stardust
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I am sure this has been covered before...some friends on this forum asked me to describe how I reinforce my rockets body tube and fins.
Here is how I glassed (glass reinforced plastic GRP) a scratch built "little bigger Bertha."
I used a round handle piece of a scraper clamped in a bench vice to hold the rocket. This way I can spin it around as I work on each fin. I used scrap pieces of glass cloth/resin between the fins on the body tube. Slightly overlap the pieces1/16th: to assure continuity of strength. This is one of the few project I am trying to see how strong and light I can make it. Kind of want to use the new 24 mm.Cesroni 3grain White on it. We'll see....
First I made fillets out of 15 min. epoxy mixed with 3M micro balloons to a thick paste. Globed it in with protected fingers. Swiped it into a cove with a rounded piece of tag board. Let it set up to a rubbery consistency and scratched the excess off with a pocket knife. The next day sanded the whole rocket with 120 grit sand paper. The micro balloons with epoxy sand easy so touch up of the fillets was not a problem. Once the whole project was sanded I washed the surfaces with denatured alcohol. Everything is clean... glass cloth, mixing container, brush mixing sticks, etc. I like the laminating Aeropoxy from Giant Leap Rocketry. It is strong and saturates wood, glass, prepped plastics very well. It also gives a long working time so I am not pressured to work fast. The resin/ glass can be bought bulk from a fiberglass supplier. I do not use enough to get a price break...so Leap has good prices and fresh/clean materials. Oh, store your glass cloth in a tight dry plastic bag. The atmosphere can have contaminates in it. Especially if one fries a lot of food in the storage area. I use natural bristle brushes. Epoxy fumes are tricky...don't smell too dangerous but they are not to good. I do it out side in the summer. In the winter I use a refrigerator box with a light bulb in it outside to cure things, and do the basic layup in the open garage. All the basic precautions. I wash up the brush, floor, cloths etc. with denatured alcohol from the lumber yard. Nitrile rubber exam gloves are the only ones worth using.
To start the laminating process paint a generous coat of resin over the surface to be glass reinforced. Then flop a precut clean piece of satin weave 3oz. glass cloth on to the work surface with resin. Using a resin loaded brush apply additional resin plastic to the glass on the work surface. A dabbing motion is best...brushing will move the glass around. The ideal laminate will not have so much resin on it that it hides the fibers of the glass. Use only enough resin to saturate the glass laminate. Dab away excess with the brush slightly dry from resin. Dab the brush into air bubbles trapped under the glass. This will work them out an allow the resin to move in. This will result in a stronger laminate and less sanding. Do not worry about excess resin along the edges it is easily sanded off later. Or while cured to a hard rubbery consistency it can be carefully trimmed with a knife or scissors. For additional layers of laminate lightly sand the cured existing layer and clean it with the alcohol or acetone. This will expose some of the glass fibers from the existing laminate. Some times a CSM (chopped strand mat) of varying weights might be used between woven layers to give thickness and a better bond between layers. I did not use any csm on this project. At this point sand it, prime it , and paint. Laminating is easy and fun!
Here is how I glassed (glass reinforced plastic GRP) a scratch built "little bigger Bertha."
I used a round handle piece of a scraper clamped in a bench vice to hold the rocket. This way I can spin it around as I work on each fin. I used scrap pieces of glass cloth/resin between the fins on the body tube. Slightly overlap the pieces1/16th: to assure continuity of strength. This is one of the few project I am trying to see how strong and light I can make it. Kind of want to use the new 24 mm.Cesroni 3grain White on it. We'll see....
First I made fillets out of 15 min. epoxy mixed with 3M micro balloons to a thick paste. Globed it in with protected fingers. Swiped it into a cove with a rounded piece of tag board. Let it set up to a rubbery consistency and scratched the excess off with a pocket knife. The next day sanded the whole rocket with 120 grit sand paper. The micro balloons with epoxy sand easy so touch up of the fillets was not a problem. Once the whole project was sanded I washed the surfaces with denatured alcohol. Everything is clean... glass cloth, mixing container, brush mixing sticks, etc. I like the laminating Aeropoxy from Giant Leap Rocketry. It is strong and saturates wood, glass, prepped plastics very well. It also gives a long working time so I am not pressured to work fast. The resin/ glass can be bought bulk from a fiberglass supplier. I do not use enough to get a price break...so Leap has good prices and fresh/clean materials. Oh, store your glass cloth in a tight dry plastic bag. The atmosphere can have contaminates in it. Especially if one fries a lot of food in the storage area. I use natural bristle brushes. Epoxy fumes are tricky...don't smell too dangerous but they are not to good. I do it out side in the summer. In the winter I use a refrigerator box with a light bulb in it outside to cure things, and do the basic layup in the open garage. All the basic precautions. I wash up the brush, floor, cloths etc. with denatured alcohol from the lumber yard. Nitrile rubber exam gloves are the only ones worth using.
To start the laminating process paint a generous coat of resin over the surface to be glass reinforced. Then flop a precut clean piece of satin weave 3oz. glass cloth on to the work surface with resin. Using a resin loaded brush apply additional resin plastic to the glass on the work surface. A dabbing motion is best...brushing will move the glass around. The ideal laminate will not have so much resin on it that it hides the fibers of the glass. Use only enough resin to saturate the glass laminate. Dab away excess with the brush slightly dry from resin. Dab the brush into air bubbles trapped under the glass. This will work them out an allow the resin to move in. This will result in a stronger laminate and less sanding. Do not worry about excess resin along the edges it is easily sanded off later. Or while cured to a hard rubbery consistency it can be carefully trimmed with a knife or scissors. For additional layers of laminate lightly sand the cured existing layer and clean it with the alcohol or acetone. This will expose some of the glass fibers from the existing laminate. Some times a CSM (chopped strand mat) of varying weights might be used between woven layers to give thickness and a better bond between layers. I did not use any csm on this project. At this point sand it, prime it , and paint. Laminating is easy and fun!
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