Rust removal

[MikeB]

The Champs I've previously covered had very little rust on the fuselage and control tubing and I could basically sand the surfaces down and prime with epoxy. Not so with the 11CC Chief I just bought. I tested the tubing with my spring loaded punch, no 'poke through' but there are some rusty surfaces I need to deal with. It's probably been covered before but what's the recommended product and air pressure to use a 'sand blaster' (hate that term) to clean up and not damage the tubing further. Apparently the Chief spent time on floats in Nothern Minnesota which might account for the rust.
Thanks, Mike

[Richard Murray]

Mike,
I bought a conversion kit and turned my sand blaster into a soda blaster. You can take paint off of aluminum without damage.
Richard

[clipperfixer]

Mike,
this goofy thing is what I used:
http://www.amazon.com/Campbell-Hausfeld ... nd+blaster

I would recommend that you don't use sand. Breathing the silica is not good for you. I highly recommend a product by Black Diamond that is sold at Tractor Supply here. I believe it is coal slag. Anyway the media comes in various grits. The higher the number of the grit, the finer the media. I used the Black Diamond 40/80 grit in that cheap blaster and it worked great. I don't know how much you are blasting, but I built a booth and blasted my whole Champ airframe with that set up. I have used various blasters and media over the years and I don't think you can beat that setup for price, and results. The media can be used over numerous times (you will have to sift it though) and if I recall a 50lb bag (or thereabouts) was $7.99. I think I used about 8 of them to blast my champ. You will need a decent size compressor and I ran about 85 psi with the fine media.
Ray

[MikeB]

Compressors not a problem as I have a 60 gallon five horse unit. I don't like breathing anything 'bad' having spent the first years of my working career as a diesel mechanic and breathed clutch and brake dust (bad stuff). I do have a Hobby Air fresh air supply that I use for painting so I suspect that would help some but I didn't intend to use sand any way. Basically need to know the options and the plus and minus.
Thanks,
Mike

[Jerry Jackson]

Mike

I used a home-built booth, a 50-pound pot, and 80 grit aluminum oxide. The aluminum oxide cut good and was reused by vacuuming it up and sifting it through a screen bought from Northern Tool. I used about 100 pounds and have maybe 40 pounds left. I used a home-built turbine forced air compressor and a Tyvec suit and helmet. IMO, it would be crazy to do the work without a suit and forced air.

I hated doing the blasting! It was hot, dirty, the abrasive leaked out of my booth and made a mess. It was a PITA to pick up the used grit, sift it, and reload the pot. I had to be careful to follow a particular sequence to prevent clogging of the hose/gun. Airborne dust, dust on my visor, dust on the tubing and poor lighting all combined to make it really hard to see the work in progress.

But I did get the job done. I cleaned the tubing and applied Stewart's System primer. It is amazing how hard it is to apply an even coating to that assembly of tubes! I recommend applying two light coats using different color primer to ensure complete coverage.

Now here is the important part! You MUST apply a top-coat of paint to the primer to prevent rusting! I didn't. I mistakenly assumed that once primed the metal would be protected and I could delay painting it until I had finished all other work. Not true! Belatedly, Stewart's System now advises that primer alone is porous and rust can form beneath it. A top-coat of paint is needed to prevent rusting. After several years I found that my fuselage is rusted and I am going to have to do the entire job again!

I hated the procedure I used so much that I am planning on changing it next time. I plan to do the work outside using a cheap abrasive that I don't have to re-cycle. I will still use a forced-air suit. I will enjoy the greatly improved visibility and escaping the need to clean my hanger of leaked abrasive. Being on rough ground will interfere with using the pot and I may well try the Campbell-Hausfeld backpack rig described by Ray.

Jerry Jackson
7ECA 65-TC
8T8

[MikeB]

Jerry,
Thanks for the insight. I intend to clean the airframe outside (it doesn't always snow in Wisconsin ). Kind of interesting regarding the original primer you described. Superflite 2 only recommended priming the airframe with epoxy primer. The later, Superflite 6 said to prime with epoxy and shoot a urathane (two part) color coat over it. I guess it makes sense anyway as you'd want to paint the air frame and control tubings but the original directions never said that.

There is a company that does professional 'blast cleaning' locally. One of my friends had the metal parts on a 37 Lincoln he's restoring 'derusted' by them and guess it worked out well but I'd be concerned they would be too aggressive on the thin tubing.

The Stewart system primer may of a different composition than the organic mineral based, too. I'm thinking I'll probably use Poly-Fiber on this job rather than the Superflite I used on previous covers. I like the Superflite system as it has fewer steps and is easy to work with but (1) the glue is very MEK intensive and probably not at all healthy to breathe (2) While SF uses a 'flex agent' in the process the finish tends to crack in cold weather (3) it shines but it's heavier than other systems. I'd thought about using the Stewart System but seems there are some issues getting a good finish. The wings on my project are already done and looks like they used nitrate dope on them.

