Carbon Fiber mold 6

[dipstick]

Tube Construction:
I'm in the process of making a 2.5 inch tube with a gradual 90 degree bend on both ends for the purpose of creating a custom cold air intake for a Miata MX5. This cold air intake has to serve a dual task. One is to reach downward to the air dam and bring in cold air upward to a resevoir blasting across a high flow air filter. This filter takes the cool air to the injection system via the 2.5 inch tube previously described. My problem is that being new to using fiber, I'm accustomed to metal and intended to use aluminum but fiber caught my attention, what should I use for mold material and how can I get the two 90 degree bends and all of this being one piece? Anybody!
Great admirations to those minds in the sky,
Dipstick

 

[kognition]

Anthony,
It does take a little getting your mind around it, but if you are new to composites... i suggest getting to know the materials first so you get a handle on it. Making tubes is indeed a task for those with experience. I for one do not post images of our manufacturing processes (and most companies do not. But i have explained above how you can do it. And there are a few different ways to do it. I would check google again
this time adding the domain extension "EDU" for the Universities which do post video and images of course projects.
Mike

 

[kognition]

As an afterthought,
If you are new to composites, it really has nothing to do with mold making. Both are completely different realms. But wanting to learn one, will force you to learn the other eventually. But once you get the basics down for both, you are really only limited by your imagination and budget.

 

[makaveli200369]

I just ordered some books on it. I am trying to volunteer at a co-workers friends shop where he builds aircraft parts. I'll sweep the floors to learn and see how it all works.

 

[scapaldo]

http://www.turbomustangs.com/techarticles/PBcarbonfiber.php

This should give you a basic idea of the process, you just need top apply it to making a pipe.

Kog, have you had any problems with the seams between the 2 mold halves. I havent started yet but I would think it would be difficult to get it seamless. Thanks

 

[kognition]

Yes you do get expulsion in between the seems. However, if your mold rubber is at least 1" in thickness all around, you wont get any weird things happenning to your shape (assuming you are working under a vacuum bag). The seam acts as a vent for excess epoxy. And aids in removing any hidden air pockets if you are using the wet layup method. The resulting seam edge is easily blended away with some 1,000 grit wet/dry paper.

 

[makaveli200369]

scapa thanks for that link..that is the best link I have seen yet! Thanks for posting it.

 

[kognition]

We do use vacuum pumps from mini fridges. You can buy a new mini fridge for about $60. We make alot of small cf parts and have 10 mold tables with dedicated mini vacuum pumps mounted underneath each wood table. These tables are on wheels as well. If you need more info on constructing your own vacuum pump, you can check this site:

http://www.dream-models.com/eco/vacuumpump.html#N100A7

 

[scalliwag]

Hi Kognition, what is the name or link for the company that makes sailboat steering wheels. I am trying to figure out how to make a steering wheel out of carbon fibre.

 

[kognition]

http://www.exitengineering.com/

Basically they expand cf within a mold by use of a bladder like an inner tube. But the bladder i think remains in the part permanently so they must be making low cost bladders out of plastic or something.

 

[alex1212]

What will not stick to the carbon fiber and epoxy? I want to make a mold out of foam you can buy at a craft store. Will I end up with the epoxy sticking to this?

 

[kognition]

No you do not want foam coming in contact with your epoxy or carbon/glass etc. Your mold should be smooth so your part comes out smooth. And you should consider making your mold with modelling clay and or quick setting cement like "cement all". But there are variables i don't know about your project which would give a better idea of what materials to use to make your mold. RTV silicone rubber is an excellent material that you can pour over your part (providing it is a fairly simple shape). The RTV i use sets up quick and just needs to set overnite before use. RTV usually does not require a mold release, but if the part is under vacuum, there is a tendency for small particles of the mold to lift off of the surface. So
a mold release is suggested. Then you just strip the mold release from the cured part with mineral spirits.

 

[MikeHalloran]

For simple molds of appropriate shape, Saran wrap can work as a mold release.



Mike Halloran
Pembroke Pines, FL, USA

 

[kognition]

Yes, saran wrap is excellent and we use it everyday actually. But Mike is right, it depends on what your shape is. It does not do well in compound curves using CF because the saran has a tendency to crease in curves and this creates actual creases in the finished surface of CF that really cannot be fixed unless you sand in out (bad idea btw).

 

[alex1212]

Thanks guys..all im doing is making a small intake for a motorcyle. very easy shape with out any complex bends. saran wrap sounds like it will work for a first try.

 

[MikeHalloran]

Another option for small frp parts is to make a negative of the part from paraffin, by directly sculpting a cavity, and filling it with resin and fiber.

Paraffin also makes an excellent core for parts like intake tracts. You can wrap wet fiber on it to make a tube directly. It gets more difficult if the tube needs ears at the ends.



Mike Halloran
Pembroke Pines, FL, USA