Author Topic: Fillets (Read 4241 times)

Pat · « **on:** January 22, 2013, 10:21:07 AM »

Hi guys,

I would like to hear peoples thoughts on wing fillets. What you use for them and how you do it.

Pat

Bill Little · « **Reply #1 on:** January 22, 2013, 10:33:01 AM »

Hi Pat,

I use Super Fil from Aircraft Spruce. I think I showed you the cans when you were over here. It is light, strong and sands very easily. Many of the top builders use this stuff.

I put it on after all the "covering" has been applied. I usually run my finger down the fillet to pre shape it.

BIG Bear
RNMM/AMM

Lauri Malila · « **Reply #2 on:** January 22, 2013, 12:57:50 PM »

Hi.

Sorry for slight off-topic but this is kind of related..:

Does anybody know for sure what the SIG Epoxolite mixing ratio BY WEIGHT is? I've lost the instructions.

Lauri

Randy Powell · « **Reply #3 on:** January 22, 2013, 06:08:12 PM »

I use SuperFil. I use a ball bearing (from an old mouse) attached to the end of a stick to put on the fillet and smooth it. dipped in acetone and works really well.

wwwarbird · « **Reply #4 on:** January 22, 2013, 06:43:51 PM »

Quote from: Randy Powell on January 22, 2013, 06:08:12 PM

I use SuperFil. I use a ball bearing (from an old mouse) attached to the end of a stick to put on the fillet and smooth it. dipped in acetone and works really well.

Well gawl-dang Randy, that ball thing is a great idea!!!

Trostle · « **Reply #5 on:** January 22, 2013, 11:50:46 PM »

Quote from: wwwarbird on January 22, 2013, 06:43:51 PM

Well gawl-dang Randy, that ball thing is a great idea!!!

Other options to help shape the fillets is to use whatever diameter tubing for your desired radius or use sockets from your tool chest for the desired radius. You can use thinner, or acetone, or alcohol to moisten the tool you use, then use a pallet knife to eliminate the excess material around the fillet edges.

Keith

Avaiojet · « **Reply #6 on:** January 23, 2013, 06:49:05 AM »

Quote from: Trostle on January 22, 2013, 11:50:46 PM

Other options to help shape the fillets is to use whatever diameter tubing for your desired radius or use sockets from your tool chest for the desired radius. You can use thinner, or acetone, or alcohol to moisten the tool you use, then use a pallet knife to eliminate the excess material around the fillet edges.Keith

Keith,

I do that, but it always seems I have to wrap sandpaper around something round or roll the sandpaper into a tube, then sand, to get it right.

I'm never happy with the first pass, and after that it's down hill. I make it worst with repeated passes, sometimes having to add material.

I have used tape on both sides, which has helped, but still requires a bit of sanding.

Charles

Mark Scarborough · « **Reply #7 on:** January 23, 2013, 01:00:15 PM »

Charles, part of your problem is that you use microballoons and epoxy ( or polyester resin, cant remember exactly,, not going to spend time to look,,)
SuperFill is the ticket,, and Unlike Randy and others, I use just my finger to shape it,, typically I have about 5 minutes of sanding on each fillet when its cured,, I use alchohol for a lube agent,, I also tape a guide line to protect the adjoining surfaces

Avaiojet · « **Reply #8 on:** January 23, 2013, 02:21:35 PM »

Quote from: Mark Scarborough on January 23, 2013, 01:00:15 PM

Charles, part of your problem is that you use microballoons and epoxy ( or polyester resin, cant remember exactly,, not going to spend time to look,,)
SuperFill is the ticket,, and Unlike Randy and others, I use just my finger to shape it,, typically I have about 5 minutes of sanding on each fillet when its cured,, I use alchohol for a lube agent,, I also tape a guide line to protect the adjoining surfaces

Mark,

OK!, OK!

I'll get some and try it.

MARK! I just went over there, stuff's 22.90!!!

Does it go a long way? Shelf life?

Ouch!

Charles

Serge_Krauss · « **Reply #9 on:** January 23, 2013, 11:27:05 PM »

'have to admit I really like the results of my 30-minute epoxy with microballoons. I mix in more microballoons than it appears the epoxy can possibly take and initially shape the fillet by passing a popsicle stick end, cut or sanded to my radius (or slightly larger), at an angle along the surface. I usually let it set after 30+ minutes with the jucture inverted and the wing and fuselage at 45^o angles to the horizontal. When the epoxy is mostly or fully set, I use a garnet paper wrapped dowel to re-establish a very accurate radius and remove surface "stuff". Result is quite smooth, but has good surface for adhesion. Otherwise, I'd wet sand with #400 emory paper around the dowl and Dupont Prep-Sol. That cuts FAST and very smooth, but I don't need/want it for this job. I just butyrate the surface 1/3 or 2/3 (both edges) at a time to ensure that there is minimal continuous shrinkage surface for first coats. 'never had one crack or anything lift over one, and I have "planted" them often enough to know at our grass field (see 2nd pic). I think this is a pretty strong and light enough option that certainly makes my wing/fuselage attachment overkill.

