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Carbon Repair

manhattanprjkt83

Rusty Trombone
Jul 10, 2003
9,647
1,219
Nilbog
I could have searched but that would have been way too easy. I have an evil wreckoning I got from a buddy which has a very minor gouge to the carbon (3mm or so) in the middle of the seat stay. Honestly it doesn't look like its even fully through the carbon. I am planning to repair it and use it as my dh bruiser for next season. What have you folks used for carbon repair in the past? I checked w/ a couple of these online places, one guy was a complete asshole about the color I wanted it painted and the other was a bit pricey (1k). I think I can probably do the repair and home respray for around $250, will be a good winter project.

Input?
 

Jm_

sled dog's bollocks
Jan 14, 2002
19,267
9,907
AK
Sheet of 1m or yard about $40, West system epoxy and hardener. Few mixing cups, some paper tarps and PPE.
 

Westy

the teste
Nov 22, 2002
54,832
20,692
Sleazattle
Plenty of good youtube videos on this subject but my $.02. Since you don't know what the layup of the damaged carbon is use a woven fabric and rotate 45 degrees between layers. Sand the damaged part to remove everything broken and create a smooth transition. Taper your repair so you just don't cause a stress riser at the edge of it. I'd put the smaller layers of fabric on first then go bigger beyond that. I'd recommend trying to get your hands on shrink release tape to make sure you have good saturation, no bubbles and not too much epoxy.



Even better if you can get your hands on some peel ply but a good poor man's method is to just use electrical tape with the adhesive side out.

Since you will have 10X the materials you need for this repair practice a bunch on a wooden dowel or something similar in shape to the tube you want to repair.

Mix two batches of expoxy, wet out the fabric on some wax paper and let it tack up a bit before you apply, small bits of fabric like to come unwoven unless something holds it together a bit. Use a fresher batch of epoxy to further wet out when you apply it to the frame.
 
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manhattanprjkt83

Rusty Trombone
Jul 10, 2003
9,647
1,219
Nilbog
Plenty of good youtube videos on this subject but my $.02. Since you don't know what the layup of the damaged carbon is use a woven fabric and rotate 45 degrees between layers. Sand the damaged part to remove everything broken and create a smooth transition. Taper your repair so you just don't cause a stress riser at the edge of it. I'd put the smaller layers of fabric on first then go bigger beyond that. I'd recommend trying to get your hands on shrink release tape to make sure you have good saturation, no bubbles and not too much epoxy.



Even better if you can get your hands on some peel ply but a good poor man's method is to just use electrical tape with the adhesive side out.

Since you will have 10X the materials you need for this repair practice a bunch on a wooden dowel or something similar in shape to the tube you want to repair.

Mix two batches of expoxy, wet out the fabric on some wax paper and let it tack up a bit before you apply, small bits of fabric like to come unwoven unless something holds it together a bit. Use a fresher batch of epoxy to further wet out when you apply it to the frame.

I really appreciate this man, that's why I love RM to this day. Thanks for putting so much detail behind this. I'll post pics of my progress.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,805
4,775
Champery, Switzerland
What @Westy said and pay attention to the tapered layers he suggests.

https://www.easycomposites.co.uk/carbon-fibre-rapid-repair-kit

https://www.easycomposites.co.uk/fishing-pole-repair-kit

I‘ve had good experiences with their epoxies, breather cloth and peel ply. Their epoxy is much nicer to work with than something like the West Systems 102 and it’s much stronger. Sicomin is my favorite these days. When doing snowboard layups the quality of the epoxy makes everything nicer. The Greenpoxy 56 works just like a normal epoxy fyi.

http://sicomin.com/
 

rideit

Bob the Builder
Aug 24, 2004
23,595
11,724
In the cleavage of the Tetons
Hey guys, before I send this pic off to Calfee, do you have any thoughts on this? Seems like it would be a substantial repair. (Friend's bike). She was on a bike-pack trip, kind of had to death-march it through gumbo for miles and miles.
Sounds like expensive type-2 'fun'!
1000004053.jpg
 
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Jm_

sled dog's bollocks
Jan 14, 2002
19,267
9,907
AK
Hey guys, before I send this pic off to Calfee, do you have any thoughts on this? Seems like it would be a substantial repair. (Friend's bike). She was on a bike bike-pack trip, kind of had to death-march it through gumbo for miles and miles.
Sounds like expensive type-2 'fun'!
View attachment 199848
That would be challenging to fix IME. The easiest to fix is a tube where the break or damage is halfway down the tube. The further displaced from that, the harder. Like after you get it all sanded down and everything, wrapping CF around it vertically isn't really going to do much to fix it, you need to distribute the load, which is in tension, which basically is going to take longer strips running more horizontally IMO. It's also going to be a royal bitch to sand down in front of that enough.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,805
4,775
Champery, Switzerland
@rideit I think that looks like an easy fix. You could mix up a paste of chopped carbon strands in epoxy to fill the hole and then let cure before doing your layup. A kit like this one would have everything you need.


My last carbon project grafting a Ransom seat tube onto a Gambler front triangle.

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