Carbon fiber drama

[sbell111]

I am trying to figure out how to cast carbon fiber blanks, but am having tons of trouble.

First, these carbon fiber 'tubes' unravel if you look at them too hard. Next, it is surprisingly difficult to get them onto the tubes perfectly straight. Finally, the fiber appears to outgas as the PR sets up.

Does anyone have any words of advice to help me with my problems?

 

[broitblat]

Steve,

I cut the tubes longer than needed and use extra long corks (corks attached to dowels) and tape both end to the dowels to stretch and keep relatively straight and avoid unraveling.

Still, I had a fairly high failure rate so the last batch I just bought from Gary/CaptG.

-Barry

 

[LEAP]

I haven't done carbon fiber but on my rope pens I put some thin CA on the ends to bind the fibers together. Like Barry I make them longer than they need to be then cut to length after casting.

 

[jleiwig]

I am trying to figure out how to cast carbon fiber blanks, but am having tons of trouble.

First, these carbon fiber 'tubes' unravel if you look at them too hard. Next, it is surprisingly difficult to get them onto the tubes perfectly straight. Finally, the fiber appears to outgas as the PR sets up.

Does anyone have any words of advice to help me with my problems?

If you think that is difficult you should try a full sized car hood! The only thing that sounds weird to me is the outgassing. Is the carbon preimpregnated?

 

[sbell111]

If you think that is difficult you should try a full sized car hood! The only thing that sounds weird to me is the outgassing. Is the carbon preimpregnated?

Huh?

 

[ldb2000]

What you think is out gassing might be the PR pulling away from the tube due to shrinkage . For clear casts you would be better off using Alumilite , it don't shrink as badly as PR .

 

[workinforwood]

I think Gary's blanks are PR. I don't see him speaking up..might be his little trade secret. Can't say I'd blame him if it is!

 

[CaptG]

My trade secret is my fixture for getting the carbon fiber on straight and not bunched up. Steve, I powder coat the tubes before I glue the cf on. I really believe the PR (I use silmar 41) reacts with a lot of the paints and will soften up under the cf. If you use cork to plug the tubes, it will have porus spots and will let the pressure build up inside the tube. When you degas the pot, the pressure from inside the tube will work back out thru the cork, but when it gets to the hardened pr, it will look for the path of least resistance, the softened up paint, and wick into that spot and bleed thru the cf giving you the dreaded silver shimmer. I use silicone plugs and it helped a lot, but did not stop the problem completely until I started the powder coat process. I also use the pr to glue the cf to the tube, then let it cure at least 48 hours before casting. This is how I cast my carbon fiber and the above are my observations from a long and rocky road to get where I am with my casting. Hope this helps.

 

[penmanship]

I am trying to figure out how to cast carbon fiber blanks, but am having tons of trouble.

First, these carbon fiber 'tubes' unravel if you look at them too hard. Next, it is surprisingly difficult to get them onto the tubes perfectly straight. Finally, the fiber appears to outgas as the PR sets up.

Does anyone have any words of advice to help me with my problems?

The easiest solution to this problem (I found) is get ahold of Gary (CaptG......:biggrin This way "my" blanks are consistent & perfect EVERY time!

 

[jleiwig]

Huh?

Carbon fiber by itself will not in anyway outgass unless it is pre-impregnated with resin. Of course if your using this, likely your also using an autoclave to cure the prepreg in as well (think Indycar). :wink:

What I would look at doing is making a fixture that would hold your carbon tube and have a tenon to hold the brass tube. Then you could just slide the carbon off the fixture and onto the brass tube. I should be getting some carbon hybrid tubes in different colors in the next couple weeks. I'll try and take a picture of what I'm describing.

 

[sbell111]

My trade secret is my fixture for getting the carbon fiber on straight and not bunched up. Steve, I powder coat the tubes before I glue the cf on. I really believe the PR (I use silmar 41) reacts with a lot of the paints and will soften up under the cf. If you use cork to plug the tubes, it will have porus spots and will let the pressure build up inside the tube. When you degas the pot, the pressure from inside the tube will work back out thru the cork, but when it gets to the hardened pr, it will look for the path of least resistance, the softened up paint, and wick into that spot and bleed thru the cf giving you the dreaded silver shimmer. I use silicone plugs and it helped a lot, but did not stop the problem completely until I started the powder coat process. I also use the pr to glue the cf to the tube, then let it cure at least 48 hours before casting. This is how I cast my carbon fiber and the above are my observations from a long and rocky road to get where I am with my casting. Hope this helps.

Thanks. That's a big help.

I'm revamping my process with Charlie's resin saver molds so this looks like as good time to completely review each detail. I hadn't thought of using teh PR as glue. That's an awesome idea.

Carbon fiber by itself will not in anyway outgass unless it is pre-impregnated with resin. Of course if your using this, likely your also using an autoclave to cure the prepreg in as well (think Indycar). :wink:

What I would look at doing is making a fixture that would hold your carbon tube and have a tenon to hold the brass tube. Then you could just slide the carbon off the fixture and onto the brass tube. I should be getting some carbon hybrid tubes in different colors in the next couple weeks. I'll try and take a picture of what I'm describing.

Clearly 'outgas' was a poor term to use. I have no doubt that Gary nailed my issue. Hopefully, Charlie's molds will solve that problem for me.

 

[jleiwig]

Thanks. That's a big help.

I'm revamping my process with Charlie's resin saver molds so this looks like as good time to completely review each detail. I hadn't thought of using teh PR as glue. That's an awesome idea.

Clearly 'outgas' was a poor term to use. I have no doubt that Gary nailed my issue. Hopefully, Charlie's molds will solve that problem for me.

Gary has given you good description of what he does. Charlie's molds will only help with the casting part, not the getting the cloth on the tube with out it twisting or unraveling. Carbon is a real bitch to work with at times. You may also want to look at the died s glass that looks like carbon fiber. It usually holds together better, is cheaper, and easier on the body.