SK

Tim Wescott · « **Reply #10 on:** January 23, 2013, 11:58:31 PM »

I use epoxy+microballoons, like Serge. Mixing each half of the epoxy mixture with microballoons separately seems to help me get a nice mix-in, without worrying about using up my 30 minutes.

If you cram enough microballoons into the mix the result is plenty easy to sand, even if you let it fully cure.

I've made balsa fillets in the past. Never again, though, unless I'm finishing with something translucent or clear.

Claudio Chacon · « **Reply #11 on:** January 24, 2013, 06:00:24 AM »

Hi there,
I use balsa fillets on the wing and epoxi+microbaloons on other areas. The balsa fillets are done by cutting 4 or 5 "half ribs" (as for an I-Beam wing) of 1-16" sheet using the R-1 rib as a template and glue them together with Titebond or similiar glue for easy sanding. Next step is a rough sanding with a rounded tip coarse drum sander with a Dremel tool.
Last, I glue some #220 grit sand paper to a wood dowel to get the desired radius and shape.

john e. holliday · « **Reply #12 on:** January 24, 2013, 12:33:53 PM »

This reminds of the article someone wrote quite a few years ago about using light balsa sheet the thickness he wanted the fillets. After makeing a template he would cut peices to around the wing next to the fuselage. Then tape at the edges so he could sand the fillet down to where it looked good. He made it look easy.

Paul Wood · « **Reply #13 on:** January 24, 2013, 02:07:12 PM »

Quote from: Pat on January 22, 2013, 10:21:07 AM

Hi guys,

I would like to hear peoples thoughts on wing fillets. What you use for them and how you do it.

Pat

Pat,

I agree with the techniques listed in the above posts. I've used most of them over the years and they all work well. But, here's the method I've used for the past several planes. (I know you guys are tired of seeing this Nobler, but it serves to show my method regarding fillets). I use the Elmers wood putty shown in the attached photo. Use the red label (interior), not the green (exterior). The exterior brand is very gritty and harder to sand. I apply using my finger dipped in water. Contour and smooth with finger tip. Let dry and sand using your favorite method. You can then smooth a very thin layer on to fill any low spots. After final sanding, I apply a very, very thin coat of epoxy rubbed in with my fingers. Blend into the surrounding surfaces. This protects the putty and, after light sanding, allows the primer to stick better. I also use this around canopies and rudder/fuselage junctions. The attached photos show the results. Not perfect, but good enough for me.

Glenn (Gravitywell) Reach · « **Reply #14 on:** January 24, 2013, 02:17:08 PM »

What about a fillet like a Spitfires, that starts small at the front and becomes bigger as it goes to the back. The I-16 Ratta is a good example of what I mean. Would Superfill do this?

Paul Wood · « **Reply #15 on:** January 24, 2013, 04:24:54 PM »

Quote from: Glenn (Gravitywell) Reach on January 24, 2013, 02:17:08 PM

What about a fillet like a Spitfires, that starts small at the front and becomes bigger as it goes to the back. The I-16 Ratta is a good example of what I mean. Would Superfill do this?

Glenn,

I have done large fillets using blue foam as the filler. I rough shape the foam using various files and sandpaper, then use the Elmers putty as described above. If it's a rather large fillet like the Spitfire, I use shaped 1/16 balsa "ribs" spaced between foam pieces to ensure identical left and right fillets. I have used spackling in the past, but it is much more fragile to work with than the Elmers. Large fillets definitely need the epoxy surfacing to prevent cracking when flexed in flight.

Avaiojet · « **Reply #16 on:** January 24, 2013, 06:23:17 PM »

Sometimes farings/fillers are made uneven to duplicate the look fo the actual aircraft.

Typical with scale models, if the farings are uneven.

Charles

Glenn (Gravitywell) Reach · « **Reply #17 on:** January 24, 2013, 06:33:56 PM »

I se what you mean Charles. You're actually duplicating the uneven look of the metal surfaces. Thats cool.

