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Thread: <Archive Thread> Building the EX3 - Tips & Hints

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  1. #11
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    Default Re: Building the EX3 - Tips & Hints

    WING

    Tapes & Patches

    Well, here's a picture of all 166 rivets in place through the reinforcement tapes into the center ribs ready to be riveted. What......you didn't want to spend the money on a pneumatic rivet puller????

    P1050739.jpg


    IMPORTANT: REMEMBER TO USE A RAG AND COVER THE EXHAUST PORT ON THAT PNEUMATIC RIVET GUN SO IT DOESN'T SPIT OIL ONTO THE FABRIC.

    P1050740.jpg

    Grommets are installed using PolyTak. I put it on the grommet and stick it onto the fabric. Caution: Get it exactly right over the tracing you did with pencil on the fabric before sticking it because once you touch the fabric, it's pretty much where it's gonna stay!

    Next you want to put down 2 coats of PolyBrush on all the tape areas. The first thing I do is to go down the wing and saturate the reinforcement tape (with the rivets in it) with brush. Don't brush it on.....just use the edge of the very wet brush and run it down the reinforcement tape and let it soak in good. If any is trying to run "outside the line", catch it but otherwise, let alot of the brush soak into the reinforcement tapes.

    Then go back over all the areas being sure to get a good coat of brush at least....to the outsides of the lines and a little over it. It doesn't really matter because it will all have brush on it eventually. With PolyBrush, the trick is not to over brush it. It dries REALLY FAST, just just get it down on the fabric and make a quick pass or 2 after its down to smooth it out some. Try not to leave a thick edge as it will show up later. If you try to keep brushing it after about 5-10 seconds (depending on the temps) after you lay it down, it will be drying and show the brush marks....so slosh it on, even it out and go on. If you get some puddles or splashes outside the lines, just run over it with the brush to smooth it out. If too much or you catch it after its dried, just use a rag with a little MEK to clean it up.

    Put 2 coats under all the places the patches will go as well. The patches go OVER the grommets. On the top of both wings there will only be the 1 teardrop grommet and patch for the pulley cover.

    P1050741.jpg

    Let it dry a couple hours between coats. The way I do it is that I just work on 1 side at a time. I just shrunk this side of the fabric at 350 degrees (the other, bottom side has only been shrunk at 250 so far and has no tape lines, rivets, etc) and I'll go ahead and mark the tape lines, put down 2 base coats of brush; install the tapes with another coat of brush and then come back after that dries and put a final coat on top of all everything. Then I will flip the wing over and do the same on the other side. I have a Bogert rotator but I don't use it on the wings until paint. I think it's easier and faster to just leave the wing on sawhorses until ready to go spray the PolyBrush; PolySpray and finish paint coats.

    Layout your 2" tapes and cut them to length. I start on the top of the wing and cut the 2" tapes by first cutting a round end that will go forward on the leading edge skins and I actually put the end 1/2" below (forward) of the rivets where the 3" tape goes. Just cut the round end and then go the width of the wing and go over the aft false spar and let it hang over about 6" and do a straight, pinking cut on that end. You can trace an outline on the end of the tape from a cardboard cutout if you want but I just fold the tape in half and cut a half moon on it and that works fine.

    P1050743.jpg

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    Later, after we flip the wing over and do the other side, we will do a straight (not pinking) scissor cut on this end where the center of the 3" tape will be that goes over the false spars and aileron coves. For now, we will just install them with PolyBrush back to the aft edge.

    On the aft end of the wing tip box, the tapes that go over it, we will cut with straight scissors directly in the center of the wing tip bow. We will later cut the one from the other side at the same place and that joint will be covered last by the 3" tape that goes around the outside of the wing tip bow.

    P1050744.jpg

    Both the PolyFiber manual and Cubcrafters says ...... ".....when installing the tapes over the rivets and reinforcement tapes on the center ribs, you will not be able to get all the air bubbles out around the rivet heads......". Well, I have found a way where I can install them with the least amount of air bubbles I think. I'll try and make a little video showing me doing it but I'll explain as well in writing so as not to take so much download time for the video. It isn't perfect but I think it works the best.

    UPDATE: GO TO POST #63 ON THIS THREAD TO SEE A SHORT VIDEO OF ME INSTALLING TAPES OVER RIVETS.

    PolyBrush evaporates and gets thick really fast....EVEN IN YOUR CONTAINER. So don't put much fresh polybrush in you container (the one you are using to dip your brush into) at a time and once it starts getting thick, replace it because it will NOT work well on these rivet heads when it thick and setting up quickly. Remember, we are wanting to keep it so wet under the tape that the tape does not stick to the fabric on the sides yet so we can PUSH the air bubbles around the rivet heads out!

    The trick to it is this:

    1. First remember that we want it REALLY WET on top of the rivet heads/reinforcement tapes and the fabric where we are going to lay the dry 2" tape into. I know Cubcrafters says to do it dry......to lay the tape on it and then put the Polybrush over the top. I tried it that way a few times and it just doesn't work as well as having it really wet.

    2. We will start at the forward end on the leading edge skin (the rounded end of the tape). You should have you a pencil mark 1/2" below the rivet head that is inside the markings where the 3" tape will later go. Start by taking your very wet brush (I stick it into the brush, lightly touch it to the inside of the container to keep it from dripping and then applying it) and quickly just run a quick coat down between the lines where the tape will go getting it good and wet, then get your brush REALLY wet again and holding it sideways, just run it lightly along the reinforcement tape and rivet heads (even dab it at each rivet head to leave a puddle of brush). You actually want the brush to be pooling around the rivet heads. Don't brush it......just let it run off the brush onto the reinforcement tape and rivet heads. GO FAST.....it will dry fast....... If it dries at all or even gets "sluggish"....it won't work. Starting at the front just go maybe 7 or 8 rivet heads as you work from the front of the wing. We will do that first and then move to the rear and do the rest of the tape.

