# Anyone DIY a carbon frame



## GiantTrek (Jan 12, 2014)

I have some experience building canoes, kayaks, and rowing shells with fiberglass and Kevlar. 

I was wondering if anyone has experience with building their own carbon fiber bikes. It seems totally doable, but was hoping their might be some experienced folks on here to share their stories.


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## Walt (Jan 23, 2004)

Lots of people have done it and many have documented it. Start googling or pester Drew!

-Walt


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## Testmule (Jul 27, 2013)

*CF frame*

Yup, have done it.

You are peering over the edge of the rabbit hole Alice, so it's only fair to warn you that you will probably have more into equipment and materials than if you just went out and bought one. In addition, manufactured CF frames have lots of engineering designed into making them strong, light, and really pretty.

Some of the things you need will include a vacuum pump that will pull down 26 inches of mercury, a fixture to assemble the frame, and a hot wire cutter, ect. ect.

These things considered, you can make your own design, and have some fun doing it. Walt is also correct; Drew is the premier member on this board working with CF.


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## GiantTrek (Jan 12, 2014)

Your bike looks fantastic. 

Did you make those patterns or did you buy them somewhere? 

Or if this has all been hashed out in an existing thread - could someone point me to it?

I enjoy projects like this, and it could be a fun father/son, father/daughter project.

Gracias


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## Drew Diller (Jan 4, 2010)

Testmule said:


> Drew is the premier member on this board working with CF.


LMAO, fools!

I've been working on tools for months and my workshop for three months, producing nary an end object, so I read this and went: ¿que?

If that's how I'm seen around here, that is very flattering and I am trying to make good on it.

OP I am pretty confident Testmule made those patterns. I am not a big vac bag fanatic but they are a necessity.

I do enjoy the core/filler shaping part of things. Quiets the mind, like wood carving.

Look up some work by Mr.Magura.

I prefer to steer away from room temperature epoxies like West System, it's really hard to get a lot of material down all in one go with a 20 to 30 minute pot life, _especially_ if you are working alone. I like epoxies that cure between 100 and 200 F, but that raises the question of: are you willing to bring heating elements into the mix? If not, then room temp is the way and multiple cure cycles to build up enough material might be necessary.

No question is stupid on the topic of composites, I still have a lot to learn too.


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## Testmule (Jul 27, 2013)

GiantTrek

Drew is correct that I made the patterns and cores for the tubes. Bristol board to make the patterns and then lay them on the pink insulation foam (available at building centres) and cut them out with a hot wire cutter (find on ebay). Using a metal yard stick as a guide help keep them straight. I sanded the shapes with 80 grit - I think, but be careful you can remove a lot of material in a hurry. The pink insulation is the right density and sands into a grainy dust.

To make the measurements for frame tubes just find a frame you like the size and geometry for and use those specs. Make the tube cores longer than you need by a few inches and then cut the excess when you join the tubes.

I had some initial problems vacuum bagging the slender stay cores in that when pump pulled down the vacuum the tension wanted to twist the fragile core material and I found that wrapping with a single thin layer of CF and left to harden on its own helped with this. In some cases I used wood braces on top of the bagging material to clamp the cores in position. You can see this in one of the above pics.

I know I'm making this sound easy, but I have 40 years of fabrication experience in a lot of materials, but that said, building a CF frame isn't beyond a home project. You will just have to research and experiment.

You can search this forum for more info on CF.


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## unissamog (Jun 10, 2006)

I built one last winter w/o vacuum, using room temperature cure epoxy. I borrowed a frame jig, but was able to build a hardtail carbon frame for around $400 total. I am starting my 2nd frame this month, a full suspension enduro frame. There is a ton of websites and videos out there discussing building carbon bikes, Google and youtube will yield a large amount of information.


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## 2silent (Dec 19, 2008)

Ask yourself why? Is your goal to build a bike that doesn't exist that you want? To learn more about fabrication (if so- to what end?).

Here is my latest major project. I try hard to do as little work as possible to create what I want.


