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Building Tips and technical articles. => Building techniques => Topic started by: James Mills on May 20, 2018, 07:01:31 AM

Title: Microballon fillets
Post by: James Mills on May 20, 2018, 07:01:31 AM
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
Title: Re: Microballon fillets
Post by: jfv on May 20, 2018, 08:38:48 AM
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.
Title: Re: Microballon fillets
Post by: Brett Buck on May 21, 2018, 10:15:50 PM
Which epoxy should we use for fillets.  I have "regular" 30 like you would use when building and Zap finishing type.  Does it matter?

  SuperFil.

     Brett
Title: Re: Microballon fillets
Post by: Don Jenkins on May 23, 2018, 05:42:14 AM
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
Title: Re: Microballon fillets
Post by: Avaiojet on May 23, 2018, 07:17:36 AM
This is the same stuff I suggested you guys use 8 years ago, and it's now becoming popular.

The Fiberglass resin you refer to, is a 'polyester' laminating resin.

Actually available from Sig also.

See the Sig tech sheet at CFC Graphics vender's corner.

We finished our models with this stuff and I'll bet some of you are now doing the same.

I'e. Resin and glass cloth.

Don, you left something out.

This resin doesn't like being used over dope.

Are you surface finishing your models with Polyester Resin?

CB
Title: Re: Microballon fillets
Post by: James Mills on May 23, 2018, 08:00:52 AM
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
Title: Re: Microballon fillets
Post by: James Mills on May 23, 2018, 08:02:28 AM
  SuperFil.

     Brett
This is on a plane for Ben (profile Trophy Trainer) and we don't plan to paint the fillets, just trying to finish it out.

James
Title: Re: Microballon fillets
Post by: Crist Rigotti on May 23, 2018, 03:36:52 PM
James,
On my RC Pattern planes from many years ago, I used MB and 5 minutes epoxy. 
Title: Re: Microballon fillets
Post by: Dan McEntee on May 23, 2018, 06:29:05 PM
  It has been covered many times before, that this method originally started out with HobbyPoxy Smooth-N-Easy, which is a finish cure epoxy for laying up fiberglas, or was, as it is not available any more. I have been using Bob Smith Industries 20 minute finish cure product with great success. Smooths out easily with the finger in alcohol method and if done properly no need for sanding, but sands very easily if needed. You mix so much micro balloons in to get a putty type texture that it has to sand easy. Search out threads on the matter and my posts, I have spelled it out many, many times.
  Type at you later,
   Dan McEntee
Title: Re: Microballon fillets
Post by: Serge_Krauss on May 23, 2018, 08:17:24 PM
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.
Title: Re: Microballon fillets
Post by: James Mills on May 23, 2018, 08:25:12 PM
Dan and Serge,

Thanks for the tips.  I did a search to begin with but not with anyone's name included, that might have garnered more results.

James
Title: Re: Microballon fillets
Post by: FLOYD CARTER on May 24, 2018, 09:58:32 AM
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.
Title: Re: Microballon fillets
Post by: Avaiojet on May 24, 2018, 12:21:45 PM
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.

I agree, however, must be 'wet' enough to stick well.

I normally use 5 minute Epoxy using two cups. Epoxy/MB in one and hardener/MB in the other.

I use a tad of yellow paint so I don't over mix. Hardens quick.

CB
Title: Re: Microballon fillets
Post by: Skip Chernoff on May 24, 2018, 05:06:44 PM
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
Title: Re: Microballon fillets
Post by: Mike Griffin on May 24, 2018, 09:11:41 PM
I use both.. Super Fil and Micro balloons  mixed with epoxy.  I use West Systems slow cure epoxy.  I found both work well.

Mike