    3. Next wet your brush quickly again and leave it on top of your container to have it handy for after the next step.

    4. Take both hands and using your right hand (if right handed) hold the front of the tape while your left hand holds the tape so that it does not touch the wet brush you just laid down. Put the very front, rounded end of the tape right on your mark 1/2" down from the leading edge rivet while your left hand keeps the rest of the tape off the wing. Quickly now take your right hand and get your wet brush again (dip it and just touch the side of the brush on the side of the container to keep it from dripping too bad.)

    5. With the wet brush, go over the front of the tape you just stuck down and then start brushing down the center where the reinforcement tape and rivet heads are.....pushing the tape down into the wet brush as you go. The trick here is that you will work the air out of the edges of the reinforcement tape and around the rivet heads as you go. Since it's really wet, you can easily push the air out from the center and around the rivet heads towards the outside of the tape. Brush back away from you towards your left hand because you will be pushing the air out the backside as you go. Since you are holding the tape up with your left hand and only letting your wet brush push it down into the brush as it moves towards the aft end, the air has a way to escape. If you see air bubbles, just hold what you have and be sure your brush is wet and try and push it out from the center towards the outside edges where it can escape. THIS ONLY WORKS IF YOU HAVE IT REALLY WET UNDERNEATH AND THE POLYBRUSH HAS NOT BEGUN TO DRY. You have to move quickly on this as the brush sets up really fast. If you mess up, simply pull the tape up as far as you have to with your left hand until you have it straight or over the air bubble areas and do it again. As you go of course you will have your left hand holding the tape correctly so it's laying down between the lines you penciled in for the tapes.

    6. Be sure you don't leave too much brush on the outside edges, keep smoothing it out as you go before it sets up. If you leave a thick, irregular edge, you will see it through the paint. You can also go back later with some MEK and clean these areas up but easier to try and not do it to start with. After I have a section laid out and into the brush I make one last brush line over the tape on each side edge and ends to be sure it's smooth and not too thick. If you are too slow, you will be too late and just leave brush marks. If your brush seems to "drag" in the brush, it's too dry.....stop and leave it alone or put more wet on.

    7. Next just go to the aft end of the wing and lift it up just enough to do the same thing to the rest of the tape. When you get to the edge, just do the top part for now and let the extra tape hang off the back edge for now. We will straight cut these ends later and join the other side tapes where the joint will be under the 3" tape that goes in the aileron cove and false spar and you will never see it.

    8. Lastly, put on the 3" leading edge tape that will go over the seams of the 2 wing fabrics as well as the forward ends of all the 2" center rib tapes.

    P1050746.jpg
    NOTE that in this photo it shows the small tapes over the rivets behind the fuel tanks on the flap false spar. Cubcrafters changed this now that you don't install fabric rivets or these tapes over that false spar area. The Polybrush will stick to the full false spar metal now and be sufficient they say. So that 2nd and 3rd small tape strip from the wing root you will not do now.


    P1050747.jpg

    P1050748.jpg

    P1050749.jpg


    Note what order you put your tapes on around the fuel tank bays. The short tape over the aft end #2 tail ribs should go down first, then install the forward and aft edge (inboard to outboard running tapes around the fuel bay) tapes and then the forward to aft tapes that go over the #1 & #3 double ribs. Note that the tape that goes around the #1 rib will be 1 solid piece that goes all the way around the wing and joins with a straight cut just like the others, in the false spar area. Just to the top piece for now and clamp the tape to the wing on the bottom side until later.

    Then put on all the 2" rib tapes and then the 3" leading edge tape. Don't install the wing tip bow tape until you finish the bottom side.

    Also, on the round 5" grommets that are clear...be sure and file down the little teats that are on them from the injection molding process. If you don't file them down smooth, the patch will never go over it nice and even and will stick up and leave a very noticeable "bump" there.

    P1050755.jpg


    HERE IS ANOTHER PIECE OF INFO FROM CHUCK & RYANS BUILD THAT IS GOOD

    Taping wings

    Having never covered a plane before, it has quickly become apparent that once the basics are mastered the technique attendant to the details becomes critical. I can’t say if the following is right or wrong, but it worked for me.

    1. Covering the nav lights. There are two small fabric pieces to cover the top and bottom of the navigation lights. The bottom went on first. A bit of Poly Brush was used to hold down just the inner edge. Once dried the iron was used to shape the remaining section around the nav light, then Poly Brushed.

    The same technique was used to apply the top piece, but after ironing it to shape it was trimmed so the end seam was along the center line.



    2. Aft rib tip. A three inch tape was folded down the center to establish a center line. The aft end was held in place with a clamp. The tape was then pulled tight to cause the tape to tend to fold flat and additional clamps applied to about six inches of the nav light. Next the tape was ironed along the outer edges at about 250^ until it laid flat. Finally the Poly Brush was applied, removing clamps as it was glued. Once it dried sufficiently the clamps were removed and the end by the nav light was trimmed with a rounded end using a pattern and Poly Brushed in place.



    3. Forward tip. The forward tip can’t be clamped because it is too darn thick. So the tape was held at the forward leading end with a dime size dab of Poly Tack. Then after it set up another dime size dab was applied about three inches away, pulling it snug. After several dabs of Poly Brush were applied and dry, an iron was used to shape the tape and Poly Brush applied.





    Last edited by Daveembry; 01-16-2022 at 06:56 AM.
    Dave Embry
    "You only live once.......but if you do it right.........once is enough."..

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