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dereckbc 07-02-2014 02:34 AM

Foam Repair Guru's, Need Help
 
2 Attachment(s)
Crashed my EXTRA 300 into power lines, and one of the power lines cut into one wing. What is the best way to fix this??? THX

Dereck

fhhuber 07-02-2014 02:39 AM

Gorilla Glue "Dries White". It will expand and fill the gap. Then shave off excess, sand and touch up the paint.


Then... don't fly near power lines.

dereckbc 07-02-2014 02:47 AM

I have Gorilla Glue I use for wood working. Will it fill a gap that big? Or should I mix in some foam with it to make a paste?

thepiper92 07-02-2014 02:57 AM

That sounds like wood glue, not just standard gorilla glue. Gorilla glue should be viscous enough to fill in well.

kyleservicetech 07-02-2014 03:24 AM

Quote:

Originally Posted by dereckbc (Post 951998)
Crashed my EXTRA 300 into power lines, and one of the power lines cut into one wing. What is the best way to fix this??? THX

Dereck

Check out Red Devil Onetime Lightweight Spackling, available at your local hardware store. A one pint container only weighs about 6 ounces or so. This stuff has little mechanical strength, but is excellent for filling holes and dents, especially in foam areas. The spackling has the consistency real thin peanut butter. It stays exactly how you put it on, and doesn't sag.

Just wet your finger, and very slightly moisten the area to be patched up. Then build up this spackling with perhaps no more than a 1/4 inch or so at a time. Doing that, you can fill some pretty big holes or dents. Make the final application higher than the surrounding area, since this spackling is very easy to sand.

I've even toughened very small areas up a bit with a drop or three of CA, but try that trick on scrap material first. And, give it 24 hours to dry first.

fhhuber 07-02-2014 03:28 AM

Gorilla Dries White

Try that stuff.

Not Gorilla Wood Glue

dereckbc 07-02-2014 03:49 AM

1 Attachment(s)
This is what I have. It dries yellow, but note the label Bonds Wood, Stone, Metal, FOAM, Glass & More. It just dries yellow and is very thick viscous stuff.
Quote:

Originally Posted by fhhuber (Post 952003)


fhhuber 07-02-2014 04:16 AM

The yellow foaming Gorila glue will work but not as nicely as the "Dries White"

Before the white, quick drying version came out I used to recommend mixing 4 parts of the Gorilla foaming polyurethane with 1 part Elmer's School Glue to make a faster setting more actively foaming filler-glue. to deal with missing chunks in foam models. Without adding water the older version does not foam up as well.
Just adding water, the water tended to separate, the white glue mixes with the poly glue very well and does not separate.
This can expand a surprising amount... but unlike expanding foam insulation in a can it does not expand with enough pressure to blow apart a fuselage if you fill a typical balsa-wood box fuselage with the mix.

I've done a lot of experimenting with glues and fillers for all sorts of purposes...

thepiper92 07-02-2014 04:29 AM

Quote:

Originally Posted by dereckbc (Post 952004)
This is what I have. It dries yellow, but note the label Bonds Wood, Stone, Metal, FOAM, Glass & More. It just dries yellow and is very thick viscous stuff.

It would hold, but wood glue dries rock solid. Foam isn't stiff like wood glue, so that could lead to further damage for it creates a stress point. Plus it dries an ugly yellow. You want a glue that holds but is somewhat flexible.

solentlife 07-02-2014 08:10 AM

Local Home Depot / B&Q / Lowes / Maijas Damas ... that now covers USA .. UK and Latvia ...

They have POLYURETHANE wood glue. It is the same as Gorilla Glue ... comes in both forms ........ Interior (White) and Exterior (Brown).

For the wing-ding of OP ... as said - white GG .. or I would say .. White PU glue from DIY store at 1/4 price and 3x the quantity.

Simple ... very light spray of water .. more a mist ... then squirt some PU in there ... let it expand - it has an incredible expansion coefficient ... leave it for 1/2 day ... then sharp knife ... carve excess away. Leave it overnight ... then sand and paint.

If the ding is bigger - then cut a piece of foam to fit ... usually I would cut out a square or straight so the repair piece going in fairs in nice ... PU glue it in .. cut / sand .. paint.

Don't use CA .. Epoxy or standard PVA wood glue. These leave hard glue lines that you will have great difficulty smoothing out.

