I use the Bob Smith 15 or 30 minute epoxy with good results.  Still, I mostly use SuperFil unless I'm in a hurry and the fillets are small.

Which epoxy should we use for fillets.  I have "regular" 30 like you would use when building and Zap finishing type.  Does it matter?

Thanks,

James

IT DOES MATTER!  Don't use epoxy it does not sand well.  Use Fiberglass Resin with microballoons, it sands much easier than SuperFil. I have used both methods and they both come out real nice and are bullet proof, but I will now only use BONDO Fiberglass Resin, based on its ease of use. You can get it at Lowe's or any auto parts store.  It also cures faster than SuperFil and can be sanded in a few hours depending how much hardener you add.  It also works well for fixing dings on sharp edges and corners because you can control the consistency.  Give it a try you will not regret.  In photos blue is SuperFil and off-white is resin and micro balloons, the finished plane, which no longer exists (oops!), has the SuperFil fillets.  By the way I'll be in Springfield this August with a plane, perhaps we can get in a few flights with your son!

Don

This is the same stuff I suggested you guys use 8 years ago, and it's now becoming popular.

Are you surface finishing your models with Polyester Resin?

CB

I'm going to ask nicely that you not hijack this post and take it somewhere it was never intended.

James

James,
On my RC Pattern planes from many years ago, I used MB and 5 minutes epoxy. 

I use 30-minute epoxy, and they come out great. Mix as much micro-balloon dust into it as possible. That means past what you think it ought to take, but do it quickly. The working life is not really long. I use a Popsicle stick sanded to a radius I need to get the size fillet I want. It comes out pretty smooth, but needs some sanding. It takes a little time to sand, with your abrasive wrapped around an appropriate dowel, but if you've used enough micro-balloons, the final shaping is minor, and finishing is pretty easy. Added strength is valuable. Contrary to what some others have posted, I LIKE the process and results. I'm pretty hurried now, but if you search here by topic or my name, you'll find pictures of the process and results.

If your paint locker does not contain Superfill (like mine), good fillets can be made with 15 min. or 30 min. epoxy.  Use LOTS of micro balloons;  the more the better for ease of sanding.

Guys,I mix micro balloons with ZAP finishing epoxy with great results. The hardness or softness of the fillet is dependent on the ratio of balloons to finishing epoxy. Having 91% rubbing alcohol on hand makes smoothing out the fillet with a wet finger easy peasy. I've been using this technique for years. Cheers,PhillySkip