Page 17-04 Wing Walk Doubler gap and primer questions

Today I test fit the left wing walk doubler. As the instructions warn, there is quite a gap on the bottom edge because of the curve around the leading edge. How did you earlier fellows handle this? I have the Cleaveland tool with the rollers, so could use that, but I'm wondering if it will be enough. Take a look at this picture: http://www.mykitlog.com/users/display_log.php?user=BigJohn&project=639&category=0&log=77092&row=1

Second issue is whether to prime the top of the wing skin and the bottom of the doubler where they come together. I have opted to prime all internal parts with NAPA 7220, so everything inside the wings except the skins themselves are primed. Following that formula, it seems as if I should have a coat of prime between these mating surfaces, but don't know if it's really necessary, or desireable. Wondering what others have done.

I did not have the Cleveland at the time I did mine, but it should have no problem. If need be you can give a slight twist to the Cleveland to make a wider bend. I played around with some scrap I had and discovered it is a great tool. As to the priming, how many opinions do you want? Just search the Van's forums and you will get as many answers as there are members. I am using Stewart water based primer sealer only on scratched, non-alclad, or parts where water may collect. I live in a mild climate so I am not too concerned. If I lived in Arizona I wouldn't prime anythin.

Mark Henderson said:

As to the priming, how many opinions do you want? Just search the Van's forums and you will get as many answers as there are members. I am using Stewart water based primer sealer only on scratched, non-alclad, or parts where water may collect. I live in a mild climate so I am not too concerned. If I lived in Arizona I wouldn't prime anythin.

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Thanks Mark. I will try the Cleaveland tool tomorrow. As to the priming, I surely don't want to open that can of worms again! I have already made my decisions there - NAPA 7220 rattle can - my question is very specific - is there any advantage to a coat of primer between the top skin and the doubler - since it is a possible place where moisture could get in and remain there.

I just used the hand break tool and gave that edge a good break. John, just checking, are you sure you used the correct 120 degree countersink on the spar? Skin holes dimpled? Doubler plate dimpled? It looks like the end is rising up more than the middle. Maybe it is just the picture angle.

Big John... I removed the washers on a hand break edge rolling tool so that the rollers did not touch the rivet holes and partially rolled the edge after much practice on scrap. FWIW, how easy is it to insert, but not pull, the rivets into the spar and into the holes on the inferior leading edge of the wing doubler? I had no trouble on the left wing, but difficulty pre inserting rivets into the spar on the right wing. I had to reverse the sequence on the right wing doubler.

Jeff

BigJohn said:

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Second issue is whether to prime the top of the wing skin and the bottom of the doubler where they come together. I have opted to prime all internal parts with NAPA 7220, so everything inside the wings except the skins themselves are primed. Following that formula, it seems as if I should have a coat of prime between these mating surfaces, but don't know if it's really necessary, or desireable. Wondering what others have done.

Click to expand...

Hi John My 2c,

if there is only one area you should consider priming on the RV12 then it is THIS area. The doubler sits on TOP of the RV12 wing, the wing dihedral will always make any water, moisture and gunk flow inboard underneath the doubler. Then with the plane sitting outside it gets nice and hot again, expanding contracting. The you and your passenger walk on it making it move some more!!! That area is going to take strain and hold water, prime it!

Mask the top of the wing around the doubler then shoot your favourite primer on top of the wing and then again underneath the doubler. 10 years down the line you will be glad you primed underneath the wing doubler area.

Regards
Rudi

Thanks for the help.

Comments re: bending edge on the doubler. My edge breaking tool would not work due to the dimples. Sure would make it easier if the piece came without the dimples and the builder put them in after breaking the edge. Tried a few other suggestions and finally just sandwiched the part between two strips of wood with the edge sticking out, clamped it to my workbench, and bent it by tapping on it with a hardwood block. Came out perfect after a couple of trail runs and I got a great fit. Installed the part to the wing with no problems.

Comments re: priming the doubler. Rudi confirmed my thoughts on the issue and I primed both surfaces.

Wing Walk Doubler gap question

This is about the solution used by John Peck:
"Tried a few other suggestions and finally just sandwiched the part between two strips of wood with the edge sticking out, clamped it to my workbench, and bent it by tapping on it with a hardwood block"
How did you manage not to crush the dimpled holes between the strips of wood sandwich? Did you leave the dimpled holes out of the sandwich?
I am also wondering if there is a problem not breaking the edge, after all it is not clear the gap will be a problem after riveting (of course VANs saying that "it may be necessary to break the edge" is not helping as you will know if it's necessary after you set the rivets!). I am curious to know what you guys did, how many did not break the edge and are happy with the results?

Sorry....

... I can't remember! In my defense it was a year and a half ago.

Thanks John

This thread saved me from making the same mistakes you made in the wing doubler. Your trouble with fluting the wing tip rib helped me as well. It's not as easy as it looks.

Patrick

I've used the Cleaveland Edge Roller with great success. I used it on any location where I wanted a nice lapped joint.

Edge Rolling Tool