carbon fiber repair/ epoxy question



Status
Not open for further replies.
C

Chris Crawford

Guest
Hi All - I have a CF hardshell bucket seat for a recumbent bicycle. On the back of the seat are 2 2"
ribs running up and down for support. One of these ribs hit something sharp which left a spidery,
crooked, 2" long crack across it (horizontal).

I'd like to repair this and am looking for advice from an expert. I'm currently considering using 2"
or 3" CF "tape" and SystemThree T-88 epoxy and layering it up with 3 layers, one slightly larger
than the other. Does this sound like it will work?

Also while we're on the topic: I'm interested in epoxy bonding some .75" OD x .049 wall Al tubing
that has been mitered together for a light load bearing application. Should I be using a filler with
the epoxy and if so, what kind?

Thanks in advance, Chris
 
I have some limited experience with fibre glass and epoxy which I use when building strip kayaks.
The solution for the seat sounds like it should work. The CF tape sounds like over kill. You could
probably do it cheaper with 2 layers of glass tape. I would suggest that if you have not worked with
epoxy before you practice a bit before you work on the seat. It not difficult it just hslps to know
how the stuff behaves so you can plan your work. As for bonding the tubing the only thing I can say
on that is try and see. Fillers night help a bit if you use the fibre type rather then something
that is just going to add bulk. This is a place the CF tape might help if you plan on doing
something other then just glueing them together.

Lot of good info here. http://www.oneoceankayaks.com/
http://www.blueheronkayaks.com/kayak/index.html Check out cradles

Chris

"Chris Crawford" <[email protected]> wrote in message
news:[email protected]...
> Hi All - I have a CF hardshell bucket seat for a recumbent bicycle. On the back of the seat are 2
> 2" ribs running up and down for support. One of these ribs hit something sharp which left a
> spidery, crooked, 2" long crack across it (horizontal).
>
> I'd like to repair this and am looking for advice from an expert. I'm currently considering using
> 2" or 3" CF "tape" and SystemThree T-88 epoxy and layering it up with 3 layers, one slightly
> larger than the other. Does this sound like it will work?
>
> Also while we're on the topic: I'm interested in epoxy bonding some .75" OD x .049 wall Al tubing
> that has been mitered together for a light load bearing application. Should I be using a filler
> with the epoxy and if so, what kind?
>
> Thanks in advance, Chris
 
Chris Crawford <[email protected]> wrote in message
news:<[email protected]>...
> Hi All - I have a CF hardshell bucket seat for a recumbent bicycle. On the back of the seat are 2
> 2" ribs running up and down for support. One of these ribs hit something sharp which left a
> spidery, crooked, 2" long crack across it (horizontal).
>
> I'd like to repair this and am looking for advice from an expert. I'm currently considering using
> 2" or 3" CF "tape" and SystemThree T-88 epoxy and layering it up with 3 layers, one slightly
> larger than the other. Does this sound like it will work?
>
> Also while we're on the topic: I'm interested in epoxy bonding some .75" OD x .049 wall Al tubing
> that has been mitered together for a light load bearing application. Should I be using a filler
> with the epoxy and if so, what kind?
>
> Thanks in advance, C

Sounds ok (the seat). I have worked with some West System epoxy (essentially the same) and you could
go with a random weave glass if you have not already purchased the carbon tape (cheaper, etc...).
Those epoxies are UV sensitive - you may want to locate some UV blocker (I forget what they call
it). Don't forget to rough up the surface (80 grit is good) and wipe with acetone. You might grind
out the area to the width/depth of the patch as well for a cleaner repair. Either purchase a cheap
roller (a small metal implement that looks like a tiny paint roller) or use a disposable brush to
move (with short vertical stabbing motions) the air bubbles out of the weave.

As far as attaching the tubing goes, you would want to create a fillet with epoxy and fumed silica
or microspheres prior to the application of the mat or weave. The fabric doesn't like to do sharp
bends and you will end up with lots o voids otherwise. No filler needed after you make the fillet.
Should be plenty strong for a light load.

App
 
check out http://www.damonrinard.com/carbon_fiber.htm

damon describes his materials and methods in this very interesting piece.

Chris Crawford wrote:
> Hi All - I have a CF hardshell bucket seat for a recumbent bicycle. On the back of the seat are 2
> 2" ribs running up and down for support. One of these ribs hit something sharp which left a
> spidery, crooked, 2" long crack across it (horizontal).
>
> I'd like to repair this and am looking for advice from an expert. I'm currently considering using
> 2" or 3" CF "tape" and SystemThree T-88 epoxy and layering it up with 3 layers, one slightly
> larger than the other. Does this sound like it will work?
>
> Also while we're on the topic: I'm interested in epoxy bonding some .75" OD x .049 wall Al tubing
> that has been mitered together for a light load bearing application. Should I be using a filler
> with the epoxy and if so, what kind?
>
> Thanks in advance, Chris
 
Status
Not open for further replies.