Refinishing a wing - any tips?

[Stinky]

I am looking for tips on refinishing a wing. Are there easy ways for one person to work on the top surface and then flip the wing over to work on the bottom? What about the ground getting in the way of the winglet when I have the bottom side up? Should I just dig a hole in the ground for clearance. Maybe build a platform to put the sawhorses on? I have adjustable sawhorses but they only go up to about 39 inches and it looks like I need at least 47". Also, sanding the long wing surfaces in horizontal position is relatively easy, what is the best way to refinish the contour of the winglets?

[TMann]

I was watching an episode of 'How it's Made' a couple weeks ago. I occasionally help my neighbor work on his spam can. We had his wing either laying on the top side or the bottom.

 

In the program, they worked on the wing with the leeding edge facing up. You should be able to do the same. This is the configuration that is used when you do the shear web on the wing.

[mfryer]

I was watching an episode of 'How it's Made' a couple weeks ago. I occasionally help my neighbor work on his spam can. We had his wing either laying on the top side or the bottom.

 

In the program, they worked on the wing with the leeding edge facing up. You should be able to do the same. This is the configuration that is used when you do the shear web on the wing.

I agree, however the trailing edge is more delicate. I would suggest perhaps leading edge down. However that would probably make working on the leading edge difficult.

[Lynn Erickson]

I am looking for tips on refinishing a wing. Are there easy ways for one person to work on the top surface and then flip the wing over to work on the bottom? What about the ground getting in the way of the winglet when I have the bottom side up? Should I just dig a hole in the ground for clearance. Maybe build a platform to put the sawhorses on? I have adjustable sawhorses but they only go up to about 39 inches and it looks like I need at least 47". Also, sanding the long wing surfaces in horizontal position is relatively easy, what is the best way to refinish the contour of the winglets?

I used two sawhorses that are tall enough so the winglet won't hit the ground for the bottom. the top I did on the plane but the sawhorses will work also. it is easy to turn over by yourself . only 75 lbs. pick up the winglet end and roll it over so the spar is sitting on the sawhorse. you are only lifting about 35 lbs. on that end. the winglets are a bit harder to sand while attached but by the time you have done the wing surfaces you will be an expert and find it easy. read up on some of the filling and finishing techniques used on ez's. and sand on the 45 degree angle with coarse paper when cutting filler material.

[Stinky]

Maybe this would be better in another thread but it is related to the frfinish on the wing.

 

It seems my "big fill" coat of micro did not go on very well. There are several places where there was trapped air and as I sanded through they showed up. Some of them are large, on the order of .04 deep. Is that too deep for the Bird finishing technique? Should I hit these with more micro and maybe underfill? If I bring it to almost surface level then the epoxy wipes would take care of the rest. I looked through the posts but my search expressions are not comming up with good matches so I apologize if this has been discussed before.

 

Carl

 

P.S. Okay, time for my best Homer Simpson imitation, "Doh!" I just came across Wayne Hicks' poste where he states, "Almost all the pinholes and large scratches got filled. And I'm talking about very big pinholes, like the size of small peas."

 

So, I guess I'll be epoxying the next time the temps get over 60 for a couple of days here in N. TX. (Maybe I need to look for posts on heating garages...)

[Kent Ashton]

I have found that it takes three applications of filler. First one is heavy and dry. I use West System, squegee on straight epoxy and put the filler on heavy. Smooth it while still pliable with a drywall trowel heated with a propane torch which will get it fairly smooth. Let cure. Sand only until you see cloth. ****It looks to me that you are sanding way too much into the cloth.****

 

Periodically rub the surface with a stiff aluminum square rod maybe 18-20" long. The rod will leave Aluminum oxide smudges on the high points. Sand them down lightly but not into cloth. Circle your low areas with a wide sharpie.

 

Apply a second layer of West, not so dry this time. Again smooth with the hot drywall trowel. Cure, sand, rub with the AL rod, mark low points.

 

Finally, I usually need a third final spot application of filler for a few remaining low points. After sanding and testing with the AL rod, you are then ready for the Bird/Hicks pinhole filling.

[Kent Ashton]

One more thing: When you sand into the cloth, or through the filler to the cloth, the cloth layer is harder than the filler layer usually and it will be difficult to get a smooth wave-free surface because you are now sanding a surface with different hardnesses. You'll tend to ride over the hard points and gouge the soft filler.

 

It will work better to leave more filler on the surface and refill the entire surface if you're seeing a lot of cloth. That gives you a surface of a consistent hardness to work with and it will be easier to level. When finished (prior to filling pinholes) your wing will be one color and you might just see a little cloth faintly below the filler.

[Stinky]

...****It looks to me that you are sanding way too much into the cloth.****...

What you are seeing is actually the remnants of the last paint job. Yes, it does appear to be that wavy but it had flown when I bought it and I have put another couple hundred hours on it before this undertaking.

 

The only two places I am starting to see cloth are up on the leading edge curve. You can make out a line just about directly above the right side of the first aileron attach cut out. On that line, near the left I am just starting to see cloth. Oh, there is a bit showing at the trailing edge too, whoops. The rest is old layers of primer and paint. Seems it had been painted twice before I bought it!

 

One note of interest, just before the big fill I did wipe with epoxy and let it tack up. I added a black dye to the epoxy based on some articles by West Systems. The dye powder was water based and it did make it easier to see when I was sanding in close to the primer. Unfortunately, when I washed the wing off some of the dye activated! That left the streaks and the black cross hatching that you can see. I hope I have not totally hosed myself and that the final epoxy build up will encapsulate that.