Paul, the blue foam idea is good, excellent even. It definitely goes with my cheapskate side cause I get free chunks of it from job sites! LOL

Tim Wescott · « **Reply #18 on:** January 25, 2013, 06:01:10 PM »

Quote from: Tim Wescott on January 23, 2013, 11:58:31 PM

I use epoxy+microballoons, like Serge. Mixing each half of the epoxy mixture with microballoons separately seems to help me get a nice mix-in, without worrying about using up my 30 minutes.

If you cram enough microballoons into the mix the result is plenty easy to sand, even if you let it fully cure.

I've made balsa fillets in the past. Never again, though, unless I'm finishing with something translucent or clear.

I just put some fillets on a plane. Spurred on by god only knows what evil genius (well, and the fact that it's long and straight so it should be easy, right?) I made the first one wood. Dumb, dumb, dumb. Took me way longer than the epoxy and microballoons that I used on the other side took, and it looked worse, too.

Avaiojet · « **Reply #19 on:** January 28, 2013, 11:10:28 AM »

Here's a fillet that's made to look like an aircraft faring.

Could feather or blend it in with a filling material, or add simulated screws as would have the real aircraft.

Did this at 3:00 AM this morning, so it's not totally perfect.

Gr. Good will fix it.

Model, The LOSER.

Derek Barry · « **Reply #20 on:** January 28, 2013, 01:17:11 PM »

I used micro balloons and epoxy for many years. Frank McMillan introduced me to SuperFill (the blue stuff) I like it better than the Micro Balloons with epoxy. Either one works well.

Derek

Avaiojet · « **Reply #21 on:** January 28, 2013, 02:07:43 PM »

Derek,

Isn't that blue stuff, (SuperFill) "water based?"

Charles

Derek Barry · « **Reply #22 on:** January 28, 2013, 02:49:04 PM »

Quote from: Avaiojet on January 28, 2013, 02:07:43 PM

Derek,

Isn't that blue stuff, (SuperFill) "water based?"

Charles

No it is a two part....something. The white filler that I see on your plane is water based, but I use that too.

Randy Powell · « **Reply #23 on:** January 28, 2013, 04:17:01 PM »

SuperFil is an epoxy based material. 2 to 1 mix. Extremely light and very sandable. Cool stuff. Other stuff works, too. It just seems to do the best for me.

I also use a catalyzed glazing compound for filling small scratches and such; minor imprefections. I use Dolphin Glaze but others use Evercoat pretty successfully. The thing that makes this nice is that it doesn't shrink and just about anything will stick to it, unlike regular glazing compounds.

On the other hand, what do I know.

Howard Rush · « **Reply #24 on:** January 28, 2013, 09:50:57 PM »

I don't like SuperFil. Mine has the consistency of day-old oatmeal. It took me several applications to get a decent fillet. I asked Aircraft Spruce if it was old stock, but they said they hadn't had any complaints. I used some yesterday on a cabinet I'm building for the house. It didn't work there, either.

Tim Wescott · « **Reply #25 on:** January 28, 2013, 10:37:01 PM »

Quote from: Howard Rush on January 28, 2013, 09:50:57 PM

I don't like SuperFil. Mine has the consistency of day-old oatmeal. It took me several applications to get a decent fillet. I asked Aircraft Spruce if it was old stock, but they said they hadn't had any complaints. I used some yesterday on a cabinet I'm building for the house. It didn't work there, either.

What's the temperature in your shop? If you've only ever used the stuff in the cold it could be that.

Derek Barry · « **Reply #26 on:** January 29, 2013, 04:11:08 AM »

Quote from: Howard Rush on January 28, 2013, 09:50:57 PM

I don't like SuperFil. Mine has the consistency of day-old oatmeal. It took me several applications to get a decent fillet. I asked Aircraft Spruce if it was old stock, but they said they hadn't had any complaints. I used some yesterday on a cabinet I'm building for the house. It didn't work there, either.

Did you stir part A and part B separately before you mixed them together? The stuff seems to separate in the jar when left on the shelf for a long time.

Derek

Howard Rush · « **Reply #27 on:** January 29, 2013, 09:26:46 PM »

Quote from: Derek Barry on January 29, 2013, 04:11:08 AM

Did you stir part A and part B separately before you mixed them together?

Yes. Reckon I should have used separate sticks?

John Leidle · « **Reply #28 on:** January 29, 2013, 09:28:41 PM »

I use balsa as fillets, sand to shape, then finish the edges with filler or putty of choice.
john

Author Topic: Fillets (Read 4241 times)

John Leidle