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Old Aug 01, 2014, 07:47 AM
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ForeverFlying's Avatar
Christiansburg, VA
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Bondo Anyone?

Hi Group,

Has anyone used this as an adhesive?

http://bondo.com/bondo-lightweight-filler-262.html

I wonder what is used as a filler to lighten it; fiberglass?

Is it sticky enough to bond well to foam or wood?

I need to join an EPP wing, and the joint is not closed, and needs some filler.

Thanks!
Mike
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Old Aug 01, 2014, 08:24 AM
The Junk Man
Jacksonville, Florida
Joined Jul 2006
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Bondo will melt any polystyrene based foam, i.e., $Tree, Fan Fold, EPS (Styrofoam), etc.

Never used EPP so do not know if it is compatible or not.

Tom
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Old Aug 01, 2014, 09:11 AM
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Aurora Municipal, Illinois, United States
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It has the consistency of peanut butter. It works well with hardwood but wouldn't be a good choice for foam. Using it on balsa probably wouldn't work because it cures harder than the balsa and would be tough to sand.

I've used lightweight spackle on foam to fill the rough texture before glassing. Sands easily and is pretty cheap.
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Old Aug 01, 2014, 09:25 AM
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Actually, that sounds pretty good. I can be careful not to overfill.
What I am now concerned about is the working time. It's only 3 to 5 min. For something like this, I think I need around 15min min.
I am looking into using the epoxy resin in a can.
http://bondo.com/products/household/...sin-20122.html
I figure I can mix micro ballons in to thicken it up.
I hate paying big bucks for a little dab of epoxy. This is a whole quart for the same price as 4 oz of many!
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Old Aug 01, 2014, 11:39 AM
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Canada, ON, Cottam
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I use it to bond the oak onto the fiberglass in my Street Rods. Works good. I think my fiberglass guy sold a powder to mix with polyester resin that basically makes the bondo. I am not sure if it was microballoons, although he sold that too, as well as the more expensive phenolic microballoons. The is also another brown foam that is used for home sheathing, maybe cellulose, that withstands polyester resin base. It has different properties than the regular foams used in models. Not sure if a hotwire works or gasoline will dissolve it if used for a one off mold. There is also a Corvette type glue that is likely polyester based. Naturally it is more money than the bondo.
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Old Aug 01, 2014, 12:33 PM
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Sure it works great on fibeglass, but if you use it on foam , you won't have much left-- it will melt it. And you'll be damned sorry you did!!
. don't ask me how I know..

Quote:
I need to join an EPP wing, and the joint is not closed, and needs some filler.
As was mentioned, just use a lightweight filler..

As for Bondo you mentioned- http://bondo.com/bondo-lightweight-filler-262.html - I use it myself, But on foam, I have given it a coat of epoxy first-- it won't melt it then. Foam has be be sealed really good.

But this stuff-- http://bondo.com/products/household/...sin-20122.html -- never use it on foam!!
EPoxy only..
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Old Aug 01, 2014, 12:39 PM
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It melts EPP?
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Old Aug 01, 2014, 12:57 PM
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Yes, it's a Polyester Resin--, not epoxy.
A Polyester Resin to foam is like a match to gas!!

I used some Polyester based filler on a foam plug I was making, wrecked a great deal of it.. Never did finish it, too much work to repair it.

If you need to glue the wing on, just use epoxy-- and get a good lightweight filler. I like the Red Devil " one time" lightweight spackle. Other brands I would think are similar. When you pick it up and it feels like it's empty-- you've got the right stuff..

Quote:
I hate paying big bucks for a little dab of epoxy. This is a whole quart for the same price as 4 oz of many!
Pay now or PAY later!! I'll bet a new plane is more expensive than some epoxy!!
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Old Aug 01, 2014, 03:10 PM
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I like the polyurethane glue for foam, cheaper, sorry, less expensive than epoxy, more flexible, and lighter because it foams up, and there is air in it. Good for skins too with a clamped foam rubber in between. If you poke holes in, say a wing joint or landing gear cutout, the PU expands into the foam too.
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Old Aug 01, 2014, 06:28 PM
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United States, KY, Taylorsville
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I use polyester resin (Bondo) all of the time. I just finished installing the windows and their attendant frames to my Taylor J-2 Cub this morning. I made the frames from home made G10 stock using this resin, 4 oz cloth and Q-cells. I also make parts using this smelly stuff. It takes about an hour to cure and it shrinks some. I wouldn't recommend building airframes with it.

Seal blue foam plugs with wood glue then you can glass them using Bondo. It's how I make plugs so as to make molds for making parts.
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Old Aug 01, 2014, 07:59 PM
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The 'Wack, BC, Canada
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ARUP, are you sure it was Bondo? As in the auto body filler? Or a Bondo brand laminating resin? The body filler stuff would be a real bugger to get it to saturate through some layers of cloth or matt.
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Old Aug 02, 2014, 03:38 PM
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United States, CA, Norco
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Bondo or body filler would not be a substitute for glue. Especially on EPP or EPO foam

Use 2 part epoxy for the glue joint and a mixture of epoxy and micro-balloons for a filler.

As far as polyurethane glues are concerned the foaming action or air bubbles in the glue don't make for a good structural joint and IMO is not a good idea.

The same goes for using fillers in Epoxy. Typically adding fillers to epoxy weaken its use for structural purposes.

That being said you're EPP wing joint is probably not going to see huge stresses at least those that would cause an epoxy glued joint to fail. So the polyurethane glue would work fine. The EPP wings will fail long before the polyu glued joint does.
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Old Aug 05, 2014, 12:22 AM
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No- It won't make a good glue for EPP. Its lightweight filler is probably microballoons

FWIW Bondo won't melt EPP- not much will. EPS, on the other had will melt in the presence of Bondo/Polyester.

To glue EPP get some Goop or E-6000. Works great, stays flexible for decades.
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Old Aug 05, 2014, 01:19 PM
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USA, WI, Milwaukee
Joined Apr 1999
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I used Goop on a Multiplex Twinstar once for repairs...
ONCE
Whatever kind of foam they are made of, the Goop just ate it right up...
Live and learn...
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