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Fiberglassing

Warning
Carbon fibre is extremely hazardous when it comes to sanding and will cause respiratory problems if a good dust mask is not used.
The dust will also settle on every thing in the surrounding area. Use an old vacuum cleaner (with an inline separator) and hold it against the area been sanded.

Carbon fibre dust is also conductive and can get into electrical equipment and short it out. Preferably use air tools and don't let the dust get into places you may later regret.

There is also the problem of handling the edges of tubes that have been made from carbon, the fibres can embed themselves in the skin causing blistering of the skin.

The same caution should be taken with all fibrous materials.
 

Fibre Glass

E Glass 163g - Used for everything, cheap and easy to use. Use 85g for a smoother finish.

Kevlar

Avoid it. It won't wet down easily and causes fury edges when sanded, cut or drilled.

Carbon

Most expensive of the three, brittle and most glues will peal off or separate.
Don't use it if transmitters are to be housed inside.

Combination mixes

You can get rolls of pre made mixes of different fibres.

My favourite combination for HPR is:
For making tubes:- Glass, carbon, then glass again.
For fins:- Glass, carbon, light ply in middle, carbon, glass.

Types of fibre
   
Epoxy
West Systems 2 part epoxy has fast or slow drying options.
Use the fast drying only in very cold conditions or on small jobs.
Use disposable plastic drink cups to mix the resin and some scrap paper to place the cup on during the process. If its hot weather mix half a cup at a time otherwise it will get hot and melt the cup before you have finished.

Left over epoxy will boil in the cup in hot weather, have a old tin can to dump it in or have a second use for any leftover epoxy. (Paper weights, fin fillets etc.) Don't rush the job by adding heaps of epoxy.

Massage each new layer of glass so that any excess epoxy from the previous layer soaks into the new layer.

The fiberglass ends will however get a bit messy and dry, so you will need to use a bit of extra epoxy here and work it in with your fingers.

Epoxy
   

Creating fiberglass tubes

Making fiberglass tubes is a bit of an art. Like cooking it needs preparation, time, and can get messy.

Mandrel preparation
1 First, find a PVC pipe longer than the size you need and of a suitable diameter for your design, this becomes your Mandrel. (Avoid Aluminium tubing unless absolutely necessary.)
2. Polish the mandrel and remove any high spots caused by scratches etc.
3. The mandrel needs to be turned during the fibre glassing operation so shove a dowel through the middle of your mandrel and support the ends with a table, saw bench etc. One end of dowel will have to be fixed otherwise the whole job will fall onto the floor when you least expect it.
4. Wrap the tube with "Glad Bake" paper.
The direction you wrap the mandrel is important as the glass has to be wound in the same direction.
5. Start from LH side of mandrel and hold the starting wrap with a strong elastic band ( tape wont stick unless wound around fully) and carefully do a spiral wrap keeping a even amount of overlap all the way along. When the end of mandrel is reached hold it with another elastic band.
6. Go back to start of wrap and recheck that the Glad Bake is tight on the mandrel with no exposed sections of mandrel (except at end of wrap) and no large creases.

A few notes before continuing instructions.

Glass wrapping:
Don't wrap the glass over ends of tube or over the rubber bands/tape.
Don't let the glass get dirty or touch the floor.
Put old news paper on the floor as you will get resin drops.
Test wrap the fiberglass first to see how long a length of glass you need. Or hang the roll from ceiling as a continuous feed and have an old pair of scissors handy to cut it.

Gloves:
Surgical gloves for small jobs. Rubber kitchen gloves for bigger jobs as epoxy will seep through thin gloves eventually.
Your gloved hands will get completely covered with epoxy so make sure everything is ready and nearby as you will not be able to reuse the gloves if they have to be removed. Things like scissors will get covered with epoxy so have some acrylic thinners nearby to drop them in.

Laying fiberglass

 

   
Wrapping the glass and applying the Epoxy
7. Mix the epoxy and run a bead of it along the mandrel.
8. Quickly drop the starting edge of glass on top. This part can be the most difficult on big jobs especially if the class is pre cut, so be carefully it doesn't drop onto the floor and pick up any dirt.
9. Make sure the glass is added in the same direction the Glade Bake was. If it goes on in the opposite direction the glade bake will bunch up underneath and you will need to start again.
10. Gradually add some epoxy on the dry parts of the Glass and work it in using fingers and palm, but don't twist the glass too much as it will get bubbles.

Removing the glass tube from mandrel
Warning: Use heavy garden gloves or similar when handling the tube otherwise you will get glass splinters.

11. Remove any tape or elastic bands. Remove any excess Glade Bake so that you can grip the mandrel.
12. If you used a aluminium tube or are making a very long tube, remove the tube just as the glass sets (stickiness has just disappeared but is still soft).
13. Tubes will (should) slide off mandrel easy if you slide it off from the side the Glad Bake wrap was started.
14. If the glass tube stops sliding don't force it, sometimes the Glade bake folds up underneath. try reversing the direction or spinning the tube on the mandrel as you reverse it.
15. The Glade Bake will come out easy after it has been removed from mandrel.

Its hard to give accurate guidance for making fiberglass tubes as methods have to be modified slightly for tube size, drying time and type & condition of mandrel.

Hints
* Try using "Shrink tape" straight after laying the glass then poke it with heaps of holes before hitting it with a heat gun. This will remove some excess epoxy.
* If you make the tubes late in the afternoon when day is still warm, remove the tube in the early morning when the tube is cold - it comes of easier.

 
   
Fins
Light but strong fins can be made by using "Light Ply" sandwiched between E glass.
For strong fins without using E glass - Try aircraft ply.

The fins in the picture has thin 3ply wood, 2 carbon, 2 Kevlar, 2 E glass layers each side just to see the result. - wont be using Kevlar again, got furry fin tips. But they wont break :-)

These were made for a rocket that takes "N" size motors.

Fin construction
 
 
 
 

 



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