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Fiberglass technique

Draker

Well Known Member
I've decided to dive right into learning how to work with fiberglass by working on my -7's canopy fairing. Really confused at this point. I've been mostly following the RV-14 canopy fairing help video that Vans publishes, but working with the cut fiberglass is not going as nicely as it goes in the video.

My problem seems to be when pre-saturating the cloth with epoxy on the workbench, the cloth gets distorted and frayed every time I so much as touch it. And if I do manage to get the epoxy on it nicely, as soon as I peel it off my work surface, it gets wildly stretched and frayed. Nothing like the nice straight edge that the skilled craftsman in Vans' video ends up with. Every piece I work on looks like this after I peel it from the work surface:


(The above was more of a square piece when I cut it)

Any good techniques for making this stuff keep its shape and nice straight edge before applying to the airplane?
 
Easy

Take one of the heavy black plastic trash bags and cut into appropriate sized pieces for the piece you are working with. Say, an inch or two all the way around the piece of glass or carbon.

Wet out the material on the plastic then move the material and the plastic to the canopy. The plastic keeps the material under control.Lay it in position and press it down. When satisfied, peel the plastic off. Keep one hand free to continue to press the material down.

Now add peel ply and wait for it to cure. It is satisfying to peel off the peel ply and see the results.
 
Technique

There are many techniques, below is my favorite:

1) clear plastic sheeting on work table
2) lay cloth on plastic
3) pour resin on cloth
4) place another clear plastic sheet on cloth
5) move resin around with a spreader or roller on top of plastic
6) draw shape on plastic
7) cut the plastic and cloth sandwich with scissors or a rolling fabric cutter
8) peel off bottom plastic sheet
9) place cloth and top plastic sheet in position on airplane
10) use your spreader to attach and hold cloth in place while you remove the top plastic sheet


EDIT: Darwin appears to type faster:)
 
Are you using whole bolts of fabric and cutting to desired size? You may have invested as much as you want in fabric so this thought might be too late. I bought and used several sizes of tape for doing the canopy, which has selvage that didn't unravel or change shape. This cost more but I was determined to avoid the situation you are now facing. If you want to spend the money on tape it sure saved me a lot of headaches as a first time fiberglasser.
 
Thanks! Lots of good suggestion to try! Seems like the key to all of them is to not handle the fiberglass strip by itself without something to assist it keeping its shape. Will try these.
 
Fiberglass tips

I wrote one up too. Look under the pages links on my blog.
Basically...
4mil plastic. Any hardware store.
Cut a piece about 2" bigger all dimensions.
Lay the fabric on top.
Use my Epoxy Calculator to estimate the amount needed. Credit to Dave for the formula.
Spread with a credit card till saturated. Should be translucent.
Move the whole thing to the part.
Smoosh it in place.
Peel off the plastic.
Cut sections of peel ply and apply them
Use the leftover epoxy to saturate and smoosh out air bubbles.
Peel off in the morning.
Lather, rinse, repeat.
No problem.
If you really want sharp edges, cut it with a rotary fabric cutter after it's saturated.
 
How many plies can you apply on top of one another before waiting for it to cure, sanding, and continuing to lay on plies?
 
Look up the old Mike Arnold AR5 airplane videos on YouTube. .there goes hours and hours. ..he's got a lot of good info, some say outdated, but it's a place to watch an artist at work!
 
Plies

How many plies can you apply on top of one another before waiting for it to cure, sanding, and continuing to lay on plies?

You can stack as many as you like. I prefer to either wet them all at once or wait till they cure with peel ply, rip it off and add plies. Never tried adding plies to a partially cured layup but it should work. Just make sure there's no bubbles between.
 
Thanks! Lots of good suggestion to try! Seems like the key to all of them is to not handle the fiberglass strip by itself without something to assist it keeping its shape. Will try these.

Exactly, do not handle.

I do a lot of this making parts . . .I weigh the glass, then weigh out the resin to 1.2X to start. Little flexible spreaders are made from milk cartons. Make a few dozen and keep handy. Pour on the resin in a streak then spread very gently to near edges. Depending on the size, Saran wrap or Reynolds kitchen wrap, the really thin stuff works well. Otherwise 4-6 mil polyethylene works well too. Stretch out the wrap, tape the corners, lay all the pieces of reinforcement, pour on the resin, spread to edges, wait for soaking, wet more as needed. You can add a top layer then use a spreader on top, or a roller. Of just wait and only use a bottom layer. I typically do this, but not always.

Potential issues are pressing with fingers will make dry spots, and so will too much rolling. To keep from the edges from picking up too much glass, I cut the wrap pieces with a razor close to the glass, peel off the top (if you used it) then take the glass, lay down and peel off the wrap before adding the next layer. A wet glass strip is so much easier to handle and get applied precisely with the wrap still on the back.

A top layer of wrap will pull threads, when only using a bottom it will be a little excess resin, but I find every third layer can be dry glass - just lay it down and it will soak up the resin rich layers below - yes a little gentle, slow rolling with a grooved roller is needed. Stippling works too.

So, a little of this little of that, adapt to the process as it proceeds and all done!!

For doing a canopy, a friend really helps, staging the mixers, varying the weight as needed as you go and doing the wet layout. Work as a team.

We have had best results by knowing what kind of fillet radius we wanted every 6" around the canopy, had cardboard templates made and as the canopy layup proceeded, vary the strip sizes (already cut in preparation) and lengths to fill in the progressive radius to near net shape. Do this the filling as you proceed so the last layer or two is continuous.
 
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Confession

Confession time: After taking a few months of learning and practice, I really love working with fiberglass! It's the opposite of metal.. The material itself is forgiving and doesn't have to be treated with kid gloves. Mistakes don't cost anything. The more you work on it, the better it looks (as opposed to metal). Working with the material makes me feel like a sculptor instead of a mere technician. This may be heresy here, but I think my next airplane build may be Glasair :p

Here's my first creation. Might look ugly to you pros but the project was fun, I learned a lot, and I believe it is airworthy. Instead of riveting those hanging metal doodads to the horizontal air snorkel, I molded a flange for it that mates right up to the angled left air ramp behind the cowl opening. It was laid up in-place on the airplane, so it fits both the air filter and the ramp exactly and is airtight without proseal. It also has a small flange in front rather than leaving that area of the filter unsupported as the plans propose. This still has a little more sanding and smoothing to go, then a light coat of primer.



The fit:



 
Welcome to the Frankensnorkel club!

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Nice job Ryan... Maybe you would like to come to our hanger and help with our glass ??? We hung the engine today and we are feeling pretty good about ourselves.

Bob
 
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