Missileman

I have brought some of my building technics from my high power rocket habit to rc.
One of these technics is the use of epoxy fillers.
First off start with good quality epoxy. I use West Systems myself but there are other good ones out there.(note: do not use fillers with 50/50 mix hobby store epoxy, it just makes a mess)
Colloidal silica- after mixing your epoxy stir in the silica until you have a mayanais consistancy (note- volume will drastically increase so only use small batches of epoxy) This increases the strength of the epoxy and can be applied without worrying about runs. Good for firewall and landing gear blocks, ect...
Micro balloons- this will give you a lightweight fillet that sands easily, Mix the same as the silica. Good for beefing up areas (like rudder mounting) where you want to keep the weight down (note: micro balloons are weaker than colloidal silica so avoid using in high stress areas)

tashley

My Feedback: (9)

Great tip! How did you know I am getting ready to use a filled mix to form a fillet on the former rings at cowl on my 50cc Yak?
One question though, what is your reason for using the West System epoxy? I have it on hand in my shop but I was just wondering if you would elaborate.

Missileman

Sure,
The West Systems epoxy (or other 6 to 1 mix epoxies) are stronger and mix well with fillers.
All epoxies in terms of resin to hardener are 6 to 1 or 5 to 1 mixes.
Hobby shop 50/50 mix epoxies achieve this mix by adding fillers to the hardener (makes it easier for the newbie modeler but is weaker and does not mix well with fillers)
Another reason I use it is because I have a gallon of resin and a quart of hardener in my garage

IronCross

Where do you get this stuff at... Do you have a web address ?... Sounds like good stuff..

N1EDM

My Feedback: (2)

Is this the same stuff that you buy at West Marine (www.westmarine.com) for repairing fiberglass boats?

Bob

Missileman

I get mine from Commonwealth displays http://www.commonwealth.net/rocketst...tryframes.html
But it is local so I don't mail order from them.
Here is a link to the West Systems website
http://www.westsystem.com/
West System and other good epoxies can be had at marinas but be prepared to pay a premium price.

Chip_Mull

My Feedback: (1)

Check out this link: http://www.stits.com/pfdocuments/epoxy.html It's atwo part epoxy filler that's lighter than anything you've used and easy to sand.

Super-Lightweight Epoxy Filler
Only 3.68 pounds per gallon -- Bondo is about 10!
Epoxy Tough
Will Not Shrink or Crack!
SUPER-EASY Sanding
Great for Composites, Aluminum, Wood, and much more
Under $20 for a Quart Kit!

To order: http://www.stits.com/store/msc.html scroll to the bottom of the page.

It's easier than West Systems, lighter than West Systems and sands better.

tommy s

My Feedback: (55)

I use an epoxy that I get from a golf company called Leaderboard Golf that is
made for glueing the shafts in golf clubs. It is super strong, fast curing, doesn't
get brittle with age, and is available in bulk sizes at a cost savings. If you buy
large sizes of any epoxy it will last longer if you keep it in the refrigerator.
(Don't let the kids drink it !!! )

tommy s

da Rock

Good thread...........

But...... It's easy to buy Micro Balloons. Most of it's marked as such. I think I got at least 3 different brands in the shop.

But how do you find the silica and where? I've yet to see anything with silica in the contents.

Thanks in advance to anyone will fill in what brands or where to find the silica filler. TIA again........

Missileman

I am sure there must be other brands but here is a link foe west systems coloidal silica.
http://www.jamestowndistributors.com...oloidal.Silica
I should have mentioned before, some people also use chopped fibreglass or carbon fibre as fillers, both methods add strength.

jetpack

My Feedback: (1)

I know everyone's looking for lightweight fillers, but I am a boat builder and the amount of filler we need sometimes does not need to be lightweight more than it needs to be visually correct when filling outside joints that will stay clear-coated.

Instead of commercial epoxy fillers (=expensive) or saw dust (=coarse) I use wheat flour. You know, the stuff for bread dough.

It is:

1. Close to wood as a material.
2. Much finer than wood dust from sawing or sanding, so creates smoother surfaces.
3. Almost wood color (light).
4. Available everywhere.
5. Very cheap.
6. Ecological. When You need to get rid of the excess, just bake a bread and eat it.

Further hint:

If You need to match filler color to wood color, try using other types of flour also: rye, barley, corn...
And try coloring it with ground cinnamon, ginger...

Tired Old Man

My Feedback: (1)

Another source of good epoxies (System Three, a two-one mix) is Fiberglass Supply in Bingen, Washington. Google them for the website. They carry all the glass, carbon fiber, and kevlar you may need, along with cabosil (glass beads/powder, similar to microballons) milled glass fiber in several sizes, which is great for making strong fillets that won't crack later. The cabosil can be used the same way, and to make epoxy fills that will not run or sag when applied. They also stock the usual polyeste resin supplies, and all the accessories that someone may need.

Another thing about 50-50 mix hobby shop epoxies is that most of them are bonding epoxies and should not be used for laminating. They do ok with cabosil for thickening.