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Composites

Week 14

PLANand MODELING


For this week I decided to make a lamp with the shape of a half sphere.



I started by drawing the 3D model of the sphere in the Rhinoceros and then cut it in the CNC machine.


In rhino I drew a ball and cut it in half. Then I attached the half-sphere to a cylinder to enlarge the size. I split the model into 3 so it fits the machine.

design and fabricate a 3D mold





In FabLab where I am we dont have a big CNC machine, we only have a small Carvey machine to machine.

And as I wanted to make a slightly large lamp I used a breathe material because it would be easier and faster in the Carvey machine.


To make the prototype of the model I decided to used as a material a XPS extruded polystyrene boards called roofmate.


The roofmate is a spongy and sturdy boards taht it's use to insulate the sound in our homes.

For this project this foam is hard enough for the shape of the mold and easy to mill in the cnc machine.






After the 3D model is done it is necessary to cut it in the milling machine.

For this, I saved the 3D model of the lamp in 3 different STL files, so that it fit in the milling machine.

Then I used the MeshCam program to define the bits for cutting the mold. And the Easel.inventables program to send information to the Carvey machine.







I cut my lampshade in the carvey machine in three parts and at the end I glued them together.



I do not advise to use this material because it makes a lot of dust and rubbish that has been put in the holes of the machine and was very difficult to clean.



I used sandpaper to get better finishes.





Before I started putting the fabric in my lampshade I studied what would be the best plan to unroll the sphere in the fabric so as not to create folds.




After that I started to plan on the fabric and on the release film and peel ply and cut it.





produce a fiber composite




Prepare the resin and make the composite

The following materials are required to produce composite fiber:

  • Release Film
  • Peel Ply
  • Release Agent
  • Fabric
  • Resin
  • Vacuum bag
  • Air compressor




  • For the process I used Entropy Resins because it is environmentally friendly.


    To make the resin, it is necessary to mix 75% of the solution with 25% Hardener


    The technical sheets can be found here:

  • Hardener Datasheet
  • Resin DataSheet


  • I started to make the material sandwich.





    The diagram at the side shows the layers I used to produce the fiber composite around my lampshade.



  • 1 - Use the separation sparay solution (wax-based)

  • 2- Put the Peel Ply and Release Film on the model

  • 3- Lay the fabric layer with a layer of resin between them. I used a brush to spread the resin better over the entire fabric, to keep the surface smooth. I made 4 layers of fabric.

    Attention: the resin solution takes about 25 minutes to dry, so the whole process has to be done quickly.

  • 4- After all the layers of fabric and resin, I returned to put the Peel Ply and Release Film to poroteger the composite.

  • 5-Put the prototype inside a bag for vacum form. I used a vacuum cleaner to pull the air, and compress all the material to the shape.

    Attention the prototype should be compressed inside the bag for about 2 days to dry well.

  • My final lamp



    After two days of waiting, here's my prototype.


    Although it has not been 100%, I am satisfied with the result.




    The shape I chose was small and round which did not facilitate the process of putting the fabric on the shape, and so the fabric got some wrinkles.


    For the next time I already know how to improve my lamp shade lamp. :)

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