Re-bonding frames....

[Xesh]

I've decided that it's time for me to look at re-furbishing my Litage carbon frame. I've done a search on google for the carbon frame but I only get information on the alu frame. Are these frames really that rare?

While I can easily sort the corrosion on the lugs, the BB/down tube joint needs re-bonding. Is it something I can do myself, or will I have to send it away? I have no problem with making a jig to hold the frame for re-bonding but what adhesive do I need and how do I de-bond the necessary joints without damaging them? The other question I've got is whether the bonding process can be done at room temperature or does it need an oven curing process?

Time isn't an issue for this, as I have a usable bike at the mo, so I can take as long as necessary for this.

 

[Gruff]

Try asking danson67 he may be able to help.

 

[We_are_Stevo]

Some adhesives achieve glass-like state at surprisingly low temperatures - you could easily debond the joints with a heat-gun. Some adhesives are curable by air-drying, others you could do with the same heat-gun. A risk of de-laminating the carbon fibre though.

Loads of specialist suppliers on the Web who could advise - marine applications would be ideal...

 

[lumos2000]

google structural bonder 1152, though you may find somthing more sutible for carbon. ive used this stuff in room temp for boat building and it withstands vibration.
ask a boat building supplyer for info as there loads of diffrent types for diffrent aplications

 

[lumos2000]

plexus is another
http://www.itwplexus.co.uk/index.php?/p ... -products/

 

[mooster]

Try also these guys, they carry out repairs to carbon fibre parts and are recognised in the TT world as the place to go if carbon repairs are needed!

http://www.fibre-lyte.co.uk/

 

[danson67]

Thanks for the plug, Gruff....

I've had some success in unbonding carbon/alu, but usually with external lugs. Pace RC31 forks for example can be shortened by removing the dropouts, trimming the tubes and rebonding. (Down to 20" for a BMX mini racer ) With internal lugs, the different expansion rates of carbon and alu are working against you.

You might be able to spring the frame enough out and sideways to access the lug and tube without messing with any of the good joints. Get a feel for the springiness of the frame. Otherwise, as the Down tube/BB joint has come apart, aim to debond only the top tube/head tube joint. The frame can then be split in two parts (DT/HT and TT/ST/Stays) which will slip back together in one shot, leaving the original HT/DT joint well alone if posssible.

I used an even gentle heat (Air gun) to around 80 degC, don't use a really high setting as the heat will delaminate the carbon. The carbon will be able to resist delaminating up to at least it's original cure temperature, probably around 150 degC. Problem is that the bonding epoxy could still be pretty strong up to 150deg at least. So there could be a bit of a crossover, you'll need to pull and twist... Hopefully the original designer used a bonding epoxy with a lower service temp than the CF composite epoxy...otherwise it just won't come apart without 'burning' the carbon tube.

Columbus and Deddacciai both recommend Araldite 2014 for their carbon stays. Room temperature bonded. A heated bond only quickens the process, 8 hours at 23 deg will be fine. Instruction sheet at http://www.intertronics.co.uk/data/ara2014-1.pdf
Basically; sand, degrease and rebond...

Check all the joints are back in tight and the HT and ST are parallel. 2014 has an open time of around 60 minutes, so there's no hurry.

All the best,

 

[Xesh]

Thanks for the info. I'll give it a try and let you know how I get on. Maybe I'll take a few pics too.