Fixing a cracked carbon fiber seat base?

[fist]

Originally Posted by puresyn

Auto Parts store should have it. The fiber/fibre looks like a cloth weave. Sometimes you can get those there also. Not sure what brands they have in Australia, but the Bondo brand is famous here in the US. It comes in a kit with a hardener.

Bondo is an auto body filler. it dries as hard as cement, i doubt he would want something like that on his seat

[puresyn]

Originally Posted by fist

Bondo is an auto body filler. it dries as hard as cement, i doubt he would want something like that on his seat

http://www.bondo-online.com/catalog_browse.asp

They don't just make filler anymore, although that is what they are best known for.

[skilewis74]

Originally Posted by petri

AFAIK you need to bake carbon fibers in an oven. That makes it impractical for DIY. Glass fiber is easy to use in a garage environment in comparison.

Didn't somebody enforce his CF base with a metal plate (as a precaution). I think I remember reading that in some other thread. That's too late now but for your next seat.

Yeah, you need an oven. I met a guy who mad some cf go-cakt fairings w/ a metal box and a heat lamp. I think I heard it was possible to make cf w/o heating it, it would end up stronger than fiberglass, but not nearly as strong or light as cf.

Muzzle cracked his and I think he made an aluminum stiffener plate for it. When he could afford a new cf base he said he was going to put his plate on that for a super strong base.

[puresyn]

Originally Posted by skilewis74

Yeah, you need an oven. I met a guy who mad some cf go-cakt fairings w/ a metal box and a heat lamp. I think I heard it was possible to make cf w/o heating it, it would end up stronger than fiberglass, but not nearly as strong or light as cf.

The oven is for high tech CF. Its is usually used with high-tech $100 per gallon resins, e.g.; if you are making an item that needs to resist temperatures over 150F degrees--then yes you need an oven. It's extremely unlikely that Luke will need an oven to repair a seat since he is not going to use the $100 epoxy and complex kevlar fibers. He is just repairing a seat, not designing the next generation of armor. And no, a heat lamp does not qualify as high tech cf anymore than your freezer constitutes as a cryogen chamber.

These complex CF are mainly used for things like motorcycle mufflers that need temperatures of over 150F. Thats why they are so godly expensive.

[skrobo]

from what i know about carbon fiber you work it the same as fiberglass, the oven method is for special stuff. YOu want to get epoxy resin, you should be able to find some for a reasonably low price. i don't know about using the small tubes of epoxy you can find at wal-mart... but it is much better than polyester or vinyl resin. i think the sandwich method will work, but i'm going to suggest putting 2 layers on top, one strip with the crack and a few going acrosss it to support it.

[brendan]

you probably be better off buying a kit like this
http://www.carbonology.com/shop_det....14&sec_id=2116

basically you need to stick carbon fibre matting on either side of the seat base and stick it down with resin. Now you can get into endless debates about epoxy vs polyester. Epoxy is probabaly better but harder to use.

But if you see the price of the kit a new base is 10 quid more... so is it really worth it?

Also you could do without the carbon fibre and use 2 layers of fiberglass to get it back together. This would be cheaper and could be easier. Maybe try talking to auto body repair people in your area or talk to anyone that works in composites. THats what i did for my tech project and i made a carbon fibre desk and the university near me gave me all the materials !

As for oven baking thats for very high strength resins and while it'd be nice to use you dont wnat to put precured CF with uncured CF in the same oven.

[muzzle]

Originally Posted by skilewis74

Muzzle cracked his and I think he made an aluminum stiffener plate for it. When he could afford a new cf base he said he was going to put his plate on that for a super strong base.

Nah, wasn't me. I have been riding with modified classic saddles (drilled to fit KH handles) and am on my thrid one of those since I broke my CF base in half. Will be buying another CF base soon (before unicon denmark), although I'm not looking forward to snapping another one!

[UniDudeDX]

Pics???

[muzzle]

Originally Posted by UniDudeDX

Pics???

Here's a gallery of the 1st classic saddle I made with KH handle:
http://www.unicyclist.com/index.php?..._itemId=324056
http://www.unicyclist.com/index.php?..._itemId=324070

Is that what you wanted pics of?

[elastoplastscavenger]

Originally Posted by petri

AFAIK you need to bake carbon fibers in an oven. That makes it impractical for DIY. Glass fiber is easy to use in a garage environment in comparison.

not true. only certain types of carbon fiber construction require that (and its called an autoclave, not an oven )

id suggest running some very well mixed epoxy resin into the cracks. best use 2 or 3+hour set time stuff than can be bought from most DIY/hardware/hobby/radio controlled shops. You will probably find carbon fiber cloth there too, especially in shops that do radio controlled planes. patch the cracked area with the cloth and resin (while the first lot is still wet) if the cloth had fibers running in all directions then one or two layers will be fine. If the fibers all run in one direction then put several layers with the fibers running in several directions.

Once that is done you might even want to carefully and gently (not too hot) warm the area with a hair dryer or similar to make the epoxy resin go runny and run nicely into all the cracks. Dont expect the end product to be as strong as the original!