Wild card (composite)

A composite is made by combining two or more other materials so they improve one another but keep distinct and separate identities in the final product. Composite are usually made of at least 2 components, a fiber and a matrix material which roughen the fiber.

For this week I ll create a shinguard composite for my leg. I used sense first generation 3d scanner to scan my leg and then used Rhino to create the cast. It was extremely tough to deal with the stl file recieved from the 3d scanner as it contained huge number of polygons. As the purpose for this shin-guard is for my personal use thus 3d scanning was the only precise option for that purpose. Please check my 3d scanning and printing week for more information on 3D scanning

Fiber and resin

To create the composite I decided to use the Jute fiber and one Epoxy resin (general purpose laminated resin). the epoxy is a clear, general use, epoxy laminating resin for composites, coatings, and adhesive applications. It took me around 15 hours to fully cure my composite. Despite their natural derivation, exposure to these materials represents hazards typical to all epoxy resins.Exposure should be minimized and avoided through the use of proper protective clothing and equipment and appropriate manufacturing controls. I have noticed that the material could get extremly hot once it start curing with the jute. other than that the smell of the hardner material do really stinks.

Design

Murad-leg by murad_ron9 on Sketchfab

1- Decrease the number of polygon to 15000 2- Draw a triangle and used it to split (Mesh split command)the 3d mesh 3- Transform the shape to to 2d (make2d command) 4- place the 2d on the mesh 5- Extrude the 2d shape 6- Use split to create the first cast 10- Export the 2 file in an stl format

source Files:

download 3d scanner stl file

download rhino file

download rhino stl file for the positive cast

download rhino stl file for the negative cast

Getting the cast ready

I have checked my design and both of my cast are about 80 mm thick, 400 mm * 180 mm dimension. So with the help of Sibu, we cut the plywood to small pieces and stack them on each other and glued them to be ready for the cut.

Cutting the cast ( shopbot v-carve)

I ll be using the shop-bot to cut my cast, as my part is actually very big. Using v-carve to cut a 3d model object, is pretty similar to cutting a 2d object, however for the 3d object, make sure you select the modeling tab instead of the drawing tab and choose 3d roughing tool. Always make sure that your tool would be able to get down without bumping into wood ( we replaced our milling bit to 1/2 inch straight cut).

Creating the composite

  1. I placed food wrap on my cast, I heated it using the heat gun to perfectly attach.

  2. I added the holed wrap (ask sibu for the name) above the food wrap

  3. Mixed the resin 100 g of One epoxy to 50 g of ONF hardener (ratio 2 to 1)

  4. Placed the jute on top of the casting

  5. Slowly placed the resin on top of the jute and made sure it spreads everywhere.

  6. Add the hole rap (ask sibu about the name )

  7. Finally placed food wrap on it to not stick to the vacuum bag

  8. placed the mold in the vacuum bag and used the vacuum cleaner.

Final results

The composite is was cured in about 18 hours, I took it off and cut it according to the size of the shin-gaurd that I wanted.

Notes:

  • I only used one layer of jute, as I don’t need much thickness to ease my movement on the field while wearing it.

  • I have found out that the wrap with hole have actually sticked to the Composite and gave it a very nice finish from both sides,

  • I could try placing my silicon mold (from molding and casting week) and then create the composite it would give a better feel when I place it on my leg