Nigel

BroncoSquid 07-02-2014 03:56 PM

Carefull using the expanding glue, I used it on a fuse once, it pushed the foam apart then hardened. Make sure you use tape or something to keep the wing braced in the shape you want.

solentlife 07-02-2014 04:03 PM

Quote:

Originally Posted by BroncoSquid (Post 952033)
Carefull using the expanding glue, I used it on a fuse once, it pushed the foam apart then hardened. Make sure you use tape or something to keep the wing braced in the shape you want.


True - but usually happens because the foaming action is restricted in where it can go ...

With a slit in a wing ... the amount of foaming action will exit front top and bottom ... quite easily.
I do at times strap a wing down if the area to fill is extensive ... but then that's only when I haven't suitable foam piece to insert.

One trick with PU glue ... you can actually control it's expansion and what results. You can tape over an area and create a smooth surface ... but always allow an exit point ... and this is handy when filling inside a box fuselage etc. - you can make the foaming exit through a hole in fuse side or into fuse ... as you decide.

If you do not spray with water first - the action of foaming seems to be slower ... and more dense ...
Spraying with water the areas to join and then light mist of water onto the glue itself - can expand the glue even more to a lighter mix ...

Nigel

dereckbc 07-02-2014 06:02 PM

1 Attachment(s)
Is this the STUFF.

solentlife 07-02-2014 08:47 PM

Quote:

Originally Posted by dereckbc (Post 952041)
Is this the STUFF.

Yes. - That's the white interior grade that is fine for us ...

You then can get another grade which is the Brown - it is exterior and waterproof ... even to seawater.

Here's Gorilla Glue Brown vs Generic PU Wood Glue ... BOTH same product ...

http://i6.photobucket.com/albums/y24...psc73bee7a.jpg

The Larger bottle being less than half the price of the GG ...

It is also available in white version at similar over counter at your local Home Depot store lower price !

Before you go at your wing ... get yourself a small sprayer - like the ones gardeners use to spray the leaves of roses etc. That will give a fine mist water spray for your PU gluing...
Also don't forget that you don't actually need to spray water ... moisture in the air will set it off ... but slowly.

If you laminate with it or joint - you must keep it pressed or taped fully ... to stop it expanding and forcing open the joint.

Before doing your wing - experiment to see it's full effects ..

Nigel

Abuelo 07-02-2014 09:07 PM

+1 on the Gorilla White Glue. Huber's got you covered.

If you want a more paste-like, or if you want something lighter than just the glue, try Durham's Water Putty (red, white, and yellow round can) and small amount of water mixed into the glue. Not a lot of working time as the water is there at the get-go but if you can enclose the repair with tape it will work well.

What will also work well is Gorilla White Glue mixed into diatomaceous earth. DE is available either as a pesticide or as swimming pool filter medium and is light and white. I've mixed them up for fillets then sanded to shape but this leaves a slightly rough surface. Just don't get the DE into your eyes as it is crushed shells of calcium carbonate.; insects will ingest and have their innards shredded.

solentlife 07-02-2014 09:30 PM

Quote:

Originally Posted by thepiper92 (Post 952007)
It would hold, but wood glue dries rock solid. Foam isn't stiff like wood glue, so that could lead to further damage for it creates a stress point. Plus it dries an ugly yellow. You want a glue that holds but is somewhat flexible.

Piper - the Wood Glue he showed is Gorilla Glue Exterior .......... the brown version. It is not the PVA or Gut Glue that dries rock solid. In fact PVA is a flexible glue for wood structures and my preferred for balsa etc.

Nigel

thepiper92 07-03-2014 01:41 AM

So it would work well then. I've never used the gorilla wood glue myself, but drying yellow I just thought wood glue. Why do you prefer the PVA glue, does it hold as well as wood glue.

solentlife 07-03-2014 06:16 AM

Quote:

Originally Posted by thepiper92 (Post 952078)
So it would work well then. I've never used the gorilla wood glue myself, but drying yellow I just thought wood glue. Why do you prefer the PVA glue, does it hold as well as wood glue.

Hi Piper ...

GG / PU is actually primarily Wood Glue.

I prefer PVA for wood models because of the flexibility of the glue. Epoxy is heavy and adds weight .. plus it's rock hard.
CA is the Devils tool and in my view not for general wood building - it creates hard stress points.

