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Trailing Edge, 3M tape or Pro-Seal?

mstrauss

Well Known Member
Patron
Working on the TE of the rudder, and I see that Vans is recommending the use of 3M VHB Tape F9460PC. However, I have also see reports that it has not worked well for some people. At the same time, I have read some recommend using Pro-Seal. So what would you recommend?
 
I used tape, but probably more important for me was the use of spare angle I match drilled to cleco on top and bottom of the trailing edge. After doing the tape and letting set for a week with the angles cleco’d on, I then also enlarged the drilled holes in the angle to fit my squeezer and flat sets, and used that to partially set per section 5 from the center to top and bottom at intervals around 10 and continued to half until done. Ended up perfect. I did use the Cleveland tools trailing edge squeezer tool to set with my pneumatic squeezer after all were partially set.
 
Proseal

I used tape, but probably more important for me was the use of spare angle I match drilled to cleco on top and bottom of the trailing edge. After doing the tape and letting set for a week with the angles cleco’d on, I then also enlarged the drilled holes in the angle to fit my squeezer and flat sets, and used that to partially set per section 5 from the center to top and bottom at intervals around 10 and continued to half until done. Ended up perfect. I did use the Cleveland tools trailing edge squeezer tool to set with my pneumatic squeezer after all were partially set.

I used proseal with a 2x2x6 angle. Allowed the proseal to fully cure then riveted in random order.
 
I used tape, but probably more important for me was the use of spare angle I match drilled to cleco on top and bottom of the trailing edge. After doing the tape and letting set for a week with the angles cleco’d on, I then also enlarged the drilled holes in the angle to fit my squeezer and flat sets, and used that to partially set per section 5 from the center to top and bottom at intervals around 10 and continued to half until done. Ended up perfect. I did use the Cleveland tools trailing edge squeezer tool to set with my pneumatic squeezer after all were partially set.

I like the idea of using the angle to get a nice straight edge. Unfortunately, I already final sized and dimpled the skins. I suppose I could just used the wedge to guide the holes for drilling in the angle. I have not countersunk the wedge yet.

When using the angle, how do you rivet with it clecoed on to the rudder? Sounds like you to drill large holes for the squeezer to gain access to the unclecoed rivet holes? That is a lot of holes.
 
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I have not been impressed with the 3M VHB tape. It doesn't really stick to anything well. I scuffed and cleaned the mating surfaces, clamped, and even added heat in other applications, with little success.
Does anyone have any suggestions or best practices for 3M VHB tape?

I would recommend proseal in this case.

JT
 
I've done it both ways... I would say I prefer the tape as it's less of a mess and you don't have to worry about globbing it on too thick. But just about anything will work, it's only there to hold the parts in alignment until you rivet.

As others have said, the angle is very helpful in keeping it straight while the glue/tape/whatever sets up. If you have already drilled and dimpled your rudder you might still be able to fabricate an angle, since the holes only have to be precise enough for a cleco. Remember to drill the holes at an angle just like you did with the trailing edge. I would mark the holes (1" spacing) and drill the angle separately, rather than trying a risky match-drilling operation through the rudder trailing edge.

I have read about builders squeezing the trailing edge rivets with the angle in place, by progressively drilling holes with a unibit. In my case I removed the angle and transferred the rudder to a long piece of steel angle that I had faced so I could use it as a giant backrivet plate.

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Another option

Structural adhesive like Aeropoxy has been used on dozens of trailing edges with great success. Use of the 2x2 angle clecoed to the TE during curing helps assure a very straight TE for the double flush rivets.
 
Angle

I like the idea of using the angle to get a nice straight edge. Unfortunately, I already final sized and dimpled the skins. I suppose I could just used the wedge to guide the holes for drilling in the angle. I have not countersunk the wedge yet.

When using the angle, how do you rivet with it clecoed on to the rudder? Sounds like you to drill large holes for the squeezer to gain access to the unclecoed rivet holes? That is a lot of holes.

The angle is only clekoed in place till the material cures. Its just a straight edge. In fact, the holes in the angle need not be perfect. They could be drilled slightly oversize. As long as the angle is left clekoed till the proseal fully cures.
Apply a strip of wax paper in between to prevent bonding. Excess proseal in dimples is easily removed with a deburring tool.
 
