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Building Tips and technical articles. => Building techniques => Topic started by: Ty Marcucci on July 19, 2007, 08:46:27 AM
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I mixed equal parts a and b. Stirred and stirred until I go that sickly brown color. Applied it around the canopy, carefully masked off. Three days and it is still kinda soft. Now what?
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Hi Ty,
The "secret" is to heat each part (especially the brown part) separately before mixing, and then stir each part thoroughly, separately, each with its own stick. Then weigh the two parts and mix together at least 5 minutes. Then mix for another minute, etc! When you are convinced that everything is thoroughly blended, mix for yet another minute. Windy had an explanation for why this works about 5 years ago.
Oh, and if it hasn't cured within 24 hours, carefully scrape it all off. Use dope thinner to clean the area. And start over.
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I had the same problem. Won't touch the stuff now.
Bigiron
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Even if it does harden, sanding it is like sanding granite! Try using Super Fil from Aircraft Spruce or any Randolph dealer. Light weight and sands like medium wt balsa.
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That's the stuff I am currently using--- so far no problems. but a klutz like me will probably find some method to mess it up.
Bigiron
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I had a similar problem with some AeroPoxy Lite. I put the model in a car in the sun for two days . . . a sorta "Rube Goldberg" post-cure oven.
It worked. Sanded the filllets out with 80 grit, primed and sanded some more. The ship is now getting clear coats.
Good luck with yours.
Rick
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Ty- When you get the Super Fil, make a T shaped piece of scrap balsa and do a couple of test fillets to get a feel for this stuff. It doesn't seem to be very critical on the mix, it just changes the cure time. Working time is enought to give ample time to do your fillets. I just did the stabilizer and rudder on a T-Bird with one mix, one each mix later for each wing fillet. Follow the directions on the jar and you will do fine.
Don
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Hi Ty,
That fabulous blue stuff called "Super Fil" is the ONLY way to go! y1 ;D
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I don't get why so many people have trouble with Epoxolite. The stuff is almost idiot proof, which is why I use it. I never have any problems with curing and I'm not that carefull about getting exactly equal amounts of part A & B. I smooth it with a wet finger before it cures and almost never have to touch it with sandpaper. If I do need to sand it a little, it sands well. Yes, it's harder than balsa, but softer than granite. It has good strength when cured.
I wonder if it matters what climate you're in as to the performance of the stuff?
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Actually, I would prefer to make my fillets out of layers of wood, but wood is getting scarce around my workshop...............
I was using Sig Epoxilite sometime back in the early '70s. Tried Brodak's filler, too. Very similar to Epoxilite........
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I like the wood fillets also. I used them years ago on a couple planes. SF is the way to go over Epoxy Lt. for a couple reasons. It's less expensive and a no brainier to mix. I use a scrap piece of plywood 4"x5"x3/4" thick and use it to mix on with a tongue depressor stick, just wipe it off for quick clean up. rubbing alcohol to smooth out everything, even an hour later. I mask off the area that I am to apply my fillet first. get some paper towels ready with a small lid with alcohol. Then mix S?Pit it 2 parts blue to 1 part white. Your right you don't have to be perfect with the amounts. (another + over epoxy lite) Then I dab some all along the fillet area. Then spread it with my fingers, using 3 or four fingers, what ever works for the size your trying to shape, wiping your fingers and dipping them in the alcohol as you go. When I'm satisfied I take the tape off, then with a finger with alcohol a final wipe to smooth the tape line. You can do more then one fillet, but I like to do one side, top or bottom first then clean up everything and redo the mixing process over. I hope this makes sense and helps.
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I like the wood fillets also. I used them years ago on a couple planes. SF is the way to go over Epoxy Lt. for a couple reasons. It's less expensive and a no brainier to mix. I use a scrap piece of plywood 4"x5"x3/4" thick and use it to mix on with a tongue depressor stick, just wipe it off for quick clean up. rubbing alcohol to smooth out everything, even an hour later. I mask off the area that I am to apply my fillet first. get some paper towels ready with a small lid with alcohol. Then mix S?Pit it 2 parts blue to 1 part white. Your right you don't have to be perfect with the amounts. (another + over epoxy lite) Then I dab some all along the fillet area. Then spread it with my fingers, using 3 or four fingers, what ever works for the size your trying to shape, wiping your fingers and dipping them in the alcohol as you go. When I'm satisfied I take the tape off, then with a finger with alcohol a final wipe to smooth the tape line. You can do more then one fillet, but I like to do one side, top or bottom first then clean up everything and redo the mixing process over. I hope this makes sense and helps.
