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flox vs micro balloons?

dbhill916

Well Known Member
Hi all,

I've learned a lot about sheet metal and rivets, etc., but still have much to learn about fiberglass.

I am repairing some mis-drilled holes in my wheel pants. Is it an acceptable repair to mix some epoxy & filler and use that to fill in the holes if the correct holes will later be drilled about 1/4" away?

Should I use balloons (what I'm familiar with) or flox?

Thanks for any pointers,
-dbh
 
Flox adds a structual component to the resin. Think of this as lots of little fibers that get bonded in place.
Micro-ballons are tiny spheres that don't add any structural strength, but instead are lightweight filler that can easily be sanded.

If you are filling drilled holes, I would just put down a couple of layers of fiberglass cloth, then after that cures you can fill in the imperfections with micro.
 
Flox adds a great deal of tensile strength to the epoxy, micro adds no strength, and for a given volume is much lighter than pure epoxy or flox mix. It's used to make the micro thicker and lighter.
You can add some flox to a micro mix if you think some additional strength is needed. For your hole repairs I'd use a flox.
Tim Andres
 
use flox but..

Use flox as discussed but just make sure it is smooth on the outside cause its way harder to sand off than micro, I usually leave it a little mounded on the inside of the hole, not much just enough to give strength, but its smooth on the outside before curing.
 
You could also use Milled fiber or Cabasil. It's stronger than Flox which is milled cotton. Micro is great for a light weight filler but not good for anything structural. Also any of these can me mixed for a lighter less structural brew, depending on your needs.
 
If the hole isn't any larger than 1/8", I'd put some packing tape on a small piece of scrap aluminum and tape it (tape side down) over the hole on the outside and fill the hole with flox. If you do it right, you won't have to sand it much because the aluminum will fit flush with the outside skin.

Cabosil will not add strength, it only makes the resin thicker. Either cotton flox or milled fiberglass will add strength. If the hole is larger than 1/8", I'd lay a couple plies of fiberglass inside the wheel pant and then fill from the outside after the fiberglass has cured. You'd have to sand from the outside in this case, but it's not that bad. I've done this many times.
 
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