How to build your own DIY Carbon Fiber/Foam Panels for ya trailer

[ebrabaek]

Impressive.

Yeppers. I was a bit surprised myself as I did not have good coverage of the thixotropic. There are so many great ways to join edges and corners and as long as you use the right bonding agent they are all good, and some stronger than others. Were I to lay down a few layers of Carbon tape on top of the joints, it would off course increase the joint even further, and quite a bit. It would also be very difficult to make it look good as our fellow member described above, but if it was needed I would off course do it. I tend to always build to purpose and need, and so far I have not come to the conclusion that it is needed. The one, and very important, point I did not test was prolonged vibration and flex. Seeing how this test flexed prior to failure, and springing back between weight changes gave me confidence in this method. Also the prior build of the front box on my then off road trailer received plenty of real trail testing as it had several heavy items bolted to the inside with no failure. Same joint and bond, but was constructed from cardboard instead of foam.

 

[ebrabaek]

Time for a bit of filler material.....Pun intended.....and make the flanges that will bolt to the truck bed.
As forementioned there are several great ways to join edges and corners. Non necessarily better than others. What matters is what works for you. Mixed a bunch of Thixotropic and then I use packaging tape along the bottom edge...... then fill the void with Thix, and tape the whole thing up. You can then either leave it, or sand it, whateveryalike....




After curing ya S...L...O...W...L...Y peal it off.....




Then I made the three flanges for the camper to sit on from 4 layers of 10 oz Plain weave 3 inch CF tape. Let it cure for a couple of hrs then placed each strip in their respectively marked positions. Camper is now upside down. Mixed more Thix....and added it to the bottom flanges....





Then with the help of my wife and youngest daughter we sat it down. You get one shot at this as the sticking power (like peanut butter) once ya set it down, it will not release. All went good and the shell is now bonded to the flanges.







You can wait a day for the strips to cure if you'd like, but you get a much better bond when the surface if the pieces are tacky so thats what I did. Tomorrow the edges will be trimmed.

 

[ebrabaek]

The edges on the bottom are now trimmed and the small void due to the angle has been filled with Thixotropic.
Now just finishing up the other edges as they cure. In the mean time I am casting the plate that will hold the main rear door/window seal. A bit of release agent..... 3 strips of the same Carbon Fiber tape at the ready.




It will off course be trimmed and will go along these edges....




Now curing.




Note the top edge which has just been filled with Thixotropic. I showed the masking tape last time as it cleans up really nice. I actually prefers to use Polyethylene tape as it flexes fantastic. Just like a plastic bag. The masking tape does not so you have to wor extra on not getting folds. The draw back from the poly is that you will have to sand the top off as the adhesive will not come off real well. Even with acetone. Well..... It will but your spending way too much time and chemicals so they will be sanded anyway.
Now curing.

 

[rruff]

I like your edge joining method and use of tape to make the filler smooth. After a bit of sanding you could even put a layer of cloth on to make it extra secure and still pretty simple and not too messy...

 

[ebrabaek]

I like your edge joining method and use of tape to make the filler smooth. After a bit of sanding you could even put a layer of cloth on to make it extra secure and still pretty simple and not too messy...

I could. Adding carbon bi-directional tape is not easy to make looking pretty.
It is a lot of work whereas unidirectional tape would be asthetically prettier and easier. Bottom line, I am certain that I have the strength I need, and then some. Truth be told if I do anything it would be unidirectional 1 inch tape and for the simple reason to protect the thixotropic from UV as a shield...... but we will see.
I use a small 1/2 x 18 inch belt sander from Harbor freight. It is so easy to hold and you can sand the edges at a constant angle with ease.

 

[rruff]

Could even use fiberglass tape. For a solid joint it's good to have a continuous "bridge" of the outer carbon layers. The radius of glue on the inner edge would achieve this, but on the outer it's really a butt-joint of the very thin skin and adhesive. Still if it works, it's good enough!

Are you not painting or coating this?

 

[ebrabaek]

Could even use fiberglass tape. For a solid joint it's good to have a continuous "bridge" of the outer carbon layers. The radius of glue on the inner edge would achieve this, but on the outer it's really a butt-joint of the very thin skin and adhesive. Still if it works, it's good enough!

Are you not painting or coating this?

No fiber glass. There are no advantages glass will offer over carbon, only disatvantages..... well perhaps exept for the cost....
Bonding diferent materials with different coeficient of thermal expansion can creat stres over time with heat cycles of the matrix. That is just one of a few reasons. It is normal to believe in a continous joint of fiber and i am not going to argue that the more continous fiber you join, the stronger it will be. But the necessity is somewhat of an old school thought. I am old school..... well at least...... i feel old.... ha ha. Many people dont fully understand the art of bonding surfaces. As such as I referred earlier in the thread there are so many methods all good. When it comes to bonding with adhesives not in a cohesive carbon is where many fall short in the trust department. Now you have to use the right stuff..... for the right purpose.
No paint..... but several coats of clear coats.

 

[ebrabaek]

The strip was trimmed in 1 inch with and two is needed to facilitate the flange for the weather strip.