Lets be honest - most people are looking for a fast joint .. so they grab the CA or 5 min epoxy ....... but they ignore the consequences.

Take two pieces of spar .. overlap the joint and zap it with CA. watch the CA soak in and spread ... the bloom spreading out from the joint. Now bend it and see where it breaks. Usually right at the end of the CA with no give in the joint at all as it bends.

Now do same with PVA .......... the joint will give and spar will bend before breaking.

PVA also creates a vibration / sound damper .. the glue being non-solid is like adding a bit of foam in the joint. CA and so on - carries the sound vibes through the structure ... but PVA literally softens it and reduces it.

I have built many models with CA ... the old Pilot kits were so good on Die-cutting - you could literally slot together in hand and zap with CA ... But I always paid a price later when I crashed or dinged the model.

I never use any CA on any foam model ... foam safe or not. PVA also is not suitable for foam models ..

I guess it's old school vs new !!

Nigel

thepiper92 07-03-2014 07:32 AM

Can't stand CA myself. I had to use the stuff liberally for gluing of tires on rc cars, after most manufacturers became cheap and decided to get rid of beadlocks (they say it is weight, but my one rc car actually came with beadlocks and has no issues going over any highway speed limit here). It is that fast bond that I hate; something isn't aligned...well it's gonna stay that way. I have never used it for any builds, or on my foam planes, Uhu Por and now Canopy Glue is what I fix the foam with. Uhu Por works very well, but has a habit is being stringy and I find it can give white foam a yellow tinge as well as attracts dust easily. Uhu Pop, however, has a nice flexible hold. Canopy Glue has an even better hold, still very flexible, but it is runny. If filling in a dent, it does work well, as it has a high enough surface tension to hold a small amount. For breaks where the pieces are intact, it will repair with no sign of damage overall, other than say surface paint layers on the foam itself.

For balsa, I see why it would be good to have some flex I suppose, but I feel the idea is to build a model with as little flex as possible.

fhhuber 07-03-2014 07:50 AM

Depends on the purpose of the model... and the type of joint being made. Sometimes you want a very stiff aircraft and sometimes flexibility is a good thing.

Sometimes you want one part of the aircraft extremely rigid and another part to be flexible...

This is why I will often use up to 10 different glues (white "school" glue, Alphatic resin, thin/med/thick CA, PU, assorted epoxies, contact cements and even Ambroid ) in one wooden framed model. Each joint gets the right glue for the loads that it will have to handle.

EPO foam models demand their own particular list of appropriate glues... Other foams may use some of the same glues and may be destroyed by a glue that is just fine for EPO.

The right glue for the right job gets you the best strength for the least weight.

solentlife 07-03-2014 12:32 PM

True ... right glue for job ...

Problem is with todays generation - the CA disease has taken hold.

One of the old ways which has many of todays new modellers surprised is the use of the old Contact Adhesive in wood models ..........

When fitting doublers to fuselage sides - Contact Glue was the best and preferred glue ... because it allowed the fuselage side to bend to required shape and still hold the doublers secure.

My use of PVA is even in those models that require more stiffness ......... why ? Crash one and see !!

Nigel

thepiper92 07-03-2014 05:01 PM

I find the titebond wood glue that dries clear works well. It seems a little more rubbery to the touch when it's dry compared to yellow wood glue.

kyleservicetech 07-03-2014 06:14 PM

Quote:

Originally Posted by thepiper92 (Post 952128)
I find the titebond wood glue that dries clear works well. It seems a little more rubbery to the touch when it's dry compared to yellow wood glue.

+1 on Titebond. 90 percent of my models are glued with this stuff.

Some years ago I ran tests with CA and titebond. It turned out after the titebond had dried tight bond was lighter in weight.

Do be careful with yellow glues and foam though. These yellow glues require air to dry and they may never dry inside a foam airplane part.

RayDF 07-04-2014 08:49 PM

Acrylic paint good for E-flite "Z-Foam"?
 
I wonder if you think that acrylic paint (water-based) would be good for painting the Z-Foam used in the E-Flite Apprentice S 15e? I happen to have a tube of such paint from my wife's painting classes, and it's the right yellow color (for the underside of the wing, so it's easier to spot from the ground.)

Thanks!

fhhuber 07-04-2014 09:42 PM

It will work but you'd need to use an airbrush in order to apply it thin enough to keep weight down.


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