(another) Carbon Frame Repair question- Mtbr.com
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  1. #1
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    (another) Carbon Frame Repair question

    I've got a frame thats taken a bit of damage in transit. I suspect it's had something dropped on it, there's paint missing and a long thin area (maybe 5mm by 60mm) that is compressible. The frame owes me nothing, so I'm tempted to have a go at repairing it.

    Has anyone any advice, or point me in the direction where i can find some?

    I'll scrape some paint of it to start with, and see the full extent.

    (another) Carbon Frame Repair question-img_1413.jpg(another) Carbon Frame Repair question-img_1414.jpg

  2. #2
    will rant for food
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    Have a chat with Drew Wilson / Cyclocarbon, his responses are usually fast.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  3. #3
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    Thanks Drew, but id feel a bit cheeky asking a company that repairs frames professionally to tell me how to fix my own!

  4. #4
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    Plastic | Peter Verdone Designs

    Not a step by step level of detail for beginners but should be enough info in the for you to figure it out. I kinda forget if PVD might have an older post on another repair.

  5. #5
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    I'm unsure as to how much material to remove, before starting repair. I've started sanding it down, the more i sand, the deeper i chase the delaminations. At this rate i will keep going until i've just got a hole. The damaged area is 10mm wide, 70mm long. I'll post a few pictures.

  6. #6
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    I'd just strip the paint off the top tube and see what you're working with. Use cheap knife and scrape the paint off by drawing the knife perpendicular to the surface. It should be an easy repair. No need to remove material. Do a full wrap of the area and compress it. Here's an overview of my last repair.

    https://forums.mtbr.com/yeti/diy-fra...r-1124339.html

  7. #7
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    Iíve scraped the paint off, I think that was the only structural item left! The carbon is just strands. I can see into the tube.

  8. #8
    EAT MORE GRIME
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    whatever you do don't press or squeeze on it to check for flex and damage limits, that just creates more cracks and delam. tap/rap on it and listen but do not squeeze. it's fixable
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  9. #9
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    (another) Carbon Frame Repair question-img_1416.jpg(another) Carbon Frame Repair question-img_1417.jpg(another) Carbon Frame Repair question-img_1418.jpg

  10. #10
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    I don't need to squeeze, its just a hole with a frayed mess around it. I can see into the tube.

    I think a strip 20mm wide and 80mm long fails the tap test, within that there is basically a hole 10mm wide 60mm long. So how much "bad" material do i grind away to prepare for a patch? All the way until i hit good carbon again?

  11. #11
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    I think removing and replacing the "bad carbon" isn't the best approach. You'll want to create a new tube with a new layup over the damaged area. the damaged spot should be filled with epoxy putty. this will provide a solid structure for the new layup to compress against. the new layup should extend as far as possible over a solid tube for it to bond against.

  12. #12
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    I get you, but the middle part is so damaged that there isn't anything to rebuild into a solid structure. Hard to see in the photo's, but it's basically just a hole. Certainly not rigid enough to compress against.

    I know nothing of carbon, so this might be stupid. Can i fill part of the tube with expanding foam or similar and then use this as something rigid to compress my new laminations against?

  13. #13
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    The epoxy putty is surprisingly good at filling the gaps. It also hard to see in the photos, but the last repair I did had about 2" of completely delamanated carbon. The tubes were nearly severed off.
    (another) Carbon Frame Repair question-1301197d1575732967-diy-frame-repair-20191130_085629-1-.jpg
    (another) Carbon Frame Repair question-008aa100280d507b89f360a294c7d478.jpg

  14. #14
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    I'd seen that, nice repair job!

    I'll have a think and come up with a plan to add some rigidity to what i have now. How many layers should i be adding to my repair?

    Theres lots of carbon repair kits for sale on the internet. Anything i specifically should be aware of?

  15. #15
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    for the price of a kit ($90 shipped) I got enough material for 20 of these repairs from

    https://compositeenvisions.com/


    I used 3 layers of 2x2 2k weave. medium cure hardener, thin epoxy, and Hishrink tape.

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