Composites Central


Reply
Old 05-31-2015, 04:27 PM   #1
Creator

Member
 
Join Date: Dec 2013
Location: Limassol cyprus
Posts: 141
Thanks: 10
Thanked 5 Times in 5 Posts



Default Carbon Fiber repair

I repaired a bike frame made of carbon fiber (Specialized fact r11 type) It has 2 cracks the one next to the other. The method i decided to use is wrap Cf around the crack 0 +45 and - 45 degrees -330gr/m2 unidirectional prepreg. Everything seems to go smoothly but i have one question . The procedure i used was this :
I sanded the primer paint coat and exposed the existing carbon fiber in the whole area i was ging to wrap new cf
Then i used some repair paste to close the crack , then i sanded again the repair and last I wrapped Cf around the area i sanded ...then vacuum and inside the oven.
I DID NOT USE PRIMER or any bonding agent to bond the old with the carbon fiber.
1) Should i worry for delamination ?

2) I want to repaint the whole frame. Can i use the type of paints used for motorbikes or i have to use special primers / paints for carbon fiber?
Creator is offline   Reply With Quote
Old 05-31-2015, 09:50 PM   #2
Hanaldo

Composites Expert
 
Join Date: Feb 2014
Location: Australia, WA
Posts: 745
Thanks: 1
Thanked 157 Times in 138 Posts



Default

Automotive paints will be fine.


What grit sandpaper did you use? You don't need a primer to bond to carbon, so long as the surface is clean and mechanically keyed you will get a very strong bond.
Hanaldo is offline   Reply With Quote
Old 05-31-2015, 11:08 PM   #3
Creator

Member
 
Join Date: Dec 2013
Location: Limassol cyprus
Posts: 141
Thanks: 10
Thanked 5 Times in 5 Posts



Default

I started with 120 and went up to 800 ....the surface i layed the new cf was very smooth...but i couldnt have used a different grit because the thicknes of the part at the repair spot was 0.5 mm !....so i couldnt grind the old cf to get mechanical bond...if i left it to 120 then the new cf would be some touching cf and some other touching paint or primer

Last edited by Creator; 05-31-2015 at 11:08 PM. Reason: mustake
Creator is offline   Reply With Quote
Old 06-01-2015, 12:08 AM   #4
Michiel

Composites Expert
 
Join Date: Jul 2012
Location: Netherlands
Posts: 454
Thanks: 8
Thanked 45 Times in 35 Posts



Default

You only wrapped it with one layer of 0 +45 and - 45 degrees -330gr/m2 ? That's not enough to get a good strenght.
Michiel is offline   Reply With Quote
Old 06-01-2015, 01:44 AM   #5
Creator

Member
 
Join Date: Dec 2013
Location: Limassol cyprus
Posts: 141
Thanks: 10
Thanked 5 Times in 5 Posts



Default

Quote:
Originally Posted by Michiel View Post
You only wrapped it with one layer of 0 +45 and - 45 degrees -330gr/m2 ? That's not enough to get a good strenght.
I wraped 3 lawyers of 330 gr / m2 Unidirectional carbon fiber with laminate thickness around 1.5 mm
The existing laminate that got fixed had the same layup scedule but instead if 3 layers of 330 gr the used ( i suppose) 3 layers of 100 gr / m2 of unidirectional. I examined the thickness if the existing tube and it was 0,5 mm
. I didnt have thinner prepreg so i used the 330 i i had i would go for 200.

Last edited by Creator; 06-01-2015 at 01:46 AM. Reason: Mistake
Creator is offline   Reply With Quote
Old 06-01-2015, 09:04 AM   #6
Michiel

Composites Expert
 
Join Date: Jul 2012
Location: Netherlands
Posts: 454
Thanks: 8
Thanked 45 Times in 35 Posts



Default

Quote:
Originally Posted by Creator View Post
I wraped 3 lawyers of 330 gr / m2 Unidirectional carbon fiber with laminate thickness around 1.5 mm
The existing laminate that got fixed had the same layup scedule but instead if 3 layers of 330 gr the used ( i suppose) 3 layers of 100 gr / m2 of unidirectional. I examined the thickness if the existing tube and it was 0,5 mm
. I didnt have thinner prepreg so i used the 330 i i had i would go for 200.
Ok, then ther is nothing to get worried about.
Michiel is offline   Reply With Quote
Old 06-01-2015, 11:28 AM   #7
waterlogged4

Member
 
Join Date: Dec 2012
Location: Ca
Posts: 24
Thanks: 6
Thanked 4 Times in 4 Posts



Default

I did nearly the exact same thing with an old Kestrel frame with a cracked top tube. The previous owner had filled the crack with a general 2-part epoxy after the crash and then put it on the shelf for a few years before deciding to sell it. I sanded down to the carbon before wrapping with a mix of some Textreme sample swaths and scrap 3k twill. Wet out with Pro-Set and vacuum bagged for consolidation. Sanded smooth, painted and polished. Been going strong for almost 2 years now with no issues.
waterlogged4 is offline   Reply With Quote
Reply

Bookmarks

Tags
carbon, fiber, repair

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 04:15 AM.
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

Inactive Reminders By Icora Web Design