katipo

My Feedback: (3)

Hi all
I would like to make some composite panels with balsa as the core. Does anyone know of a site or other source that has info and tips? I have made a few with some luck but the last one I did the 2 oz glass and carbon tissue composite let go of the balsa on one side. I had a real job getting the peel ply to come off on that side since the breather cloth socked up the epoxy and together they got very hard. I think that the extra force I needed to use delaminated the composite from the soft balsa. And if you are wondering yes I did use just normal balsa sheet as you just can't get model sized end grain balsa around here.

Cheers
Katipo

probligo

Delamination like that is just as likely to be the result of either poor adhesion as a result of a dusty surface, or overflexing.

I am building solid F1A flying wings using 0.5 glass as part of the reinforcing system. They are NOT designed for zoom launch or circle tow. I have not used vacbag, but I have washed the surfaces with dope thinners and a lint free rag before applying the epoxy and glass.

I have tried ffhlg wings with glass reinforcing but there are few to no advantages and plenty of disadvantages.

So far, touch wood (he says patting his head ), I have not had a delam.

Atlanta 60

My Feedback: (18)

Hey....do you use a PFE layer between your peel ply and your breather???...if not...I can imagine you having a tough time!!!...it is a real mess when the breather becomes saturated and sticks to your part...I would not expect your laminate to hold up trying to get it apart...I have a thread called "vacuum bagging" maybe take a quick look at it and see if it will help you...good luck!!!!

http://www.rcuniverse.com/showthread...21&forumid=206]

katipo

My Feedback: (3)

Thanks guys.
I know I have lots to learn but that's half the fun of this hobby.

I made up two more panels last night but this time I tried something that I had been thinking about for a few days now. As I explained in my first post thin end grain balsa is hard to come by and very expensive compared to normal sheet.
:idea: So what would happen if you would puncture the normal sheet balsa with thousands of tiny holes? Would this not allow the resin to get a better bond or key to the balsa as it does with the end grain?
I thought about the extra weight however it ends up hardly any more and a lot less than the end grain balsa, which acts like a sponge.
To make the tiny holes I used an old wire brush and rocked it backwards and forwards across both sides of the sheet.
Well the panels have come out light and strong. But I still need to do some test etc.
Has anyone heard of this method or done something similar before?

Cheers
Katipo

TT2

My Feedback: (13)

The primary reason to use end-grain balsa in a composite 'sandwich' is because of it's compressive strength since the grain is oriented perpendicular to the outer layers. Much stronger than using 'regular' balsa.

Because of the epoxy starvation problems when using end-grain balsa or other porous core materials (rohacell, divinycell, etc.) I cure my outer layers (skins) separately before laminating to the core material. The results are worth the added effort...which really isn't much.

-Tom

Darrinc

My Feedback: (5)

TT2 is right on with the proper way to make your A-Sandwich laminate.

Regards,

e-bird

navav2002 what are you talking PFE layer. I use the pouris peel
ply with two layers blue paper shop towels. Haven't heard of PFE
on compound curved surfaces I use plastic sandwitch material
with pin hole I do get some bleed that way. Renyolds say the new
no stick alu foil haven't tryed it yet. CU