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Glassing help?

Old 04-03-2009, 04:28 PM
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CBM Racing
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Default Glassing help?

Hey all. Weather has been sporadic at best lately, so building a new sailplane till it calms down some . I built up the fuse with foam and hotwired/sanded to the shape I wanted (mostly). It is 72 inches long, 5 inches high at wing saddle area, 3 inches thick at thickest point. All hollowed with a weight of of about 12ozs so far with battery installed. It was going to be just a throw together plane for fun and thrashing, but came out much better than expected. I started glassing the nose from wing saddle forward, and hope it isn't ruined[:@]. I haved glassed small projects and many flat/simple curves like wings, but never the compound tapered curve I have here. Am I better off trying to do it in small sections like first bottom, then sides, then top? Or trying to do larger areas at once like wrapping about a foot at a time all the way around? Any help would be great. Not bagging it, just covering and then wrapping with sarran wrap to keep it tightly in place and smooth. Guess maybe I should do one section at a time, bootom, then one side at a time, then top. Arg, wish I had more experience with epoxy glassing!
Old 04-03-2009, 05:55 PM
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soarrich
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Default RE: Glassing help?

3 Oz. Fabric: 50" Wide Satin Weave @ http://www.acp-composites.com/home.php?cat=261 will work.

I'd do a layer to behind the TE, then a layer full length of the fuse. Spray the foam with a light misting of 3M 77, lay the first layer down, the respray the glassed part and lay a layer full length. After you've got the glass a spread out with out wrinkles and the overlaps trimmed nicely lay on you epoxy, west 105/205 will work well. Brush it on until the class is wetted out, it disappears, any spots that are still white need more epoxy. I'd work with the seams on the top of the fuse, that way you can do the complete bottom working your way down the sides, then you'll only need to do the top of the nose and behind the wing.

I built a Merlin fuse like this 20 years ago, and I am going to do a XC ship like this soon.
Old 04-03-2009, 07:55 PM
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Default RE: Glassing help?

Thanks for the info, but stuck using what I have this time around. Using Z-Poxy finishing resin with glass cloth from automotive dept. Was going to top that off with another layer of 1/2oz cloth for easier filling and final finish, unless using one layer is the better way to do it? Unwrapped the nose portion and it wasn't as bad I feared, but not as nice as I had hoped . At least it's usable! I have the 3m77 spray and will try that to "tack" the cloth in place. Now I have a bit of sanding to do to nock off some excess resin spots. Thanks again!
Old 04-03-2009, 09:58 PM
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Default RE: Glassing help?

It's much easier if you have all the little re-enforcing doubler pieces under the finish layer. I wouldn't put the plastic over it , just put the glass on then just enough resin to wet it out. You can then make a flow coat with some micro balloons in it, ( or get one of the WEST fillers), the micro balloons make it easy to sand. You may also try drawing a single edge razor backwards over the surface, it will shock you how that take excess resin off.
Old 04-04-2009, 03:33 PM
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Default RE: Glassing help?

Ok, things are shaping up fairly well now. Sanded high spots and excess resin of nose, a real hassle it was so thick, lesson learned! Sanded whole nose piece with 180 grit and wiped with tack cloth and then denatured alcy. Some areas were really thin after sanding, so today followed advice and put another layer on after tacking in place with 3m spray and then cutting most excess off leaving about 1 inch overhang. This layer is on the bottom from nose to trailing edge of wing saddle wrapping to just over top deck. Started to squeegie of resin with plastic bondo scraper, then blotted with tp and NO WRAP. amazed at difference these little step made, so much cleaner and smoother . Tomorrow will do rest of bottom and sides and next week top and vertical fin. I will post some pics showing bottom after it is done, and some finished ones. It wont be a contest winner, but it is quite fetching in my opinion. Thanks for helping, anymore tips would be welcome as well. Thanks again!
Old 04-05-2009, 04:54 PM
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Default RE: Glassing help?

ARRRGH! Here's a tip, don't use the bondo brand glass cloth from hardware stores [:@]. That is what I thought I had used, so when I was running short went and got more. It might be fine for flat or very light curves, but is so thick that it tries to lift edges and return to a flat sheet. It also lifts from structure trapping air bubbles under it. Man, I am so dissapointed right now, not even funny. At least the fuse is still ok, just have a buttload more sanding made for myself. Also, 3m77 WILL eat pink foam. I tested a scrap piece as usual and laid it on just a little thick, 10 minutes later I looked and it ate a big area out of it. So if you do use it, use very very lightly. Any ideas on how to remove trapped air after it is 7/8 set up? After looking again I know what happened. It bubbled right over a glue joint in the foam, so either it gassed off due to temp change, or some reaction between resin and gorilla glue for joints. Pics to come soon!
Old 04-09-2009, 05:53 PM
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Default RE: Glassing help?

Yup, the bondo glass is really heavy stuff, kinda overkill, it's about 6 oz, in the future, just go to west marine or any marine supply house and ask for light weight glass cloth, say around 2-3 oz , then use the 1/2 or 3/4 oz glass cloth for final, I almost never use 3M super 77, I just use the resin to hold it down, and on sailplanes and smaller planes up to 3 lbs, just doing 2 or 3 layers of 3/4 ozs glass is plenty for streingth and durability. The structure get's it striength from the wood, the epoxy-glass finish will soak into the sheeting and tie it all together and give the plane a smooth stiff surface. I did a small quickie 1/2A plane in epoxy glass finish and it only added about 2 ozs to the planes weight, paint added another 1/2 to 3/4 oz. One day the wing got knocked off the bench and hit the stool I sit on before hitting the ground, not even a scratch of dent in it, and that has only 1 layer of 3/4oz cloth on it. very light and stiff. The dope surface is polishable with 3m finess-it to a mirror shine.
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Old 04-15-2009, 08:25 PM
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Default RE: Glassing help?

Ok, life got in the way there for a while, but back at it again. Funny how these "small simple" projects take on a life of there own sometimes. First off, thanks to you guys for tips and help, really appreciated. Second, pics comming soon, really! I wanted to post some pics earlier, but was to embarrassed by my lack of skills to show it . Now I am over that hurdle though. I figure, I made it with my own hands, I like the lines, and it has kinda turned into a labor of love for me. So I guess a "few" imperfections shouldn't damper my enthusiasm! Going to put one layer of .56 oz. cloth on vertical fin tonight, sand SOME MORE in the morning, and put on first coat of primer and take a pic or two. Then it is MORE SANDING, then another prime coat, then see if it's ready for painting yet. Thanks again for all tips, knowledge, and help. Learning a bunch from this simple project!
Old 04-16-2009, 08:16 PM
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Default RE: Glassing help?

Argh. Now my camera is on the fritz! Cripes, one thing after another this week! But, got 1 primer coat on today, man does that make the oopsies pop out at ya. It's not to bad, a few pinholes and some low spots to fill. Question is, do I sand the prime coat first, or fill pinholes and low spots then sand? Thanks for any advice.
Old 04-16-2009, 08:22 PM
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Default RE: Glassing help?

get a tube of glazing putty for the pinholes and if the low spots are thin you can use it there also,better to sand what you can but glazing putty will stick to anything and easy to sand
Old 04-16-2009, 09:31 PM
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Default RE: Glassing help?

Awesome, thanks!

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