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## GiantTrek (Jan 12, 2014)

2silent said:


> Ask yourself why? Is your goal to build a bike that doesn't exist that you want? To learn more about fabrication (if so- to what end?).
> 
> Here is my latest major project. I try hard to do as little work as possible to create what I want.


I am a glutton for punishment. And a little of both. Enjoy making things, like boats, and have always wanted to make a bike. The fat bike craze has made me want to try one even more.

It's a great bike for a failure because the speed is usually slow and the rides are almost all in snow or on the beach.

Great bikes folks!!


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## Roadsters (Jul 7, 2008)

Watch this. It's neat.


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## campergf23 (Aug 4, 2013)

I want to try this, and I have a friend with a vacuum pump!


Sent from my iPhone using Tapatalk


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## GiantTrek (Jan 12, 2014)

How did you folks decide on which weight/weave to use. 

How many layers in different locations? 

What did you do for bottom brackets and steering tube? 

What type epoxy did you use?

Thanks


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## Testmule (Jul 27, 2013)

GiantTrek said:


> How did you folks decide on which weight/weave to use.
> 
> How many layers in different locations?
> 
> ...


Whoa! Lots of questions - some easy, some not.

Steering tube - no taper 6061T6 aluminum, pre-machined for 1 1/8, and a 4130 BB shell - both wrapped in a single layer of fiberglass and resin to isolate them from the carbon fiber, and subsequent galvanic corrosion.

There are lots of resins you can use, but epoxy resin is required with CF to achieve maximum strength. I choose one that specified ultra-violet filters because I didn't paint the frame to give protection from deterioration in sunlight. West Systems is the best known epoxy resin - at least in North America.

Unidirectional carbon fiber cloth is the strongest in one direction, but almost none at 90 degrees. This is where experimentation and engineering are called for to achieve a light weight frame that is also strong, and frame manufacturers have invested plenty into this.
In my understanding manufacturers only use bidirectional cloth for the final wrap to give the sexy look, which I did on the last one I built.

Carbon strands come in different modulus ratings; high meaning much more money and tougher availability. This is where you will need to research and educate yourself. I have a book by Deborah Chung titled Composite Materials: Engineering Materials and Processes, in ebook format that I would recommend.

Thickness wise - well, one thing to remember is that carbon fiber only achieves light weight and strength when the optimum resin content is reach. This is where the vacuum process squeezes the resin down to roughly the thickness of the cloth. Most of the tubes I formed I was looking for .035 to .060 " finished product. Wrapping the joints is not near as accurate, and the last fat bike frame I built I ended up around 3.6 lbs. - heavy for a carbon frame, but no issues at all other than a little flex under hard peddling around the BB area.


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## Drew Diller (Jan 4, 2010)

GiantTrek said:


> How many layers in different locations?


I can't add much to what Testmule responded with, other than this is a somewhat loaded question, but more specifically, another term for you to search is _areal weight_.

Some cloths are thicker or thinner per square area and therefore heavier/stronger. To alleviate some confusion, gsm and g/m2 are the same thing, grams per square meter. There are some handy conversion tools for dealing with imperial units, it seems like many distributors like to use different terms.

As a simple example, you could make a nearly functionally identical tube out of 12 layers @ 150 g/m2, or 6 layers @ 300 g/m2. Make sense?

The main reasoning for various densities that I've worked has to do with thicker fabrics are harder to form out of complex shapes, thinner fabrics are easier. Complexity of shape vs efficiency in laying down as few plies as possible to save time, and the compromise therein. I'm using 300 g/m2 prepreg unidirectional (I wish the term was monodirectional) on my current project, and it is very hard to form into small, complex shapes... which makes sense because it's usually used for making windmill blades and large industrial stuff.


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## Testmule (Jul 27, 2013)

One more small detail I forgot to add from my novice learning of the carbon fiber science. Bidirectional weave (the pretty stuff) actually loses strength each time the strands are woven under and over each other. This is why the unidirectional is the strongest; at least in one direction. The woven cloth loses strength each time it is bent over and under.

