for the gel coat to crack easily if stressed too much. So I tried to countersink a little extra to relieve the strain on the fiberglass hole. It worked better. The rivets for the most part just provide resistance to rotation of the nutplate.
And the appearance on the inside..........
View of three in a row.......
And finally with the bottom fairing screwed into place with #6 SS screws. Nice! Peel ply is off the bottom, and ready for micro and a final sand.
*******************************************************************************
No comments:
Post a Comment