I can't remember where I got this one, but it works every time. Instead of sanding the wing saddle to get a perfect match to the wing try this...

1. Cover the wing where it will contact the saddle with seran wrap or whatever that thin plastic stuff in the kitchen is called.

2. Mix up a batch of 30 min epoxy and add some micro balloons in a 2:1 ratio. 2 parts MB to 1 part mixed epoxy.

3. Lay a bead about a 1/8 inch bead along the saddle, too much is okay here.

4. Attach the wing to the fusilage using the rubber bands, bolts, or small sand bag.

5. Let it sit about an hour or so till the epoxy sets but is not yet rock hard.

6. Remove the wing and plastic, trim the excess, and voila!, a perfect wing saddle.

Key things to remember... Do this before covering, and don't forget the seran wrap. Guess what happens if you forget about the seran wrap.

I still can't remember who I got this tip from, but if you're still out there, Thanks again.

I do the same thing, but I use Waxed Paper and Wood Filler.

Good idea.

However, I use wing saddle foam tape which seems to work pretty well, and provides a good seal againts fuel / oil getting into the radio compartment.

-David C.

I do something similar... I use West systems and micro ballons(cures much harder). When the wing and fuse is finished(painted or covered) I bare the wing saddle, wax the wing area with parting wax, mix up epoxy/balloons to a thick consistency and apply a liberal amount to saddle. I wax the bolts and attach wing and perform final incidence checks. Let dry 24 hours and then pop off wing. Start at a corner and work it loose and the whole wing will then pop off. You will be left with a perfect copy of the wing on your saddle including any covering/finishing imperfections! You can clean up the excess drooling down the fuse while wet with paper towls damp with de-natured alcohol. On a painted fuse you can do this prior to fuse being painted and then mask the saddle prior to painting.

I do the same but with silicone. you know the drill seran wrap on wing silicone clear on fus leave overnight wala perfect seat

Yep, silicon and sarahn wrap. flexible too!! and sticks to Monokote!

Hey all...I've done this also, but I always put in some cabosil to keep the epoxy/micro ballon mixture from running. Tom

I just keep adding micro balloons until I get a consistency of thick peanut butter.
This technique has worked fine for me. Running of the mixture has never been an issue.

Is there a good reason for cabosil in this application apart from thickening?
Seems to me adding this instead of more micro balloons just increases the density of the mixture, in an application where structural strength is not particularly critical.

Marty, I don't think micro-ballons will stiffen the epoxy. I use system three and I need to add the cabosil to stiffen the mixture. The "manual " that comes with the system three recommends using cabosil. I tried it without, using a tremendous amount of micro-balloons and it wouldn't stiffen up. It is my understanding that the mico-balloons makes the epoxy lighter and sandable and the cabosil makes it stiffer. Tom

Cabosil will work but to me it doesn't sand very well. Micro-balloons will definitely thicken the mixture and prevent it from running. You just aren't adding enough. It's astounding how much microballoons can be added to a small amount of epoxy. You can get it as thick as peanut butter if you want to (great dent filler!).

Yep...

You're both right. Cabosil, in small amounts, will thicken the epoxy. That's good for bonding and even some penetration. But for something cosemetic, I'd rather sand a highly "infused" mixture of epoxy and microballoons than to sand mostly epoxy with a little Cabosil.

PS>The wing saddle...
I typically make the top of the wing fairing with epoxy/microballoons. But where is contacts the wing, (the "not visible" part) I use silicone.

This sounds like an awesome technique .
( embarrassing admision - I had never heard of microballoons till
i read this thread - hehe I own a bottle now though ) and
you guys seem to talking about variations on a theme on
methods - here is my situation. I own a GP big stik 60 that
had a battery pack die at 80 ft 60mph and decided to do an
Emu impression which splintered the wing [X(]. I was able to rebuild
the fuse and my LHS had a Ultra Stik 60 wing with an almost identical
chord ( a tad shorter but creative woodworking and repositioning the
hold down plates made it fit nice n' snug) but the saddle did need a
little work. Using the trusty dremel and s/paper I got close but still
have a couple of little gaps. I was originally going to use foam tape but am
going to try this instead - Here is my question what is the best way to make
sure I have the wing on evenly and not a little slanted left or right as
I got a wee bit over zealos w/the s/paper and need to slightly build up one
side over the other and good tips you guys might be able to supply
for getting the wing nice and even ? Best I can figure is to measure w/tip
to w/tip on a flat surface build up one side, dry then repeat - Any easier
methods ? Just wondering

Christopher

You have the right idea.

Immobilize the fuselage on a large flat surface, and dry fit the wing.
Measure carefully to ensure a level, square fit.
If the wing is not level, adjust by building up the wing saddle with thin balsa shims and CA.
Don't worry about small gaps, you'll be filling them in anyway. Measure again and repeat.
Once everything is aligned properly, mark the wing position so you can put it back the same.

Now use the the epoxy and micro balloons.
Good luck with your project. This is an easy task. You'll be pleased with the results.

Have used foam strips for many years without any problems, but remembering that "Better is the enemy of Good Enough", I tried the silicone/saran wrap approach on my last ARF (a VMAR Texan II, but that is another story). Came out like a dream but for one small detail; the silicone sticks less to the covering than it did to the saran wrap. For the moment the wing is holding the silicone in place. My next try will be to punch some holes in the covering to give the silicone a grip. Hope I don't have to cut away the covering from the saddle because you know that will be the first place the covering will start to lift. I suppose I could go back to the foam tape, but that would be like surrendering in the face of the enemy, wouldn't it?

I usually use micro-balloons and epoxy, but will use silicone at times. The technique varies slightly depending on what you use. I did a how-to of the technique and posted it on my site last year.

This is something someone showed me many years ago. It certainly wasn't my original idea, but I thought it would be helpful to other builders so I did a photo sequence and posted it.

Perfect Wing Saddles

Hey everybody,

The posting above led me to Paul's (CafeenMan) web site, which is very nicely done, with a lot of great photos and tips. If you haven't already done it, check out this site at http://www.airfieldmodels.com

Yea no more wing saddle gaps My 1st foray with micro baloons and epoxy
went well , one thing I did find though which I will pass on is make sure
if you use seran wrap it is nice and TAUT on the wing otherwise you get
a lovely imprint of the ripples in the plastic. Being a belt and suspenders
kind of guy I also used foam tape to finish after covering which gives it
a nice tight fit and also looks a little better ( unrelted advice the glue
backing on foam tape lifts off the second it even smells glow fuel so
I always attach it on the covering using CA ) Thanks for all the helpful
advice guys