Hi Fred,
I'm sure others will chime in but my two cents are this. Yes you may be
over complicating it. I tried the dry micro in some areas and found it
to be too much epoxy or too hard to sand compared to the structure or
the expancel. After several attempts such as you are doing I just
resigned to roughing everything and applying the expancel thick. Then
blocking it all back down with a large block. In the long run it was
easier. I can't speak for the Super Fill but others I know love the
stuff. For me it was just economics and I had plenty of the expancel
so I used it.
Put it on thick so only one application is needed. Block it down till
you just start to see the weave in spots. If you have any low areas hit
them again with a light sand and more fill. Mixing micro with other
fill material will only cause more work as they sand at different
rates. I hope this helps.
Best Regards,
Jeff R.
A258 - N128LJ / Gold Rush 150 hours and climbing slowly.
On Sep 15, 2008, at 6:47 PM, Fred Klein wrote:
>
> Say guys...if you can take a walk down memory lane with me for a few
> moments, I'd appreciate some feedback.
>
> The other day, while looking for trouble (i.e., a reasonable next step
> in my build) I set myself up to skim some dry micro to fill the
> trailing edge depressions where the top and bottom skins are bonded
> together, thinking that it would be just an afternoon's job which,
> after cure, would be followed by some block sanding to knock down the
> high spots, and followed by the application of filler over the entire
> panels (flaps, ailerons, and trim tabs) to cover the weave. (For this,
> I'm planning on using Poly-Fiber's SuperFil rather than Expancel.)
>
> What I've found however, is that filling those depressions is a bit
> more of a job than I'd anticipated. Notwithstanding using what I
> thought was the stiffest possible mix of micro, I find myself with
> numerous low spots thus requiring 2nd and in some cases 3rd
> applications of the micro in order to bring those trailing edge
> depressions up to the plane of the airfoils. Between coats, I've used
> small bits of 150 grit sandpaper around a forefinger so that the
> subsequent coat of micro would have a better bond than to simply apply
> it over the (glossy) low areas. I've been working under the assumption
> that these trailing edges must be dealt with completely before
> squeegying on the filler to fill the glass weave over the foam.
>
> I've also been careful when knocking down the high spots to not abrade
> the glass fibers on adjacent areas.
>
> Given that each surface has two sides and I've found that the micro
> must be applied separately to each side (in multiple coats w/
> intervening cure cycles), at this point I'm sitting here wondering:
>
> - Have I made this more complicated than it need be?
>
> - Am I missing something here?
>
> Lookin for either reassurance or a cautionary "heads up",
>
> Fred
> A194
>
>
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