 

Carl

[Kent Ashton]

Personally, I wouldn't expect the Bird/Hicks filling to fill large scratches and large pits. I'd Spot fill or do another complete fill layer and sand to get a clean 320-grit surface, leaving only pinholes and 320 scratches to fill.

 

But your post brings up the question of what sort of paint/primer is underneath. The early EZs were primed with a waxy black UV primer that did not stick very well and was prone to flake off the filled surface along with the topcoat in thumb-sized spots. I ended up completely scraping, filling and repainting a Cozy III that had that stuff. The better course might have been to bead-blast all the old paint off and go from there but your in a better postion to judge.

 

I think the Bird/Hicks filling and an epoxy primer will seal in the streaks you're talking about. Good luck

[schmeddz]

I find that glazing putty or spot putty works great for pinholes even up to the size of those pea sized holes.

 

Now before I get griped at, I use the mixable putty that uses a hardner. (MEKP) It gives you about 5 minutes to fill pinholes and scratches and even deep weave. Get it at any auto parts store that sells bondo. Spreads like cake frosting and sands like butter with fine grit sandpaper.

 

NEVER use the solvent based putty! NOT EVER!! It will lift the paint!

[Wayne Hicks]

From your pictures:

 

(1) It looks like your micro may have been too dry or too cold when you attempted to spread it. The telltale sign is in the second picture. I can see where the spreader skipped over a section and cause small peaks in the micro. Dry micro is spread more easily by using a heat gun (or hair dryer) and heating the micro and the back side of the trowel as you spread the micro. Spend more time heating the back side of the trowel.

 

(2) You may have spread the micro too fast. If you're getting air bubbles underneath the micro, this is a good sign the micro is not adhering to the surface as you're pulling. It could be because again, the micro is too dry. Some folks get results with dry micro by wiping the surface first with pure expoy, then applying the micro. Again, heating the trowel helps alot.

 

(3) While the skimcoating technique can be made to fill the large holes and low patches shown in your pictures, it would take too many applications to complete the fill. You'd have to use cabosil to thicken the skimcoats. Cabosil cures very hard and would be hard to sand flush with the rest of the micro. You'd end up with depression in the softer micro before getting the skimcoat fills leveled out. The mucho easier method is to use the microlight. After cure, sand flush and then start the skimcoating.

 

BTW, skimcoating WILL FILL 36 grit sanding scratches and holes the size of small peas. I know you've seen the pictures on my website, but I wanted to provide the link again so others can view them too.

[Stinky]

From your pictures:

 

(1) It looks like your micro may have been too dry or too cold ...

 

(2) You may have spread the micro too fast. ...

 

(3) While the skimcoating technique can be made to fill the large holes and low patches shown in your pictures, it would ...easier method is to use the microlight. After cure, sand flush and then start the skimcoating.

 

....

Thanks y'all.

 

Wayne, you pretty much nailed it all. If I recall correctly the temps were hovering around 68F. I was mixing batches of West 205 with about 33% glass bubbles by weight. (Notes are at home but I think about 400g resin, 80g 205, 160g glass.) Pretty dry. I was also going kind of fast, without extra heat. The last time I tried to use heat it was about as hot as a stolen tamale around here and it didn't turn out to pretty. Maybe I should practice that some. I'll look for some mircolight and have a go at the big holes.

 

Carl

[Wayne Hicks]

I'm sure you mean you were using WEST 105 resin. What hardener are you using? I used the 206 slow the most, but I really liked the 209 extra slow when I was spreading micro over large surface areas (like wings).

 

I tried the 205 fast only once. It exothermed into a big ball within 10 minutes. Was too hot to hold. It never made it onto the plane.

[steve]

the auto body filler you are using (feather fill, mico-lite, est) two part mix is good stuff but learn how it works.

 

get some scrap glass(fuzz cutout,any hardened glass) and drill in a small pee like hole then sand over the hole with 36# then farther out sand with 80#

then with 180# and finally the edge with 320# now fill over it with your putty. now sand it down to 150# just the same as you would if you wanted to prime it, don't waist your time priming it just yet, but rather insert it it to the oven at the lowest setting for 4-8 hours (same as parking the plane out it the sun.

remove from oven and look at what you see, a hole with scratches all around it. re-sand and prime, it will now work just fine in the sun.

putty works a lot like are epoxy as it needs to post cure.

[Stinky]

I'm sure you mean you were using WEST 105 resin. What hardener are you using? I used the 206 slow the most, but I really liked the 209 extra slow when I was spreading micro over large surface areas (like wings).

 

I tried the 205 fast only once. It exothermed into a big ball within 10 minutes. Was too hot to hold. It never made it onto the plane.

Yep, 105 Resin. The hardener could be 206 but I think it was 205. (I'll check when I get home.) The temperature for the day is a mistype, t was actually closer to 60 when I did the fill (Nov 22). I mixed it up in a cleaned out Oxy-Clean bucket. I plopped the the whole mess on and spread out pretty fast but it was starting to kick off by the time I got up to the leading edges. I think I made up four batches in all.

 

 

Carl

[TMann]

Throw some poly over it and follow that with an electric blanket to help maintain a good cure temperature.

 

Start early in the day so you can get the blanket back on the bed before the wife catches on.