The rabbit hole is indeed deep...


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## compositepro (Jun 21, 2007)

Not so much on a DIY basis but I've worked with it for a while back 20 years ago nearly we did it on a DIAY basis as we had to do everything ourselves there was no one to ask no books and no forums


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## jmatz (Mar 10, 2014)

If you're open to taking a class rather than going it alone and having to buy all the tools, etc., I think Dave Bohm was planning on having a class on carbon building. But not sure if he's to that point yet. His steel building class is wonderful.
Bohemian Framebuilding school


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## back40 (Apr 15, 2006)

I've built about 10 carbon frames over the last few years. Tube to tube construction only. Most of the build process I've documented here...

back40 bicycleworks

So far just road and cross frames, no mtb yet.


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## Drew Diller (Jan 4, 2010)

back40 said:


> I've built about 10 carbon frames over the last few years. Tube to tube construction only. Most of the build process I've documented here...
> 
> back40 bicycleworks
> 
> So far just road and cross frames, no mtb yet.


You're doing nice stuff there. Keep it up.

I'm curious about your oven. Home brew?


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## Flip D (Sep 16, 2005)

back40 said:


> I've built about 10 carbon frames over the last few years. Tube to tube construction only. Most of the build process I've documented here...
> 
> back40 bicycleworks
> 
> So far just road and cross frames, no mtb yet.


That is a very informative blog. Best source of info I've seen since the Crumpton thread over on Velocipede and I could probably ask you about 1,000 questions. Thanks for sharing.


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## GiantTrek (Jan 12, 2014)

Thanks for the replies. Decided it's a go. Now to start getting some materials, and know how.

I've used the West system a fair amount. Have some left over supplies from boat builds. 

Any suggestions on fiber suppliers? Also the BB and steer tube? Any precut / tapped suppliers to recommend?


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## GiantTrek (Jan 12, 2014)

Back40

Your blog is great. 

Makes me wanna start building. Also seems like it could be addicting and before long you could have a whole personal marina or bike fleet.


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## back40 (Apr 15, 2006)

Drew Diller said:


> You're doing nice stuff there. Keep it up.
> 
> I'm curious about your oven. Home brew?


It's home made. A simple sheet metal box with fiberglass then foil backed rigid foam. It uses two oven elements and a $100 PID temperature controller. There is a heat diffuser plate and a fan to stir the air and even out the temp.

Building it again I'd add a small window and a air/vacuum port through the wall as well as a better fan.


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## back40 (Apr 15, 2006)

GiantTrek said:


> Back40
> 
> Your blog is great.
> 
> Makes me wanna start building. Also seems like it could be addicting and before long you could have a whole personal marina or bike fleet.


I'm looking into making shaped tubing in female molds with internal inflating bladders next which will of course lead to a new frame or two. Once you start it's hard to stop making them better.


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## back40 (Apr 15, 2006)

back40 said:


> I'm looking into making shaped tubing in female molds with internal inflating bladders next which will of course lead to a new frame or two. Once you start it's hard to stop making them better.


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## Drew Diller (Jan 4, 2010)

Thanks for the feedback on your oven, back40. If you have any troubles making inflation bladders, I've had some encouraging and fun times with making silicone rubber hollow forms using a rotocasting machine.

Other people have succeeded using two polyethylene sheet and welding a pattern into the plastic using a soldering pen, with a sheet of parchment paper between PE sheet and soldering pen. I have been decidedly _not_ successful with that route, most of mine burst too willingly, but give it a shot because it is so cheap. Just because I couldn't get the PE approach to work... doesn't mean you cannot get it to work.



back40 said:


> Once you start it's hard to stop making them better.


HA! Yeah.

Yeah....


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## GiantTrek (Jan 12, 2014)

Still have the questions about the bottom bracket and the head tube. 

