Carbon project

lennymc

I got a frame that had some cracks in it, it was a write-off, but, looking at some of the repairs that were done I decided that I would give fixing it a go. I used to fix motorbike bodywork with fibreglass, so have done a little bit of repairs. Ill try to keep a log here of how I get on. Should be an interesting project. If its successfull ill use it on the turbo trainer. I

Stage 1. Some of the chainstay sections were destroyed, so I cut them out with a hacksaw. One of the seat stays was cracked, but I was able to sand that out.

I'm looking at epoxy and carbon suppliers, anyone have any recomendations?

lizzylad84

Lenny, these photos made me cry.....make it better....

macnab

I repaired a Boardman carbon frame last year with great results. I bought a starter kit from www.carbonmods.co.uk. It cost about €60 but I have most of it left over even though I wrapped the crossbar 5 times. I didn't cut out the damaged section though, instead I sanded it down until it was wafer thin. That way I could use it as a former for the new carbon fibre. Take your time with it and you will see great results. I tapered in to the crack and put on wider and wider layers. Each layer is wet on both sides and compressed with a sheet of plastic which is treated with a release agent on the inside and wrapped heavily with plastic tape on the outside to compress the bandage. Look it up on YouTube and you will find some very informative videos.

moonshadow

Lenny, have a chat with FergalB, a mod on the boat forum....he is a genius with this type of stuff and knows all the contacts.

FirstinLastout

http://www.aorsurfboards.com/blog/

This guys has repaired a few MTB's far as I know.

granda

would it not be safer and easier to get a bit of alu or something machined/ bent into shpe as a plug to join both ends and then wrap it in carbonfiber/fiberglass especially if its just going to be used on the turbo

detones

Interesting article here on the subject of cf repairs.

http://m.bicycling.com/maintenance/repair-maintenance/resurrection-calfees-carbon-frame-repair

Will be looking on with interest as to how you get on Lenny.

Harrybelafonte

This is going to be interesting. My skills along these lines are limited, but info can always plug that gap and eBay has had a few very, very cheap damaged race bikes I've been tempted by lately.

lennymc

macnab wrote: »

I repaired a Boardman carbon frame last year with great results. I bought a starter kit from www.carbonmods.co.uk. It cost about €60 but I have most of it left over even though I wrapped the crossbar 5 times. I didn't cut out the damaged section though, instead I sanded it down until it was wafer thin. That way I could use it as a former for the new carbon fibre. Take your time with it and you will see great results. I tapered in to the crack and put on wider and wider layers. Each layer is wet on both sides and compressed with a sheet of plastic which is treated with a release agent on the inside and wrapped heavily with plastic tape on the outside to compress the bandage. Look it up on YouTube and you will find some very informative videos.

Thanks for the comments! Surprisingly, no "are you c razy, your going to die" comments yet....

macnab - Ironically, i think I sold you that cracked frame.....

Ive been looking at some of the kits alright. I'm not sure if they will do for what I want tho. I think I want some UD cf to build into an insert with 4 layers in different orientations, that will bridge the gap where I cut out the sections, and then wrap it with another 4 layers in differeing orientations. Ill then build it back into the stay after step sanding it. Im not concerned about matching the cf weave, but would hope to try to get it at least matching the original profile. I did think about sanding the cracked segments, but, the cracks went all the way round, so I still would have ended up with a gap in the chainstays.

I will keep this thread updated, but they will be sproadic rather than regular updates. There is so much information out there - fibreglast.com have a really good learning centre.

doozerie

I think this is a great idea and I wish you luck with it. I'm a big fan of tackling any task myself so I can really see the appeal. At the very least it'll be a very interesting learning experience, I expect you could learn a lot about frame design while doing this in addition to learning a lot about the properties of carbon. That alone would be well worth the time and effort, in my opinion.

lennymc

doozerie wrote: »

I think this is a great idea and I wish you luck with it. I'm a big fan of tackling any task myself so I can really see the appeal. At the very least it'll be a very interesting learning experience, I expect you could learn a lot about frame design while doing this in addition to learning a lot about the properties of carbon. That alone would be well worth the time and effort, in my opinion.

That's what Im thinking. I was very surprised to see how thin the carbon tubing walling is when I cut through the stays. I must measure it actually, and post up a picture. My fix, should (in theory) be very over engineered because I will be doubling or so the thickness of the CF where the cracks where, and bonding it to both the inside and outside of the chainstay. My theory could be very much off tho, and it could collapse!!

Anyway, if it works great. If not, at least I will have the experience.

I would love to build my own frame at some stage. A lovely steel fillet brazed track bike - something like this should do it:



once I am finished with this carbon frame I think I will build a lugged steel frame or two, before trying the fillet brazing. Sure its a few years down the road yet. I wonder does the btw scheme cover tubing.....

Donie75

West System epoxy is good stuff. It's used in the marine sector. SP Resins are good too.
You should also look into Vacuum Bagging. That's how all the high end yacht racing stuff is made. It uses a vacuum to remove all the air pockets from the lay up. You should be able to find info about DIY vacuum bagging online.

One other thing... take out health insurance with a dental plan...

lennymc

Donie75 wrote: »

One other thing... take out health insurance with a dental plan...

sure ye could say that about any cycling

I have heard of west system epoxy,. and have looked into vacuum bagging. I was looking at how to create a seal around the chainstay, as I dont think it would be possible/feasible to bag the entire frame?

CardinalJ

I remember when I was in school trying to help a guy fix set of carbon magic wheels he'd cracked going into a car park with them on the roof. Was a doomed project from the off and we ended up with itchy arms for days from the carbon

Hope this goes substantially better!! Good luck.

cdaly_

lennymc wrote: »

looked into vacuum bagging. I was looking at how to create a seal around the chainstay, as I dont think it would be possible/feasible to bag the entire frame?

If you can create a tube of bag around the stay, then it's just a matter of blu-tack and cable ties at each end to make a reasonable seal. A hot-wire bag sealer from Lidl should be able to make the tube of bag...