Re: DIY Carbon fiber repair - seatstay.
Posted: Tue May 16, 2017 5:59 pm
I didn't take pics of my test-pipe, before I started in with destructive testing.
At first, I thought... there is not enough resin in here. Did I squeeze out too much? I was all set to try again, but decided to run some tests on it.
I can't crush it with Channel-lock pliers, or break it, holding on with pliers.
It is VERY difficult to score with a razor knife.
With all my might (I'm a cyclist, that is not a lot of might), I can't break this by hand.
In wrestling with it, the only damage I could do was to snap the pipe, where it meets the repair.
I finally stuck a steel rod in each end of my little carbon fiber "pipe". Laid the works over a 2x4 board, and stood on the ends of the pipes. It finally broke at the point where I joined the pipe together. I'm confident that a pristine seat-stay would have failed the same test. So... instead of more testing... I'm just "going for it" on the bike. Worst case, I need to sand it back and try again.
The seatstay, with a layer of epoxy. I stressed the stay a bit, to get the epoxy to flow in as best I could. I'll let this set up for the next 10 minutes while I cut my sheet.
BTW, I mixed the epoxy by weight and not volume. I learned later, that isn't ideal. It seems to work just fine, so far.
Here's my sheet of plain-weave. I honestly didn't put a ton of thought into the length/number of wraps. My logic went like this.... my test was plenty strong. My seatstay is thinner than my test-pipe. I'll just cut a length of fabric longer than I used for my test. I'll have more wraps than my test... it will be strong. I forgot to count the wraps, so I don't even know how many there are. If anyone wants, I can figure it out, since I put a ruler in the picture.
Ready to tape. Make sure the tape is wrapping in the direction of the fabric wrap. This is a place where doing a test was very valuable in doing a good job. I found that wrapping the fabric tightly is difficult, because the epoxy is slippery. getting the first wrap tight sucks. It wasn't tight on my test.
On this, I wrapped all the wraps as best I could, then just kept tighting the roll over the stay. I probably turned it in place 5 times before it really snugged up. Once snug, I didn't much care where the fabric ended on the outer wrap.
Sorry for the focus. it happens a lot in this project. This is the tape, wrapped tightly, epoxy oozing out as I go, but locked-in once wrapped.
This is really out of focus. it's a shame, because you can really see the value in the pin-hole method of this technique.
At first, I thought... there is not enough resin in here. Did I squeeze out too much? I was all set to try again, but decided to run some tests on it.
I can't crush it with Channel-lock pliers, or break it, holding on with pliers.
It is VERY difficult to score with a razor knife.
With all my might (I'm a cyclist, that is not a lot of might), I can't break this by hand.
In wrestling with it, the only damage I could do was to snap the pipe, where it meets the repair.
I finally stuck a steel rod in each end of my little carbon fiber "pipe". Laid the works over a 2x4 board, and stood on the ends of the pipes. It finally broke at the point where I joined the pipe together. I'm confident that a pristine seat-stay would have failed the same test. So... instead of more testing... I'm just "going for it" on the bike. Worst case, I need to sand it back and try again.
The seatstay, with a layer of epoxy. I stressed the stay a bit, to get the epoxy to flow in as best I could. I'll let this set up for the next 10 minutes while I cut my sheet.
BTW, I mixed the epoxy by weight and not volume. I learned later, that isn't ideal. It seems to work just fine, so far.
Here's my sheet of plain-weave. I honestly didn't put a ton of thought into the length/number of wraps. My logic went like this.... my test was plenty strong. My seatstay is thinner than my test-pipe. I'll just cut a length of fabric longer than I used for my test. I'll have more wraps than my test... it will be strong. I forgot to count the wraps, so I don't even know how many there are. If anyone wants, I can figure it out, since I put a ruler in the picture.
Ready to tape. Make sure the tape is wrapping in the direction of the fabric wrap. This is a place where doing a test was very valuable in doing a good job. I found that wrapping the fabric tightly is difficult, because the epoxy is slippery. getting the first wrap tight sucks. It wasn't tight on my test.
On this, I wrapped all the wraps as best I could, then just kept tighting the roll over the stay. I probably turned it in place 5 times before it really snugged up. Once snug, I didn't much care where the fabric ended on the outer wrap.
Sorry for the focus. it happens a lot in this project. This is the tape, wrapped tightly, epoxy oozing out as I go, but locked-in once wrapped.
This is really out of focus. it's a shame, because you can really see the value in the pin-hole method of this technique.