Did you tap your own or did you buy them pre cut and threaded? Seams like it would be hard and require special tooling to tap threads that large and to be sure they are absolutely aligned on both ends?


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## Drew Diller (Jan 4, 2010)

GiantTrek said:


> Still have the questions about the bottom bracket and the head tube.
> 
> Did you tap your own or did you buy them pre cut and threaded? Seams like it would be hard and require special tooling to tap threads that large and to be sure they are absolutely aligned on both ends?


Right!

Buy a BB shell, it's worth the money. If aluminum, prevent galvanic corrosion with an insulator layer etc.

Head tube is much easier to consider build vs buy questions. If buying, Rockwest is one idea, this could potentially be two head tubes for $50 - 45202-01 - Rock West Composites

If you want some 49.57mm ID head tubes, send me a PM, I have some from that I ordered from Carbon Fiber Tubing - it would be an economical option, but you're going to lose some savings because of the headsets currently available in that size.


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## GiantTrek (Jan 12, 2014)

So the weight weenie in me is curious what your bikes weighed in at?


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## Testmule (Jul 27, 2013)

GiantTrek said:


> So the weight weenie in me is curious what your bikes weighed in at?


Around 3.8 lbs. Heavy for a carbon frame, but I wanted it a little beefy. No issues at all with one fall and winter season on it already.

You can buy BB shells already tapped in a range of sizes from Paragon Machine.


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## GiantTrek (Jan 12, 2014)

http://www.westsystem.com/ss/assets/HowTo-Publications/Vacuum-Bagging-Techniques.pdf

The journey starts... Found a great resource on vacuum bagging.


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## GiantTrek (Jan 12, 2014)

Any one have any advice on vacuum pumps. Brands they like, CFM recommendations? Hg requirements?


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## GiantTrek (Jan 12, 2014)

So I made my first part - sort of. Just a test piece. First time vacuum bagging, and can't believe I never used this method on glassing wooden boats??? 

It was un-nervingly simple. Much easier than working with wood, and clamps. Used a simple, recycled refrigeration pump, for vacuum. Bought this from a local repair shop for $10. Test piece was done with left over glass and resin. 

Now to buy some carbon fiber and make some real parts.


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## GiantTrek (Jan 12, 2014)

First piece was a 16" x 1" tube using foam as a core. Weight about 1oz. Weighed a section of steel tubing the same size = 1 lb.


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## Bogrider (Mar 31, 2014)

Testmule said:


> Yup, have done it.
> 
> You are peering over the edge of the rabbit hole Alice, so it's only fair to warn you that you will probably have more into equipment and materials than if you just went out and bought one. In addition, manufactured CF frames have lots of engineering designed into making them strong, light, and really pretty.
> 
> ...


Hey testmule. I'm looking at building a carbon frame and am wondering how to get the bottom bracket held up in a jig similar to yours. What's the part in yours in the last pic that's holding the bottom bracket in place?


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## Testmule (Jul 27, 2013)

Bogrider said:


> Hey testmule. I'm looking at building a carbon frame and am wondering how to get the bottom bracket held up in a jig similar to yours. What's the part in yours in the last pic that's holding the bottom bracket in place?


2" round aluminum stock turned into cones in a lathe, then bored or drilled for 1/2" rod.
A friend of mine turned them for me. I haven't found an easier way to do it, but there may alternatives as long as they hold the BB shell square.


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## Bogrider (Mar 31, 2014)

Testmule said:


> 2" round aluminum stock turned into cones in a lathe, then bored or drilled for 1/2" rod.
> A friend of mine turned them for me. I haven't found an easier way to do it, but there may alternatives as long as they hold the BB shell square.


Awesome! Thanks a lot for the quick response. Hopefully I can get going here soon.


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## Bogrider (Mar 31, 2014)

So probably something that's been answered before but how do you know how much higher the center of the rear dropouts should be over the center of the bb?

Or if there is a thread for this please let me know. Sorry.


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## PCSailor (May 6, 2014)

jeez, I'm envious. And I wish I had the time!!


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