Steel Angle

I used 2x2x1/8" thick steel angle. It becomes a bucking bar with that mass. Drilled every other hole. Cleco every other hole to the angle while the ProSeal cures. Then, tape rivets into every other hole, cleco the open holes to the bar. Back rivet. Flip rudder and back rivet again. Kept it straight.
 
I just did this a couple months ago. I used the tape, but I would use proseal if I could do it over again. A couple lessons learned.

Don't forget to break the edge of the skins with an edge forming tool. The instructions won't tell you that (at least for the 7 model), but it will cause gaps in the trailing edge if you don't.

Make sure to clean the surfaces well and I'd recommend not having any primer where you put the tape...unless you're confident that your primer is really tough and won't pull away from the surface. If the primer pulls up, it will ruin the adhesiveness on the tape.

I used the wedge to mark out holes in some aluminum angle that I purchased at Home Depot Aviation. Then drill the holes and cleco the angle to the trailing edge to keep things straight.

My rudder trailing edge didn't turn out well due to the two lessons I learned above. With that being said, I'm going to be ordering an RV8 rudder at some point anyway, so I don't intend to use it. I used it as more of a practice piece.

Hope that helps.
 
I tried everything, but in the end, it was neither proseal or tape for me.

Using a big piece of angle will work, but I found that just drilling and clecoing directly to a flat worktop works just as well (and is a lot easier to drill through). I tried a version of pretty much every method mentioned on the forums, and at least for me, drilling/clecoing directly to the work surface ended up being the easiest way to keep the skins aligned and flat for drilling. I then pulled the trailing edge wedge out and used a 3D printed wedge holder and my drill press to countersink the holes. With everything prepared, I clecoed it all back together, but not to any work surface this time. With it clecoed, I just slid the whole trailing edge off of the bench and used a squeezer to partially set all of the rivets. Because the whole thing is clecoed while you're setting rivets this way, you don't really have to rely on any adhesive (I started using 3M tape, but by my last control surface I didn't use anything). Once the rivets were partially set, I flipped the whole thing over and used my large back rivet plate and a mushroom set to finish fully setting each rivet. I know some people fully squeeze the rivets using angled sets, but I prefer how a mushroom set can really finish tightening up the edge.

Had I known for my 9A that I needed to build a perfectly flat sacrificial worktop for my flap/aileron construction anyway, I would have built it early and used this method for all of my tail surfaces as well (the rudder might be the only exception since I think it would be hard to lay flat, but you could still figure out how to get it done). With clecos in place the whole time, you don't have to worry about proseal or tape at all. My flaps were my last control surface and where I finally figured out the method that worked for me. The trailing edges have zero wave, and this method was by far the least stressful and easiest for me.

Whatever you try, don't stress too much over it. The first few times are going to be a learning curve no matter what. My trailing edges got exponentially better with each one.

(sorry for the goofy photos - no matter what I try they rotate on me)
 

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I used the tape and it worked great. As said before either tape or what ever is used is only there (sort of sacrificial) to hold everything together until riveted. Don’t over think it, my opinion is the tape is much lighter than using proseal and the like which won’t create a lot of weight at the edge possibly helping with the wild flutter conversation.

Definitely use a long, straight piece of cheap angle from the hardware place and leave it clecoed in place until the tape cures up and then follow the plans (section 5). Oh and for sure roll/bend/treat the trailing edges so there isn’t a gap. I failed to do that and it’s noticeable. I also used the Cleveland trailing edge rivet set and loved it. Good luck
 
I like the idea of using the angle to get a nice straight edge. Unfortunately, I already final sized and dimpled the skins. I suppose I could just used the wedge to guide the holes for drilling in the angle. I have not countersunk the wedge yet.

When using the angle, how do you rivet with it clecoed on to the rudder? Sounds like you to drill large holes for the squeezer to gain access to the unclecoed rivet holes? That is a lot of holes.

I only enlarged every 5 or so holes on the angle, and I uncleco’d and moved the angle. Tedious but it worked. I do have a pneumatic cleco gun, so that helped a lot. And yes I think you could just use the wedge as a guide, but don’t drill through your wedge, just mark, don’t want to mess up the cord line holes.
 

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Keep it simple, I used some angle as a backer and slightly thickened epoxy (Aeropoxy as I had some to hand), the riveted while the epoxy was slightly soft.
 