Hi Greg,
I agree totally! Epoxilite was great until I found Super Fil! It will have to be some really OUTSTANDING stuff to get me to change! (although I have been known to mix micro ballons in epoxy for some jobs)
The "one fillet at a time" is the way to go on the wings. I try to just mix enough to do each one then mix again until all four are done. It has all the "pluses" of Epoxilite, but it is easier to work and sand! (And believe me, I used enough Epoxilite to know! LOL!!)
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A "tool" for fillets: J.B Weld a few different size marbles and large ball bearings to pieces of dowel. These work nicely to "pull" down through the joint and give a very even radius. A *little* cap of alcohol or naptha to keep them clean and "slick".
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Hi Ty,
Haven't had a problem with mine breaking. I have thought about taking some large ball bearings to the school and the shop guy would weld them for me, but just never have......... ;D
Bill <><
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Well,
Since we were talking about fillet material, i'll put my 2 cents worth in here.
At Lowe's the other day I noticed a two part epoxy wood filler from "Elmers"
It cost $18.00, but looks to contain enough material to do at least 3-4 airplanes.
I'll probably try it on my ized Twister when I get to that stage with it.
Super Fil sounds pretty good to. I'll try it as well on probably the Akro.
Jim Pollock
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I went back to plain old epoxy/microballoons on my latest Avanti. That seemed to work at least as well as epoxolite.
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Jim,
Her is just one of the places you can get SF. And for that price you can do a dozen planes. Also here is some Super fil facts.
http://www.sacskyranch.com/cgi-bin/sh012344.pl?REFPAGE=http%3a%2f%2fwww%2esacskyranch%2ecom%2facatalog%2findex%2ehtm&WD=super%20fil&PN=Sacramento_Sky_Ranch_Primers_151%2ehtml%23a2388#a2388
USE:
An ultra lightweight corrosion-inhibiting filler for aircraft, marine, and automotive use. Adheres to composites, bare aluminum, steel, and bare or varnished wood.
Epoxy resin with non-MDA hardener. Ships non-hazardous. Apply EP-420 Epoxy Primer directly over SuperFil.
INSTRUCTIONS:
COMPOSITE FILLING: Use as you would an epoxy micro slurry. Mix by weight for best results. Scuff-sand smooth surfaces before application. Trowel or squeegee to desired thickness. After drying, sand to shape, and finish. Works as an excellent fillet material.
BARE ALUMINUM: Scuff surface with a Scotch-Brite pad. Treat bare aluminum with E-2300 Conversion Coating prior to application. Apply EP-420 Primer directly over dried SuperFil.
BARE STEEL: Clean off all rust and oil, and wipe with C-2200 Metl-Sol.
VARNISHED OR BARE WOOD: Scuff-sand and clean as necessary. EV-400 Epoxy Varnish may be applied directly over SuperFil.
MIXING:
By Weight (preferred)
2 parts A to 1 part B
By Volume:
2 parts A to 1 part B
Thoroughly stir each individual container of part A and part B before combining. Resin or hardener can separate from fillers during storage. After combining parts A and B, scrape the sides of the mixing container to insure a thorough blend. Mix to a consistent light blue color.
CURE:
Allow to cure at 70° or above for best results. Lower temperatures will lengthen the cure time.
Dry film cure: 8 hours at 77°
Cure to sand: 12 hours at 77°
POT LIFE:
One hour at 77°
CLEAN UP:
MEK before curing occurs
SHELF LIFE:
Two years unopened. Avoid storage above 100°. Resin will separate from filler during storage. Remix thoroughly.
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H^^ Ty, I went to West Marine and got some micro baloons and mixed them in some epoxy and that works well as a fillet material.. D>K
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More microballoons. The more you put in the easier to sand. This mixture also tends to form a nice round fillet when applied but I would still advise Super Fil.