Fiberglass technique Help

[bobmarkert]

My fairing rough work is done and now I want to work on the finish fiberglass. My question is:

If there is an uneven transition between parts do I start with a thin layer of glass cloth then finish with SuperFil / and or epoxy and microballoons on top or should I put the filler down first and then glass cloth on top. All suggestions appreciated.





Thank you

[rleffler]

I put the filler on first, then the glass strips. It still required a bit more filler/micro afterwards. My thought was that the initial filler added a bit more support (although not structural).

[rbibb]

Just do whatever Dan Horton says...

[DanH]

I assume you're interested in filling the seam between the polyester/glass empennage tip and the aluminum.

I'm 4-1/2 years and 450 hours into an experiment...no glass fabric over that seam.

The flange on the empennage tip, and the adjacent surface area, was sanded to remove the gel coat. The underside of the aluminum was sanded for tooth. Structural adhesive was applied to the flange, the parts were assembled with clecos, and the rivets were installed while the adhesive was still wet. The goal was a firm foundation, i.e. no relative movement between the dissimilar materials. The seam was later filled with ordinary dry micro, which seems to be doing fine. There are no paint cracks at this time.

If you wish to add a ply or two of glass cloth, fill the seam first, using dry dry micro.

Work on closing and finishing the ends of the tips before you fill long seam. Mount the elevator on the stabilizer hinges, adjust them properly, and trim the ends of the tips for a suitable gap. Now fixate the elevator in trail with the stab, which will allow you to match up the profiles of the stab and elevator tips. They don't necessarily match right out of the box.

[MeAndMyToys]

Dan, what did you use for "structural adhesive"? What did you use for support in the open tip?

[DanH]

Originally Posted by MeAndMyToys

Dan, what did you use for "structural adhesive"? What did you use for support in the open tip?

Probably Hysol 9430. T88 would probably work fine too.

Closed the end with 1/16" birch plywood, glassed on both sides. Do a flox filet on the back.

[MeAndMyToys]

Thanks Dan, looking forward to using alot of your advice on fiberglass and cooling in the near future.

[bobmarkert]

Thanks Dan,
One more question please
when do I use Epoxy/Flox, When do I use epoxy/microballons, and when do I use SuperFil?

Ok that was really three!

Thanks
Bob

[MikeyDale]

I believe Dan will say, micro balloons and super fill are just fillers and are used when you do not need any structural strength. These are easier to sand. Flox and epoxy mix is used when you need some structural strength and is much harder to sand unless you catch it early in the cure process when it is "green" or not fully cured. You can do a mixture of flox and micro balloons to make it a little easier to sand and have a little strength also...I purchased a package of super fill and used it building my plane but if I had to do it over again I would have spent that money on something else. Dry micro mix does the same thing as super fill. Spend that money on a can of fast hardener for your epoxy kit so you can have a faster cure on small batches and you can sand earlier. A choice of fast hardener and slow hardener will give you much more versatility with your mixes.

[bobmarkert]

Thanks Mike. I only use the fast hardener (205). Both you and Dan said "dry micro" Am I correct that that that means a very thick mixture paste made buy adding a lot of micro to the epoxy so it is not runny at all?
Bob