Mike

[Richard Murray]

Mike,

I too have used the local blasting company to clean parts and then washed them with FastEtch from Eastwood.com. This puts a phosphorus coating on the part in addition to cleaning any rust that might start so you can take several months before painting without the formation of surface rust. I used Poly-Fiber two part epoxy primer to paint the parts with and that was sufficient to prevent rust formation and a surface to glue fabric to.

Richard

[Champ Dreamer]

I used Poly Fiber's epoxy. Nice final surface. When it comes time to paint, I highly recommend using an airbrush on the tubing. Bought a decent one from Harbor Fright and it worked well, although you have to load it often. However, the vast majority of the paint you shoot ends up on the tubing, not the floor.

Brian Walker
N1197E
'46 7 A/C/ D/C About to fly !!

[Aerco]

I cleaned up my entire fuselage and every other metal part with a wire brush mounted in an angle grinder. Works great and you get to look at every inch of the airframe. Took about three days and my hands were buzzing for three more days after that. It's very controllable and you can be pretty gentle or aggressive as needed. Takes some contorting to get into all the corners, but it's a cheap way of doing it; I spent maybe $30 on brushes (Harbor Freight, of course!). They do shed wires and I learned to wear THICK gloves. I had some imbedded in my hands 1/2" deep, after penetrating ordinary gloves.

[Dennis]

mike,

Jerry got it right. it is hot, dirty and tedious work. No matter what type of protective clothing you have on, the lens will get dull causing you to miss spots. Plus the sand will permeate your clothing. You will get sand in every orffice, places you never thought possible. Then the nozzle will clog, then you run out of sand. about the time you get going again, the nozzle will clog again. Then it will start to rain.

I blasted one frame myself, the first time. The next time I had it done. It's worth the money.

Dennis

[MikeB]

Keep 'em coming guys. I need all the help/ideas I can get. What about using plain old everyday dope? Never used it but I think Bill Pancake still does and I'm always willing to learn something new. So far I'm almost convinced to hire the frame cleaning out.
Thanks,
Mike

[clipperfixer]

Just one more comment on the Black Diamond media. It absolutely does not dust up like most media. It will start to dust up after it gets contaminated with the rust and primer you blast off if you reuse it. but that is when I toss it.
Primers come in different varieties some seal, some don't. I used a Sherwin Williams mil spec zinc based primer. The company rep said that was all that was needed to prevent rust. I know some primers require a topcoat. I would make sure I read the primers data sheet to find out if it needs a topcoat.
Also, the blaster I posted about works so nice because of the media. It does not seem to suck up moisture like sand and other media do and therefore it did not clog the nozzle often. The Black Diamond media really is top notch.
I was going to let someone else blast mine. I just could not trust that they would be careful and I was afraid I was going to have an airframe blasted to hell.

Here's a picture of my cheapo set up. 23 hours of trigger time......A labor of love for sure.



This is what I started with:

[Paul Agaliotis]

Mike,
I tend to sand them down by hand, with paper and wire brush. Unless you can be 100% positive the guy with the blaster knows what he's doing, I'd stay away. Too many times I've seen tabs blown off and holes put in the tubes. It takes about 3 days to do the job but when you're done all of the tubing has had a very close inspection.
Once clean and repaired I use a catalyzed enamel, either urethane or epoxy. Copon was a good paint but I haven't seen it around for some time. Randolph makes a good epoxy and I have used it, the green. I'm starting to use a new brand called AKZO. It's nice and easy to use. Mix ratio is 1:1 and it's about $100 bucks a gallon. Takes about a gallon and most of it never hits the fuselage. I use a hopper type HVLP with a pint container. Narrow the fan pretty close to a circle and move fast to keep the sag out.
Spend a little extra time in the cabin area. Those tubes will be seen every time you fly it. Get a good coat on the lower longeron, this is where most of them will rust.
Paul

[MikeB]

Thanks Paul,
I'd say 90% of the fuselage tubing is in pretty good shape. Most of the rust is around some previous repairs at the tail end and at the clusters. Can't punch through it anyway. I'm still in the process of removing the wood former which are pretty rotten and badly deformed. I can't believe anyone would just shoot a new coat of paint on the fabric and let the rusted control surface tubing and damaged formers go but apparently that was the intention before I picked it up.

Apparently this also had a McDowell starter on it at one time as the pulleys and brackets are there. Too bad it was removed but I guess that was common and someone also replaced the nose bowl with a fiberglass one. Maybe the McDowell was standard on the 11CC's.

Mike

[Richard]

Is anyone using the poly-fiber epoxy on their tubing. I used it 10 years ago my my elevators, and now have some rust spots coming through the trailing edge fabric. I didn't put a top coat over the epoxy coating.
I miss the mil zinc chromate. That seemed to work well.

Richard