Other Resources > Maintenance, Mechanics, & Tools

Carbon-repair process of my TFSA (SL6 clone) frame

(1/3) > >>

TidyDinosaur:
So I crashed my 1 month old TFSA frame 2 weeks ago. In the process I hit a metal pole with the horizontal part of the non drive chainstay... This caused my frame to crack in this spot. I also cracked my collarbone, but that's healing nicely after some surgery...

I asked for a quote for the repair and the cheapest I got was 250 € without paint (I asked for this since I can just cover it up with some black plastic protection foil)...
Since the frame is about 450€, I decided to just get another frame instead of having it repaired...

I like DIY and I like working on bikes so I have also decided to try the repair myself and keep the bike for the smart trainer. I am not confident enough in my carbon repair knowledge (=none) to ride the bike outside after the repair.

So this is what it looked after the crash:


So I ordered all the supplies to do the repair myself and watched a lot of youtube... The supplies were 130€ but I got too much of everything (including 1m² of 200g/m² 3k carbon sheet) and it included some stuff I will not need to use so that could be a lot lower...

This afternoon I went for the first step: sanding it down. I used a Dremel and just some 150 grit sanding paper for sanding by hand.

During sanding it became obvious that the cracks are rather big so just sanding away some patches here and there was not going to work. I decided to sand the whole area where the cracks were so it would be easier to cut and apply the new carbon patches.

If the weather is OK I will apply the new carbon patches and epoxy tomorrow. I was thinking to start with a big square patch that covers almost the entire sanded area, than a second patch that is about 1cm smaller and than end with 1 big square to cover the 2 previous and hopefully leave a nice finish... I have shrink tape to wrap the spot afterwards and hopefully squeeze out the excess epoxy.

This is where I stand now:

Wet Noodle:
I've heard that the textbook way was to make the sanding area smaller and smaller (towards the crack) as you go deeper into the laminate. Each layer should be exposed ~2 cm wide or something like that. Then just build up laminate the opposite way, starting with smaller pieces and getting larger by each layer (think tetris). Ideally, you'd want something like a "layered scarf joint" between the old and the new laminate (I hope that makes sense).

Just something I picked up from people who seemed actually knowledgeable on the topic (as opposed to me). I have no background in composites and might have got it wrong.

TidyDinosaur:

--- Quote from: Wet Noodle on July 29, 2023, 11:28:22 AM ---I've heard that the textbook way was to make the sanding area smaller and smaller (towards the crack) as you go deeper into the laminate. Each layer should be exposed ~2 cm wide or something like that. Then just build up laminate the opposite way, starting with smaller pieces and getting larger by each layer (think tetris). Ideally, you'd want something like a "layered scarf joint" between the old and the new laminate (I hope that makes sense).

Just something I picked up from people who seemed actually knowledgeable on the topic. I have no background in composites and might have got it wrong.

--- End quote ---

And you can also find experts that say you have to start with the largest piece of carbon and build up with smaller and smaller pieces...

The problem is that there are multiple cracks in the location I'm working on. And they also run in different directions... That's why I decided to just sand away a lot... In some area's there is almost no carbon left...
I'm just going to use this frame inside so it's not that critical...

TidyDinosaur:
This morning I continued the process. I had cut 3 patches yesterday but they were not big enough when I tried them on the tube so I had to redo it... I decided to not use 3 separate patches because it would be difficult with the seams since I would have to wrap each patch around the tube. I went for one long piece or carbon that tapers from one end to the other and that I can wrap around the tube 3 times.



I started with the smallest end and wrapped it around the tube. Afterwards I wrapped it with shrink tape to compress everything. Now it will have to harden until tomorrow... I don't think it will win any beauty prices, but it looks nice and sturdy after a few hours of hardening...

Sebastian:
Are you using pre preg sheets or dry cloth and apply the resin+hardener afterwards?

Navigation

[0] Message Index

[#] Next page