Lightweight Filler Powder Source?

Yes, this is a structural joint, and sag would not be welcome. A microfiber or short chop fiberglass would likely be a better choice. It has been a while since I have done this.

I built a canoe years ago and used West System powders, I thought I had some left, but I can't find the containers. I remember adding a crazy amount of powder to small batches of resin for fairing in the bulkheads, and smoothing for sanding. I also remember being asked why so much for a can of air!

When I lived near Lake Erie this stuff was everywhere for boat repair, looking for hens teeth since I am surrounded by dirt.

Wash with ammonia and water prior to sanding and you should have better performance with getting paints to stick to your epoxies. The curing process drives a waxy byproduct out of the resin and ammonia dissolves the wax.

Phil

For filler and fairing material, I bought a pound of microspheres from Aircraft Spruce. One purchase and you're set for life. But, as Ken noted, microballoons reduce the structural properties of epoxy.

Source: http://www.aircraftspruce.com/catalog/cmpages/bubbles.php?clickkey=23717

Phenolic microballoons are also a good filler; they will sand more easily than glass spheres, but will soften if used with some polyester finishing resins. They also add a reddish hue to the epoxy -- sometimes good in identifying the low spots.

If you're needing a filler and don't want to use or buy glass spheres, try DAP Lightweight Spackling compound. It's super lightweight, but it cannot be used as a very thin finishing filler. It can be found at most home improvement stores. I've used it quite a bit and have even thinned it with water and brushed it onto foam wings to fill the surface.

Chopped glass does not provide much fill, but will be significantly stronger.

That is looking more affordable.

Cotton flock? Sounds more friendly than fiberglass chop. Price is nice too.

Phil

How would balsa dust work? If you shaved down some scrap and mixed it in with the epoxy it should be plenty strong.

cribbs74 wrote:How would balsa dust work? If you shaved down some scrap and mixed it in with the epoxy it should be plenty strong.

I have done that with Testor's, which is celluloid, in the past. I did not reserve my sanding dust from this build since I thought I had a couple half-cans of different epoxy filler powders and did all my sanding outside.

Phil

If you don't have quick access to micro balloons, like previously mentioned DAP spackle works good, but again it depends what u are trying to do with it, wing fillets? soft 1/4" balsa triangle stock can also work.

I need to bond the wing to the profile fuselage and did a hack job making the hole. I need gap filling from naught to 1/4 inch. I said it was a hack job. Then I need to fair.

I will try to get some pictures up tomorrow, I found my card reader today.

Phil

pkrankow wrote:I need to bond the wing to the profile fuselage and did a hack job making the hole. I need gap filling from naught to 1/4 inch.

DAP Light Weight probably won't be a good choice for that application.

I think your best bet would be to cut a rectangular hole in your fuselage and fill it in with a close fitting piece of balsa, then re-cut your wing saddle. Or, cut your saddle slot first, then add the patch. This way, if the saddle doesn't fit well the first time, you can cut another before gluing in the patch.

pkrankow wrote: I need to bond the wing to the profile fuselage and did a hack job making the hole. I need gap filling from naught to 1/4 inch. I said it was a hack job. Then I need to fair.

Phil

Position the fuselage and glue balsa in everywhere you can..being careful to not disturb the fuselage position. After it has dried, then consider a filler. A 1/4" gap should be filled with balsa...for both weight and strength.

Good luck.

George

i never done that before.

You might tack wing in place, seal one side of gap with 1/4" triangle stock or masking tape, turn plane on side and fill gap with urethane glue (lazy guys epoxy), mist with spray bottle a little water so it foams/cures...bam done. BUT, experiment first cause it will really expand if you add too much water.

I didn't consider the urethane since I generally don't like it. I have a tube of "low foaming" white Gorilla glue, I'll lay up an experiment.

The wing fit is actually pretty good, except in the few places it is not. It makes contact or near contact at probably 50% of the joint, with all but a couple spots less than 1/8 inch gap in the other 50%. The fuse is sided with 1/16 plywood past the wing, so I won't be cutting into it. It is still a hack job I did.

I should have used a coping saw to cut the wing hole instead of using a razor knife is the final problem. A scroll saw is on the wishlist.

Andrew's link to Aircraft Spruce looks like the best deal I've ever seen. I think I'll just order from them.

Phil

I know what your saying, but once I got used to the characteristics of urethane glue it's pretty good stuff, close to epoxy, stronger then wood glue and has some flex to it like epoxy.

One time in a hurry building, I filled the saddle gap on a Sig Banshee with thick CA and kicker, it did seem to work, but I can't recommend doing that again.

You might just cut some 1/16"x1/2" balsa 'shims' and install length wise filling gaps.

http://www.qbond.net/

The strongest stuff I've ever come across
Sets instantly too.

Something that didn't click until now would also be baking soda with CA poured over it. That works well for filling in large gaps. Ken

Baby Powder (Talc) also works with epoxy, tite-bond, and several other wood glues and is fairly sandable

I have never bought the microballons or used it...mostly add talc, or baking soda, or sawdust to a very thick paste and rounded end of Popsicle stick to shape the fillet

Ken always has great advice so I went in search of Q-bond

Prices all over the place...cuz of where I live (out in the sticks) I prefer shop mail order with a couple of normal desires: Best price including tax and shipping

so far best I can find is $13.70 free shipping

http://www.ebay.com/itm/261100495949?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Q-Bond QB2 Bonding Adhesive With Filling Powder Kit. Black powder repairs and fills hard plastics, grills, radiators, distributor caps and much more. Grey powder is great for metal surfaces, motorcycle fairing, carburetors, aluminum, office equipment and more. The kit contains (1) bottle of black powder, (1) bottle of grey powder, (2) 10ml bottles of quick bonding ultra strong quality cyanoacrylate adhesive and (2) puncture pins to open the adhesive. Can be used as just an adhesive or with the reinforcing powder to repair almost anything. Adhesive is super strong so avoid contact with skin. Bonds to almost any surface within seconds. For more serious repairs there is the 2 part system of powder and adhesive with filling capabilities for cracks, holes or gaps that will allow the repaired piece to retain its original shape. The repairs can be grinded, filed, sanded, tapped and painted

My box is here!

Cotton flocking is, in a word, interesting. This stuff absorbs an amazing amount of epoxy. It definitely lightens the mix. I have a test batch curing, came out quite dry. I need to portion it carefully. I think it might be the best stuff to use... I'll see tomorrow.

Phil

The fit on the brown/pink one was worse than the yellow/white one. Near the nose the fit was worse than elsewhere on both, the 1/4 inch gap was in the same place at the LE on both.

So a pair of Zingers!



The sparse plans...
http://aeromaniacs.com/Zinger.htm

I also needed to use masking tape on the fuselage and wings since they were finished prior to assembly... alas, I must sand, mask and fix the brown. The yellow is OK.

Phil

Ken Cook wrote: Something that didn't click until now would also be baking soda with CA poured over it. That works well for filling in large gaps. Ken

From using baking soda and thin CA when there was no gap filling CA, this works well but is a BEAR to sand.

George