Did it both ways - prefer the tape

I used proseal on the rudder and elevators on my -10. I switched it up to tape for the ailerons and flaps and I wouldn't go back. For me it was easier, cleaner and had better results.

I was going to cleco to a straight angle as others have done but was concerned about the straightness of an aluminum angle. I ended up just cleco'ing straight to my "workbench". In the case of these items where I want a really flat surface, I used an interior door blank that was perfectly flat (at least flatter than my normal bench). I just drilled right through the door and set clecos as I was making the initial match drilling of the wedge.

Then I cleaned the TE well, taped it and let it sit for a few days to cure. Then backriveted it, starting every 10 rivets, then 5, then 2, then done. I was very happy with the results.

I find that no matter how straight you get it with the tape or proseal, there is going to be some distortion as you rivet. Kuddos to the folks that have figured out how to rivet while leaving the angle in place. If you careful with your riveting, I think you can get good results without it. I just kept an eye on it as I went to make sure I didn't have any waviness. You can make small adjustments while riveting, even after riveting.


Note the flaps on the -10 are longer than my door blank. I let the ends overhang about 8" and still got good results.
 

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I've used both tape and sealant. I prefer the quality of the sealant but keeping it out of the countersinks while it cures can be difficult. On my flaps I used a one-inch wide Semco roller attachment to the sealant gun. Rolling sealant onto the trailing edge this way helps keep the countersinks sealant free unless you roll it on really thick. It's gotten a bit pricy in the last couple of year though.

If you want to keep it inexpensive, get a foam roller from HD or Lowe's that's about 2 in wide. Do not use a fuzzy roller as it'll leave fuzz in the sealant. Cleaner, quicker and more accurate than using a popsicle stick.

https://skygeek.com/semco-232693-1-roller-nozzle-assembly.html
 
Proseal for me. But I guess this whole tape idea came along long after I did my last riveted trailing edge. The real magic happens in the setting of the rivets super slowly with thought and intention. Through some artful craftsmanship you can drive what looks like a horror show to start, into a perfectly straight trailing edge.
 
how about for the foam ribs?

good discussion regarding the use of 3M tape for trailing edges.

I was planning to use the tape for the elevator trailing edges of my -10, but does anyone have insight to the usefulness of using the tape to adhere the foam ribs?
 
No 3M tape on foam ribs!

Please do not use the 3M tape on the foam ribs. The foam ribs are a different application than the trailing edges.

The tape or tank sealant is used on the trailing edge to hold everything firmly in place while you rivet. The rivet line secures the structure. If the tape or the sealant lets go after, no big deal other than a little cosmetics.

The foam ribs are structural items. They must be permanently adhered. The sealant penetrates slightly into the foam, generating a permanent bond. The tape would not give a sufficient or permanent bond.

At least that's my understanding of the situation...
 
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I agree with Eric and I would not use the tape on the foam ribs.

For trailing edges on my 10 I have used both methods and while the tape is less messy I found that the pro seal did a better job of actually sticking everything together. But both seem to work well enough to hold everything until you get the rivets in.
 
Agreed, No tape on foam

Please do not use the 3M tape on the foam ribs. The foam ribs are a different application than the trailing edges.

The tape or tank sealant is used on the trailing edge to hold everything firmly in place while you rivet. The rivet line secures the structure. If the tape or the sealant lets go after, no big deal other than a little cosmetics.

The foam ribs are structural items. They must be permanently adhered. The sealant penetrates slightly into the foam, generating a permanent bond. The tape would not give a sufficient or permanent bond.

At least that's my understanding of the situation...


That was my major concern too. Lack of effective adhesion to the foam.

Since there is no fuel concerns in this application, what would be a reasonable alternative product?
(Kinda wishing i still access to a chem engineer co-worker from a prior job)
 
I think this has already been pretty well covered, but I also used both (tape on the rudder builders choice, sealant on the elevators per plans). Having done both I think the sealant works better, and it wasn't too difficult to use.

I highly recommend these two products:
Cleaveland Tool Countersink Jig for Trailing Edge - makes countersinking a breeze with the drill press
Trailing Edge Squeezer Sets - I riveted my trailing edges with a squeezer using these sets and it was a breeze.
 
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