Then I am dapping my hands in dangerous waters. This is perhaps not for the novice, so perhaps try this on a small piece before full scale.
If you bend composites sharply after curing it will shatter as the polymer chain has linked and set. If you let the piece dry you have a golden opportunity before full cure to carefully bend it into shape. If it shatters, your too late. If it behaves like a noodle, your early. Savvy....
One piece at the time slowly held into the corner to conform.




Now with an ample supply of tape meake sure it all fit...




Then mix thixotropic and get ready..... Bonded in place.

 

[rruff]

No fiber glass. There are no advantages glass will offer over carbon, only disatvantages..... well perhaps exept for the cost....

The fiberglass will flex much more before breaking while being nearly as strong. Coefficient of thermal expansion is about the same as carbon... and while we are on the subject I'm pretty sure the epoxy you are using has a coefficient that is multiples higher.

It will look very pretty with the clearcoats over that nice finish! Raw carbon is beautiful.

 

[ebrabaek]

The fiberglass will flex much more before breaking while being nearly as strong. Coefficient of thermal expansion is about the same as carbon... and while we are on the subject I'm pretty sure the epoxy you are using has a coefficient that is multiples higher.

It will look very pretty with the clearcoats over that nice finish! Raw carbon is beautiful.

I will disagree on the flex Glass vs Carbon, but that's ok, as this It is just my opinion, and there are plenty room for both of us.....
I dont recall the exact numbers for the CTE for both glass vs Carbon. I just remember they are different. It has been a looooong while since I did anything that had both glass and Carbon in the same matrix. I have done several layups with Carbon and K-39 (Aramid) with good results. You still have to keep that in mind though. Specially when you heat stress the layup. Last piece for me was a BMW adventure bike, bash plate so plenty of stress. Not just the heat derivative.
Raw carbon is real cool looking. Specially with a truck painted in avalanche. Something about those two combinations that I totally dig.

 

[rruff]

Fiberglass is definitely more flexible; ~3x difference in a layup. I tested that as well. In most applications that is not a good feature, but for a joint I don't see how it could hurt.

If carbon and FG are combined in a layup, the carbon will fail first due to its much greater stiffness... so you need to make sure the carbon alone is adequate for the loads. Carbon and Aramid are closer in stiffness, and with the Aramid also being weaker by about the same amount, they have better compatibility. Aramid is great for impact resistance and wear, and is quite light.

I agree about carbon being beautiful. I have some inside that is still exposed and it is very 3-D looking with a shiny topcoat. What are you planning to use for a clearcoat? Whatever I use can't be very stinky, because it's inside and I can't wait too long for the fumes to subside.

 

[ebrabaek]

Fiberglass is definitely more flexible; ~3x difference in a layup. I tested that as well. In most applications that is not a good feature, but for a joint I don't see how it could hurt.

Once you begin mixing composites with different torsional stiffness the box, in this case, will not flex evenly. One of the benefits to Thixotropic (THIX) is that it actually stays somewhat flexible as a joint and still hold on to what ever you bond with it. In the aerospace industry it is commonly used to bond spars to ribs and in some cases skin to ribs. It ensures a great bond between the two halves or parts.

Glass in a joint properly wont hurt, but it be ugly and I'm not a fan working with it due to the fact that it is...ehhh... uhmmm.... glass.... The bigger picture, however, and as aforementioned is that it is not needed structurally in this construction. Regardless if it is glass or carbon it is extra work and difficult to make it look pretty. I am past the days where I lay up stuff and sand it smooth, unless off course the project dictates me doing so.

I will be using a high quality automotive clearcoat (2 part) that I will spray on outside. I plan on 4 layers. None a total wet in to stay in the satin finish.

 

[ebrabaek]

There is nothing like breaking a mold, uncovering a bond job or other ways unmask a layup the next day. It is just so rewarding. It is also important to realize this on a big build like this where it certainly is easy to get lost in a row boat on the ocean. These small steps, achievements is what will pull you through.
Unmasked.......





A bit of rounding off the edge and then time for a test of the main door seal.....








The two bottom flanges will be trimmed off about 1/2 inch in fitting the door but that will be done on the truck to ensure a perfect fit.
This then paves way to begin the construction of the main door.





Masking tape is again used for clear markings. Then the outline of the uncompressed gasket is traced.....





Then enlarged by 10mm outwards, and marked. Ready for trimming.





Trimmed, and checked. All is quiet on the western front. Carry on.

 

[ebrabaek]

Und zeeeeen vie getz to make ze koooorners und edgez..... Jaaa.....
Traced the outline of the main door, and trimmed 4 edge flange mathingies. Taped the 4 strips in place and added ....... wait for it......... Waaaaait...... THIXOTROPIC......





Then you get one shot at plumping down the main piece. That THIX is one of the most stickies things I have ever seen. Been stuck in mud, but this is incredible really. Have a helper if you can.





Add whatever THIX you have left over and use a popsicle stick to smooth the radius. Now curing.

 

[ITTOG]

I like how you make yourself laugh!

Good work! Do you have a link to where to buy the thixotropic online? I would like to read more about the stuff. Also, is it just for carbon fiber or is it for FG as well?