Buzzard Dave

Hi all. i'm about to start scratch building a 50cc aerobatic type. instead of buying phenolic tubes for the aluminum wing tube spar, i thought i'd just make some out of epoxy/fiberglass.

any tips?

can that be done by just waxing the aluminum tube and applying glass and resin? I'd think that would make it a bit too tight.

should i tape a layer of clear plastic (like plans protector, or monokote backing) over the tube, then wax that?

probably, i could get by with the lightest glass i have - right?


any info would be most appreciated - thanks.

David S. - Tampa, Fl

dreadnaut

My Feedback: (5)

Wrap the aluminum tube with 1 layer of 2 mil mylar; the stuff sold at Home Depot etc. as painters drop cloth. Tape it to the wing tube at the ends. Wrap 1 or 2 layers of 3 oz cloth/resin, and let it set until dry to the touch, but not completely cured. You want to pull it off before it shrinks too much. I've done this with 1" tubes, and they fit great.

PS. no need to wax. Epoxy resin will not stick to the mylar sheet.

Mike James

Here's a page with some vacuum bagging tips, including some glass wing tube sockets I made, that weighed 2 tenths of an ounce each. http://www.nextcraft.com/vacuum_bagging_01.html

Vacuum bagging isn't mandatory, but it does shave more weight off, and makes the parts less *****ly to handle.

giantflier

What is peel ply made from? What is it exactly?
Thanks

Ed Smith

I quote from the catalog of "Composites Canada" in Mississauga.

Peel Ply 52008
A 2oz smooth nylon fabric that has been scoured and heat set so that it is contaminent free and will not shrink during the curing process.

Peel Ply 52008 SBG
A smoothg nylon fabric same as 52008 but with a special release coating which makes removal easier.

There are other styles available.

Ed S

giantflier

What I usually do is:
1. Wax aluminum tube or spray it with silycon release.
2. Wrap it in 1-2 layers (not more) of polyethilen plastik film used in the kitchen. Make it even as possible. To make it absolutely even is not possibble. But it's all right, you just don't need it. Now alu tube is ready for making fiberglass tube.
3. Take a piece of waxed paper (from the kitchen again) a little bit bigger then fiberglass cloth piece.
4. Put fiberglass cloth on it and soak with epoxy.
5. Put another wax paper sheet from above. Roll it well in order to leave just enough epoxy.
6. Now you got some sort of sandwich (Paper-fiberglass-paper). Using knife cut exact size you need to wrap around the tub twice (not too much more!).
7. Peel away one layer of waxed paper and throu it away.
8. Wrap what left around aluminum tube gradually peeling wax paper away.
9. Now you have fiberglass cloth socked with epoxy wrapped around alu tube. It's almost done. Now wrap the same plastic film what you used for wrapping aluminum tube (kitchen stuff) above wet fiberglass.
10. Take masking tape and wrap it tightly around.
11. Let epoxy dray.
12. When epoxy is polymerized complitely take plastic from outside away. Then put the tube in oven and heat it around 100-120 C degrees for few minutes just to make wax melt.
13. Pull fiberglass tube from aluminum. When it's hot it'll go easily.
14. Pell plastic away from inside.
15. Your fiberglass tube is done.

Tips:
Wax paper used to keep fibefglass clth flat and straight. Second layer of wax paper helps to keep resin layer thin and even and make cutting easier.
Plastic wrapped on aluminum tube gives exact gap needed between aluminum tube and fiberglass one but without play.

martyg

My Feedback: (42)

What is the trick to keep creases out of the part when vacuum bagging?
When I pull vacuum, any slack in the layup seems to collect where the two halves of the bag join together.

funkworks

here is what i do for all mine... I use wax paper ( ive never tried mylar but maybe next time) and double sided clear tape. I use one layer of wax paper and i use fibergalss from a company called Aerosleeves. They make carbon, kevlar and fiberglass sleeves in different diameters. You slide it over your tube and then pull both ends to shrink it around your tube. I them mark the size i want the socket to be and then just wet out that area with a little overlap. Dont wet out all the cloth or you wont be able to get your tube out. You can buy the stuff by the foot and it works great. No more rolling up tubes, and a lot less messy. below is a pic of their carbon sleeve. You can by their stuff in different diameters and they say what is the min and max diameter each size will work with.

http://www.aerosleeves.com/

A. J. Clark

Seen a video where they just wraped the aluminum tube with wax paper
then wrap the glass cloth around that and soak it down with thin CA. Looked
like a quick way to do it. Probably need a fan on it as the fumes would be terrible.

TeamSeacats

I've had good success making fiberglass tubes around an aluminum mandrel with 2mil dropcloth as a barrier, fiberglass/eposy (I use fiberglass 1" woven tape and wrap in a couple of directions. Before I started vacuum bagging, I would tightly wrap the assembly with electrical tape and then pierce the electrical tape by rolling one of those framing nailplates (the ones with a ton of points) around the tape. The tiny holes allow excess epoxy to bleed out of the assembly and the tape keeps a good bit of compression on it. Once cured, the electrical tape removes cleanly and only leaves a few little picks from the holes and a very minor spiral edge from where the tape was wrapped. A quick pass with some sandpaper and it's ready for whatever it's going to be used for.

jnp

Thanks for the tip , have always made it the messy wrap around way with cloth . Have just checked with my supplier and we can get it in our part of the world . This is the way to go - simple and it will be neat !!

Brgrds
Juan

funkworks

yup... no more rolling up cloth for me. Ive make a few tubes from the stuff and its so much easier. One thing I did was hang the tube on one end and attach a small weight on the other as the resin cured to keep it tight against the tube. You will love how easy the stuff is to use. My first tube came out perfect.

jnp

Thanks will try it with the weight and let you know how it went . Unfortunately still a long way from the tube . Am still busy with the plug of the fuselage - doing some serious sanding at present getting rid of imperfections to get it 150% . Should get to the tube in approx Feb 08 .

Brgrds
Juan

1fireball

My Feedback: (1)

I just succesfully made a glass tube socket on my 2.125 carbon tube. I have a build thread on FG called 50% Extra 300 its in fourums git-r-done giant scale if you want to look.

Mike

Bass1

Looks like Areosleeves is shutting down operations! May have to try the CA glue trick.