Carbon fiber backplate

[AKinnunen]

CF Backplate
Here is perhaps the most difficult system to make a backplate. I’ve made several backplates using aluminum and stainless steel now I want something new. I have some previous experience making composite parts, which is why I decided to make a carbon fiber backplate.

Design
I used my old design, just because I like it. I moved some grooves and hole positions because they were too near the outer edge for CF


Mold and Lamination
I designed the mold so that I could 3D print it. Because this was my first 3D printed mold, I made some mistakes with material selection and surface coating, but the final result is almost okay. After painting the molds, final grinding, and waxing mold was ready for lamination.

I prepared all materials ready because the epoxy I use has a handling time of just 30 minutes. For lamination, I used two layers of 240 g/m² for both surfaces; this gives a nice outlook, and inside I have 6 layers of 400 g/m² carbon fiber. This combination gives around 3.2 mm thickness.


Finishing
After grinding all the edges, I started to make holes using a milling machine. I designed and printed simple jigs to make the work easier. I also added some titanium grommets to every screw hole.

I planned to make a shiny surface, but for some unknown reason (not due to epoxy mixing), the thin surface coating layer did not dry well. I spent hours removing it, and the result isn’t very nice. For the next version, I will use a different resin.

Now I understand the process, tools, and materials, and I know how to do it next time. The next version will be perfect.



Br: Arto

 

[Sascha314]

Whats the weight and buyoncy of it? Nice project.

 

[AKinnunen]

Hi,

The weight is around 450g, and the same plate in aluminum is around 650g. The density of CF laminate is around 1.7-2g/cm³, while aluminum has a density of 2.7 g/cm³. In practice, the only benefits are a cool appearance and good corrosion resistance.

Br: Arto

 

[Badger7]

Nice work! That is quite impressive! If I had access to the materials and machinery, I would be doing the same. Instead of shopping for specific features on a plate, you can design yours any way you want! I notice you don't have any cam band slots milled in. Do you dive double tanks or are you going to make yourself a nice carbon fiber single tank adapter?

 

[AKinnunen]

I made it only for my SF2 CCR, but it's a good idea to make a super light single-tank traveling version.

 

[Badger7]

I made it only for my SF2 CCR, but it's a good idea to make a super light single-tank traveling version.

Agreed. Cam band slots, molded in tank stabilizer, and no deep channel since you wouldnt need to clear any fasteners. That would be pretty cool. Heck, might as well take a plaster cast of your back and use that for the layup mold!

 

[profmason]

Nice compression molding. I would recommend a much slower epoxy to get a better finish. Also avoid polyester resins as they are hydrophilic. Reach out to Jerry at Polymer composites for a specific recommendation, but I use their max bond($30 on ebay) in ROV applications. I like to use a CO2 laser cutter to precut the carbon fiber cloth with all the features to save the mill post processing step. Put the positive features in your mold to help with alignment.

Also more old school would be to do a clay mold and vacuum bag over it, but have also switched to 3D printed compression molds for ease. Per Badger above, 3D scan back and print a mold.

 

[AKinnunen]

I once made a backplate that was based on the 'arc of the back.' It also worked very well. I used it for a few years; it was actually very comfortable


Br: Arto